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Search for "phase-transfer catalysis" in Full Text gives 26 result(s) in Beilstein Journal of Organic Chemistry.
Active-metal template clipping synthesis of novel [2]rotaxanes
- Cătălin C. Anghel,
- Teodor A. Cucuiet,
- Niculina D. Hădade and
- Ion Grosu
Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130
- -functonalized stopper 3 after substitution of bromine with azide. The dialkyne-decorated pyridine 5 was prepared starting from 2,6-bis(bromomethyl)pyridine that was reacted with compound 4, under phase transfer catalysis (Scheme 1). Finally, the axle 6, as well as the reference macrocycles M1 and M2 [44], were
Graphical Abstract
Figure 1: a. Active-metal template (reported in the literature) and b. active-metal template clipping (used i...
Figure 2: Macrocyclic components of the [2]rotaxanes.
Scheme 1: Synthesis of the key intermediates 6 and 8 and of the reference macrocycle M1.
Scheme 2: Synthesis of [2]rotaxanes R1 and R2.
Figure 3: Top: HRESI(+)-MS spectrum of the rotaxane R1 (left) and R2 (right) [experimental (top) and calculat...
Synthesis of ether lipids: natural compounds and analogues
- Marco Antônio G. B. Gomes,
- Alicia Bauduin,
- Chloé Le Roux,
- Romain Fouinneteau,
- Wilfried Berthe,
- Mathieu Berchel,
- Hélène Couthon and
- Paul-Alain Jaffrès
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
Graphical Abstract
Figure 1: Chemical structure of some natural ether lipids (ELs).
Figure 2: Synthesis of lyso-PAF and PAF from 1-O-alkylglycerol [64].
Figure 3: Synthesis of lyso-PAF from 1,3-benzylideneglycerol 3.1 [69].
Figure 4: A) Synthesis of the two enantiomers of octadecylglycerol (4.6 and 4.10) from ᴅ-mannitol (4.1); B) s...
Figure 5: Four-step synthesis of PAF 5.6 from (S)-glycidol [73].
Figure 6: Synthesis of 1-O-alkylglycerol A) from solketal, B) from ᴅ- or ʟ-tartaric acid and the intermediate ...
Figure 7: Synthesis of EL building blocks starting from substituted glycidol 7.1a–c [82].
Figure 8: Synthesis of PAF 8.5 by using phosphoramidite 8.2 [86].
Figure 9: Synthesis of oleyl-PAF 9.7 from ʟ-serine [88].
Figure 10: Synthesis of racemic analogues of lyso-PAF 10.8 and PAF 10.9 featuring a phenyl group between the g...
Figure 11: Synthesis of racemic deoxy-lyso-PAF 11.7 and deoxy-PAF 11.8 [91].
Figure 12: Synthesis of racemic thio-PAF 12.8 [93].
Figure 13: Racemic synthesis of 13.6 to illustrate the modification of the glycerol backbone by adding a methy...
Figure 14: Racemic synthesis of 14.5 as an illustration of the introduction of methyl substituents on the glyc...
Figure 15: Synthesis of functionalized sn-2-acyl chains of PC-EL; A) Steglich esterification or acylation reac...
Figure 16: Synthesis of racemic mc-PAF (16.3), a carbamate analogue of PAF [102].
Figure 17: A) Synthesis of (R)-17.2 and (S)-17.6 starting from (S)-solketal (17.1); B) synthesis of N3-PAF (17...
Figure 18: Modification of the phosphocholine polar head to produce PAF analogues [81].
Figure 19: Racemic PAF analogues 19.3 and 19.5 characterized by the absence of the phosphate group [107].
Figure 20: Synthesis of PIP3-PAF (20.7) [108].
Figure 21: Large-scale synthesis of C18-edelfosine (21.8) [116].
Figure 22: Synthesis of C16-edelfosine (22.10) starting from isopropylidene-ʟ-glyceric acid methyl ester (22.1...
Figure 23: Phosphocholine moiety installation by the use of chlorophosphite 23.2 as key reagent [119].
Figure 24: Synthesis of rac-1-alkyl-2-O-methylglycerol (AMG) [120].
Figure 25: Synthesis of stereocontrolled 1-alkyl-2-O-methyl glycerol 25.9 (AMG) from dimethyl ᴅ-tartrate [81].
Figure 26: A) Racemic synthesis of thioether 26.4 [129,130], B) structure of sulfone analogue 26.5 [129].
Figure 27: Stereocontrolled synthesis of C18-edelfosine thioether analogue 27.8 [118].
Figure 28: Synthesis of thioether 28.4 that include a thiophosphate function [134].
Figure 29: Synthesis of ammonium thioether 29.4 and 29.6 [135].
Figure 30: Synthesis of the N-methylamino analogue of edelfosine 30.6 (BN52211) [138].
Figure 31: Synthesis of 1-desoxy analogues of edelfosine; A) with a saturated alkyl chain; B) synthesis of the...
Figure 32: Stereocontrolled synthesis of edelfosine analogue (S)-32.8 featuring a C18:1 lipid chain [142].
Figure 33: Synthesis of edelfosine analogues with modulation of the lipid chain; A) illustration with the synt...
Figure 34: Synthesis of phospholipid featuring a carbamate function to link the lipid chain to the glycerol un...
Figure 35: Synthesis of sesquiterpene conjugates of phospho glycero ether lipids [148].
Figure 36: Racemic synthesis of methyl-substituted glycerol analogues 36.7 and 36.10: A) synthesis of diether ...
Figure 37: Racemic synthesis of ilmofosine (37.6) [155,156].
Figure 38: A) Stereoselective synthesis of 38.5 via a stereoselective hydroboration reaction; B) synthesis of ...
Figure 39: Racemic synthesis of SRI62-834 (39.6) featuring a spiro-tetrahydrofurane heterocycle in position 2 ...
Figure 40: Racemic synthesis of edelfosine analogue 40.5 featuring an imidazole moiety in sn-2 position [160].
Figure 41: Racemic synthesis of fluorine-functionalized EL: A) Synthesis of 41.6 and B) synthesis of 41.8 [161-163].
Figure 42: A) Synthesis of the β-keto-ester 42.6 that also features a decyl linker between the phosphate and t...
Figure 43: Synthesis of phosphonate-based ether lipids; A) edelfosine phosphonate analogue 43.7 and B) thioeth...
Figure 44: Enantioselective synthesis of phosphonates 44.3 and 44.4 [171].
Figure 45: Racemic synthesis of phosphinate-based ether lipid 45.10 [172].
Figure 46: Racemic synthesis of edelfosine arsonium analogue 46.5 [173].
Figure 47: Synthesis of edelfosine dimethylammonium analogue 47.2 [118].
Figure 48: Synthesis of rac-C18-edelfosine methylammonium analogue 48.4 [176].
Figure 49: A) Synthesis of edelfosine N-methylpyrrolidinium analogue 49.2 or N-methylmorpholinium analogue 49.3...
Figure 50: A) Synthesis of edelfosine’s analogue 50.4 with a PE polar group; B) illustration of a pyridinium d...
Figure 51: A) Synthesis of 51.4 featuring a thiazolium cationic moiety; B) synthesis of thiazolium-based EL 51...
Figure 52: Synthesis of cationic ether lipids 52.3, 52.4 and 52.6 [135,183].
Figure 53: Synthesis of cationic carbamate ether lipid 53.5 [184].
Figure 54: Synthesis of cationic sulfonamide 54.5 [185].
Figure 55: Chemical structure of ONO-6240 (55.1) and SRI-63-119 (55.2).
Figure 56: Synthesis of non-ionic ether lipids 56.2–56.9 [188].
Figure 57: Synthesis of ether lipid conjugated to foscarnet 57.6 [189].
Figure 58: A) Synthesis of ether lipid conjugated to arabinofuranosylcytosine; B) synthesis of AZT conjugated ...
Figure 59: Synthesis of quercetin conjugate to edelfosine [191].
Figure 60: Synthesis of 60.8 (Glc-PAF) [194].
Figure 61: A) Synthesis of amino ether lipid 61.7 functionalized with a rhamnose unit and its amide analogue 6...
Figure 62: A) Synthesis of glucose ether lipid 62.4; B) structure of ether lipid 62.5 possessing a maltose uni...
Figure 63: A) Synthesis of glucuronic methyl ester 63.8; B) structure of cellobiose 63.9 and maltose 63.10 ana...
Figure 64: A) Synthesis of maltosyl glycerolipid 64.7; B) structure of lactose analogue 64.8 prepared followin...
Figure 65: A) Asymmetric synthesis of the aglycone moiety starting from allyl 4-methoxyphenyl ether; B) glycos...
Figure 66: A) Synthesis of ohmline possessing a lactose moiety. B) Structure of other glyco glycero lipids pre...
Figure 67: A) Synthesis of lactose-glycerol ether lipid 67.5; B) analogues possessing a maltose (67.6) or meli...
Figure 68: Synthesis of digalactosyl EL 68.6, A) by using trityl, benzyl and acetyl protecting groups, B) by u...
Figure 69: A) Synthesis of α-ohmline; B) structure of disaccharide ether lipids prepared by using similar meth...
Figure 70: Synthesis of lactose ether lipid 70.3 and its analogue 70.6 featuring a carbamate function as linke...
Figure 71: Synthesis of rhamnopyranoside diether 71.4 [196].
Figure 72: Synthesis of 1-O-hexadecyl-2-O-methyl-3-S-(α-ᴅ-1'-thioglucopyranosyl)-sn-glycerol (72.5) [225].
Figure 73: A) Preparation of lipid intermediate 73.4; B) synthesis of 2-desoxy-C-glycoside 73.10 [226].
Figure 74: Synthesis of galactose-pyridinium salt 74.3 [228].
Figure 75: Synthesis of myo-inositol derivative Ino-C2-PAF (75.10) [230].
Figure 76: A) Synthesis of myo-inositol phosphate building block 76.7; B) synthesis of myo-inositolphosphate d...
Figure 77: A) Synthesis of phosphatidyl-3-desoxy-inositol 77.4; B) synthesis of phosphono-3-desoxyinositol 77.9...
Figure 78: A) Structure of diether phosphatidyl-myo-inositol-3,4-diphosphate 78.1; B) synthesis of phosphatidy...
Figure 79: A) Synthesis of diether-phosphatidyl derivative 79.4 featuring a hydroxymethyl group in place of a ...
Figure 80: Synthesis of Glc-amine-PAF [78].
Figure 81: Synthesis of glucosamine ether lipid 81.4 and its analogues functionalized in position 3 of the ami...
Figure 82: Synthesis of fully deprotected aminoglucoside ether lipid 82.5 [246].
Figure 83: Synthesis of C-aminoglycoside 83.12 using Ramberg–Bäcklund rearrangement as a key step [250].
Figure 84: A) List of the most important glyco lipids and amino glyco lipids included in the study of Arthur a...
Figure 85: Synthesis of mannosamine ether lipid 85.6 [254].
Figure 86: A) Synthesis of glucosamine ether lipids with a non-natural ʟ-glucosamine moiety; B) synthesis of e...
Figure 87: A) Structure of the most efficient anticancer agents 87.1–87.4 featuring a diamino glyco ether lipi...
Figure 88: A) Synthesis of diamino glyco ether lipid 87.4; B) synthesis of bis-glycosylated ether lipid 88.10 [256]....
Figure 89: Synthesis of triamino ether lipid 89.4 [260].
Figure 90: Synthesis of chlorambucil conjugate 90.7 [261].
Figure 91: Three main methods for the preparation of glycerol ether lipid 91.3; A) from solketal and via a tri...
Figure 92: Four different methods for the installation of the phosphocholine polar head group; A) method using...
Figure 93: Illustration of two methods for the installation of saccharides or aminosaccharides; A) O-glycosyla...
A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes
- Alena V. Dmitrieva,
- Oleg A. Levitskiy,
- Yuri K. Grishin and
- Tatiana V. Magdesieva
Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41
- employing chiral auxiliaries [4][5] and asymmetric phase-transfer catalysis [6][7]. The former approach is commonly based on the application of chiral derivatives of glycine containing structurally diverse chiral auxiliaries, both cyclic [8][9][10][11] and acyclic [12][13]. Transition-metal complexes
Graphical Abstract
Scheme 1: Selected examples of the chiral ligands used for synthesis of the Ni(II)–Schiff base complexes.
Scheme 2: Synthesis of the chiral ligand L7 and its Ni(II) complexes with glycine, serine, dehydroalanine, an...
Figure 1: Fragment of the NOESY spectrum of the ʟ-(oBrCysNi)L7 complex indicating the correlation between the...
Figure 2: Low-gradient isosurfaces with low densities (blue color of the isosurface corresponds to the hydrog...
Figure 3: Saturated solutions of (GlyNi)L1 (left) and (GlyNi)L7 (right) in diethyl ether.
Figure 4: The CV curves observed for (GlyNi)L7 and (ΔAlaNi)L7 in the anodic and cathodic regions (Pt, CH3CN, ...
Menadione: a platform and a target to valuable compounds synthesis
- Acácio S. de Souza,
- Ruan Carlos B. Ribeiro,
- Dora C. S. Costa,
- Fernanda P. Pauli,
- David R. Pinho,
- Matheus G. de Moraes,
- Fernando de C. da Silva,
- Luana da S. M. Forezi and
- Vitor F. Ferreira
Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43
Graphical Abstract
Figure 1: Natural bioactive naphthoquinones.
Figure 2: Chemical structures of vitamins K.
Figure 3: Redox cycle of menadione.
Scheme 1: Selected approaches for menadione synthesis using silver(I) as a catalyst.
Scheme 2: Methylation approaches for the preparation of menadione from 1,4-naphthoquinone using tert-butyl hy...
Scheme 3: Methylation approach of 1,4-naphthoquinone using i) rhodium complexes/methylboronic acid and ii) bi...
Scheme 4: Synthesis of menadione (10) from itaconic acid.
Scheme 5: Menadione synthesis via Diels–Alder reaction.
Scheme 6: Synthesis of menadione (10) using p-cresol as a synthetic precursor.
Scheme 7: Synthesis of menadione (10) via demethoxycarbonylating annulation of methyl methacrylate.
Scheme 8: Furan 34 used as a diene in a Diels–Alder reaction for the synthesis of menadione (10).
Scheme 9: o-Toluidine as a dienophile in a Diels–Alder reaction for the synthesis of menadione (10).
Scheme 10: Representation of electrochemical synthesis of menadione.
Figure 4: Reaction sites and reaction types of menadione as substrate.
Scheme 11: DBU-catalyzed epoxidation of menadione (10).
Scheme 12: Phase-transfer catalysis for the epoxidation of menadione.
Scheme 13: Menadione epoxidation using a hydroperoxide derived from (+)-norcamphor.
Scheme 14: Enantioselective Diels–Alder reaction for the synthesis of asymmetric quinone 50 catalyzed by a chi...
Scheme 15: Optimized reaction conditions for the synthesis of anthra[9,1-bc]pyranone.
Scheme 16: Synthesis of anthra[9,1-bc]furanone, anthra[9,1-bc]pyridine, and anthra[9,1-bc]pyrrole derivatives.
Scheme 17: Synthesis of derivatives employing protected trienes.
Scheme 18: Synthesis of cyclobutene derivatives of menadione.
Scheme 19: Menadione reduction reactions using sodium hydrosulfite.
Scheme 20: Green methodology for menadiol synthesis and pegylation.
Scheme 21: Menadione reduction by 5,6-O-isopropylidene-ʟ-ascorbic acid under UV light irradiation.
Scheme 22: Selected approaches of menadione hydroacetylation to diacetylated menadiol.
Scheme 23: Thiele–Winter reaction catalyzed by Bi(OTf)3.
Scheme 24: Carbonyl condensation of menadione using resorcinol and a hydrazone derivative.
Scheme 25: Condensation reaction of menadione with thiosemicarbazide.
Scheme 26: Condensation reaction of menadione with acylhydrazides.
Scheme 27: Menadione derivatives functionalized with organochalcogens.
Scheme 28: Synthesis of selenium-menadione conjugates derived from chloromethylated menadione 84.
Scheme 29: Menadione alkylation by the Kochi–Anderson method.
Scheme 30: Menadione alkylation by diacids.
Scheme 31: Menadione alkylation by heterocycles-substituted carboxylic acids.
Scheme 32: Menadione alkylation by bromoalkyl-substituted carboxylic acids.
Scheme 33: Menadione alkylation by complex carboxylic acids.
Scheme 34: Kochi–Anderson method variations for the menadione alkylation via oxidative decarboxylation of carb...
Scheme 35: Copper-catalyzed menadione alkylation via free radicals.
Scheme 36: Nickel-catalyzed menadione cyanoalkylation.
Scheme 37: Iron-catalyzed alkylation of menadione.
Scheme 38: Selected approaches to menadione alkylation.
Scheme 39: Menadione acylation by photo-Friedel–Crafts acylation reported by Waske and co-workers.
Scheme 40: Menadione acylation by Westwood procedure.
Scheme 41: Synthesis of 3-benzoylmenadione via metal-free TBAI/TBHP system.
Scheme 42: Michael-type addition of amines to menadione reported by Kallmayer.
Scheme 43: Synthesis of amino-menadione derivatives using polyalkylamines.
Scheme 44: Selected examples for the synthesis of different amino-substituted menadione derivatives.
Scheme 45: Selected examples of Michael-type addition of complex amines to menadione (10).
Scheme 46: Addition of different natural α-amino acids to menadione.
Scheme 47: Michael-type addition of amines to menadione using silica-supported perchloric acid.
Scheme 48: Indolylnaphthoquinone or indolylnaphthalene-1,4-diol synthesis reported by Yadav et al.
Scheme 49: Indolylnaphthoquinone synthesis reported by Tanoue and co-workers.
Scheme 50: Indolylnaphthoquinone synthesis from menadione by Escobeto-González and co-workers.
Scheme 51: Synthesis of menadione analogues functionalized with thiols.
Scheme 52: Synthesis of menadione-derived symmetrical derivatives through reaction with dithiols.
Scheme 53: Mercaptoalkyl acids as nucleophiles in Michael-type addition reaction to menadione.
Scheme 54: Reactions of menadione (10) with cysteine derivatives for the synthesis of quinoproteins.
Scheme 55: Synthesis of menadione-glutathione conjugate 152 by Michael-type addition.
New advances in asymmetric organocatalysis
- Radovan Šebesta
Beilstein J. Org. Chem. 2022, 18, 240–242, doi:10.3762/bjoc.18.28
- cyclopropenimines exemplify Brønsted base organocatalysts that are useful for diverse reactions not easily accessible by other means. Here, Lambert and co-workers employed this type of catalyst in the formation of pyroglutamates via enantioselective Michael addition of amino ester imines [22]. Phase-transfer
- catalysis relies on the deprotonation of one of the substrates, but basic conditions may limit the applicability of this methodology. A unique base-free variant of chiral phase-transfer catalytic alkylation of 2-oxindoles was developed by Connon and co-workers [23]. Pentacarboxycyclopentadienes are a unique
Base-free enantioselective SN2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis
- Mili Litvajova,
- Emiliano Sorrentino,
- Brendan Twamley and
- Stephen J. Connon
Beilstein J. Org. Chem. 2021, 17, 2287–2294, doi:10.3762/bjoc.17.146
- synthesis of a potent CRTH2 receptor antagonist. Keywords: alkylation; base-free; cinchona alkaloids; CRTH2 antagonist; hydrogen-bonding; oxindole; phase-transfer catalysis; Introduction The 2-oxindole scaffold is an important motif present in a myriad of natural products. Among 2-oxidole derivatives, 3,3
- this approach is significantly enhanced when both the substituents at the 3-position are modifiable as much as possible to facilitate further transformations. In this context, we realised that phase-transfer catalysis, due to its operational simplicity and utility in mediating reactions involving
- charged intermediates, could be an excellent methodology for the enantioselective SN2 alkylation of enolates derived from the 2-oxindole core [13][14][15][16][17][18][19][20][21][22][23]. In recent years, several examples regarding the alkylation of 3-subsituted-2-oxindoles, via asymmetric phase-transfer
Graphical Abstract
Figure 1: The importance of the 3,3-spirooxindole core and its access through enantioselective enolate alkyla...
Scheme 1: A) SN2 alkylation of 3-subtituted-2-oxindoles not readily functionalisable; B) Previous work: enant...
Figure 2: Substrate scope. aIsolated yield. bDetermined by CSP-HPLC. cValue in brackets refers to reaction co...
Scheme 2: Enantioselective synthesis of a CRTH2 receptor antagonist.
Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines
- Zara M. Seibel,
- Jeffrey S. Bandar and
- Tristan H. Lambert
Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134
- only up to 84% ee [36]. Phase-transfer catalysis has been employed for the enantioselective addition of an alanine imine derivative, although the selectivity achieved in this case was only 64% ee [37]. In a related work, enantioselectivities of up to 90% ee were realized, but the procedure required an
Graphical Abstract
Figure 1: Strategy for the synthesis of glutamate and pyroglutamate derivatives and several natural products ...
Figure 2: Effect of the aryl substituent on reaction efficiency and selectivity.
Figure 3: Proposed transition state model.
Development of N-F fluorinating agents and their fluorinations: Historical perspective
- Teruo Umemoto,
- Yuhao Yang and
- Gerald B. Hammond
Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123
Graphical Abstract
Scheme 1: Fluorination with N-F amine 1-1.
Scheme 2: Preparation of N-F amine 1-1.
Scheme 3: Reactions of N-F amine 1-1.
Scheme 4: Synthesis of N-F perfluoroimides 2-1 and 2-2.
Scheme 5: Synthesis of 1-fluoro-2-pyridone (3-1).
Scheme 6: Fluorination with 1-fluoro-2-pyridone (3-1).
Figure 1: Synthesis of N-F sulfonamides 4-1a–g.
Scheme 7: Fluorination with N-F reagent 4-1b,c,f.
Scheme 8: Fluorination of alkenyllithiums with N-F 4-1h.
Scheme 9: Synthesis of N-fluoropyridinium triflate (5-4a).
Scheme 10: Synthetic methods for N-F-pyridinium salts.
Figure 2: Synthesis of various N-fluoropyridinium salts. Note: athis yield was the one by the improved method...
Scheme 11: Fluorination power order of N-fluoropyridinium salts.
Scheme 12: Fluorinations with N-F salts 5-4.
Scheme 13: Fluorination of Corey lactone 5-7 with N-F-bis(methoxymethyl) salt 5-4l.
Scheme 14: Fluorination with NFPy.
Scheme 15: Synthesis of the N-F reagent, N-fluoroquinuclidinium fluoride (6-1).
Scheme 16: Fluorinations achieved with N-F fluoride 6-1.
Scheme 17: Synthesis of N-F imides 7-1a–g.
Scheme 18: Fluorination with (CF3SO2)2NF, 7-1a.
Scheme 19: Fluorination reactions of various substrates with 7-1a.
Scheme 20: Synthesis of N-F triflate 8-1.
Scheme 21: Synthesis of chiral N-fluoro sultams 9-1 and 9-2.
Scheme 22: Fluorination with chiral N-fluoro sultams 9-1 and 9-2.
Scheme 23: Synthesis of saccharin-derived N-fluorosultam 10-2.
Scheme 24: Fluorination with N-fluorosultam 10-2.
Scheme 25: Synthesis of N-F reagent 11-2.
Scheme 26: Fluorination with N-F reagent 11-2.
Scheme 27: Synthesis and reaction of N-fluorolactams 12-1.
Scheme 28: Synthesis of NFOBS 13-2.
Scheme 29: Fluorination with NFOBS 13-2.
Scheme 30: Synthesis of NFSI (14-2).
Scheme 31: Fluorination with NFSI 14-2.
Scheme 32: Synthesis of N-fluorosaccharin (15-1) and N-fluorophthalimide (15-2).
Scheme 33: Synthesis of N-F salts 16-3.
Scheme 34: Fluorination with N-F salts 16-3.
Figure 3: Monofluorination with Selectfluor (16-3a).
Figure 4: Difluorination with Selectfluor (16-3a).
Scheme 35: Transfer fluorination of Selectfluor (16-3a).
Scheme 36: Fluorination of substrates with Selectfluor (16-3a).
Scheme 37: Synthesis of chiral N-fluoro-sultam 17-2.
Scheme 38: Asymmetric fluorination with chiral 17-2.
Figure 5: Synthesis of Zwitterionic N-fluoropyridinium salts 18-2a–h.
Scheme 39: Fluorinating power order of zwitterionic N-fluoropyridinium salts.
Scheme 40: Fluorination with zwitterionic 18-2.
Scheme 41: Activation of salt 18-2h with TfOH.
Scheme 42: Synthesis of NFTh, 19-2.
Scheme 43: Fluorination with NFTh, 19-2.
Scheme 44: Synthesis of 3-fluorobenzo-1,2,3-oxathiazin-4-one 2,2-dioxide (20-2).
Scheme 45: Fluorination with 20-2.
Scheme 46: Synthesis of N-F amide 21-3.
Scheme 47: Fluorination with N-F amide 21-2.
Scheme 48: Synthesis of N,N’-difluorodiazoniabicyclo[2.2.2]octane salts 22-1.
Scheme 49: One-pot synthesis of N,N’-difluoro-1,4-diazoniabicyclo[2.2.2]octane bistetrafluoroborate salt (22-1d...
Figure 6: Fluorination of anisole with 22-1a, d, e.
Scheme 50: Fluorination with N,N’-diF bisBF4 22-1d.
Scheme 51: Synthesis of bis-N-F reagents 23-1–5.
Scheme 52: Fluorination with 23-2, 4, 5.
Figure 7: Synthesis of N,N’-difluorobipyridinium salts 24-2.
Figure 8: Controlled fluorination of N,N’-diF 24-2.
Scheme 53: Fluorinating power of N,N’-diF salts 24-2 and N-F salt 5-4a.
Scheme 54: Fluorination reactions with SynfluorTM (24-2b).
Scheme 55: Additional fluorination reactions with SynfluorTM (24-2b).
Scheme 56: Synthesis of N-F 25-1.
Scheme 57: Fluorination of polycyclic aromatics with 25-1.
Scheme 58: Synthesis of 26-1 and dimethyl analog 26-2.
Scheme 59: Fluorination with reagents 26-1, 26-2, 1-1, and 26-3.
Scheme 60: Synthesis of N-F reagent 27-2.
Scheme 61: Synthesis of chiral N-F reagents 27-6.
Scheme 62: Synthesis of chiral N-F 27-7–9.
Scheme 63: Asymmetric fluorination with 27-6.
Scheme 64: Synthesis of chiral N-F reagents 28-3.
Scheme 65: Asymmetric fluorination with 28-3.
Scheme 66: Synthesis of chiral N-F reagents 28-7.
Figure 9: Asymmetric fluorination with 28-7.
Scheme 67: In situ formation of N-fluorinated cinchona alkaloids with SelectfluorTM.
Scheme 68: Asymmetric fluorination with N-F alkaloids formed in situ.
Scheme 69: Synthesis of N-fluorocinchona alkaloids with Selectfluor.
Scheme 70: Asymmetric fluorination with 30-1–4.
Scheme 71: Transfer fluorination from various N-F reagents.
Figure 10: Asymmetric fluorination of silyl enol ethers.
Scheme 72: Synthesis of N-fluoro salt 32-2.
Scheme 73: Reactivity of N-fluorotriazinium salt 32-2.
Scheme 74: Synthesis of bulky N-fluorobenzenesulfonimide NFBSI 33-3.
Scheme 75: Comparison of NFSI and NFBSI.
Scheme 76: Synthesis of p-substituted N-fluorobenzenesulfonimides 34-3.
Figure 11: Asymmetric fluorination with 34-3 and a chiral catalyst 34-4.
Scheme 77: 1,4-Fluoroamination with Selecfluor and a chiral catalyst.
Figure 12: Asymmetric fluoroamination with 35-5a, b.
Scheme 78: Synthesis of Selectfluor analogs 35-5a, b.
Scheme 79: Synthesis of chiral dicationic DABCO-based N-F reagents 36-5.
Scheme 80: Asymmetric fluorocyclization with chiral 36-5b.
Scheme 81: Synthesis of chiral 37-2a,b.
Scheme 82: Asymmetric fluorination with chiral 37-2a,b.
Scheme 83: Asymmetric fluorination with chiral 37-2b.
Scheme 84: Reaction of indene with chiral 37-2a,b.
Scheme 85: Synthesis of Me-NFSI, 38-2.
Scheme 86: Fluorination of active methine compounds with Me-NFSI.
Scheme 87: Fluorination of malonates with Me-NFSI.
Scheme 88: Fluorination of keto esters with Me-NFSI.
Scheme 89: Synthesis of N-F 39-3 derived from the ethylene-bridged Tröger’s base.
Scheme 90: Fluorine transfer from N-F 39-3.
Scheme 91: Fluorination with N-F 39-3.
Scheme 92: Synthesis of SelectfluorCN.
Scheme 93: Bistrifluoromethoxylation of alkenes using SelectfluorCN.
Figure 13: Synthesis of NFAS 41-2.
Scheme 94: Radical fluorination with different N-F reagents.
Scheme 95: Radical fluorination of alkenes with NFAS 41-2.
Scheme 96: Radical fluorination of alkenes with NFAS 41-2f.
Scheme 97: Decarboxylative fluorination with NFAS 41-2a,f.
Scheme 98: Fluorine plus detachment (FPD).
Figure 14: FPD values of representative N-F reagents in CH2Cl2 and CH3CN (in parentheses). Adapted with permis...
Scheme 99: N-F homolytic bond dissociation energy (BDE).
Figure 15: BDE values of representative N-F reagents in CH3CN. Adapted with permission from ref. [127]. Copyright 2...
Figure 16: Quantitative reactivity scale for popular N-F reagents. Adapted with permission from ref. [138], publish...
Scheme 100: SET and SN2 mechanisms.
Scheme 101: Radical clock reactions.
Scheme 102: Reaction of potassium enolate of citronellic ester with N-F reagents, 10-1, NFSI, and 8-1.
Scheme 103: Reaction of compound IV with Selectfluor (OTf) and NFSI.
Scheme 104: Reaction of TEMPO with Selecfluor.
The preparation and properties of 1,1-difluorocyclopropane derivatives
- Kymbat S. Adekenova,
- Peter B. Wyatt and
- Sergazy M. Adekenov
Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25
- were increased when potassium fluoride and 18-crown-6 were added to the reaction mixture [20]. Dehydrohalogenation of dichlorodifluoromethane under phase-transfer catalysis: Difluorocarbene can be generated from chlorodifluoromethane by phase-transfer catalysis (PTC) through the reaction with NaOH or
Graphical Abstract
Scheme 1: Synthesis of 1,1-difluoro-2,3-dimethylcyclopropane (2).
Scheme 2: Cyclopropanation via dehydrohalogenation of chlorodifluoromethane.
Scheme 3: Difluorocyclopropanation of methylstyrene 7 using dibromodifluoromethane and zinc.
Scheme 4: Synthesis of difluorocyclopropanes from the reaction of dibromodifluoromethane and triphenylphosphi...
Scheme 5: Generation of difluorocarbene in a catalytic two-phase system and its addition to tetramethylethyle...
Scheme 6: The reaction of methylstyrene 7 with chlorodifluoromethane (11) in the presence of a tetraarylarson...
Scheme 7: Pyrolysis of sodium chlorodifluoroacetate (12) in refluxing diglyme in the presence of alkene 13.
Scheme 8: Synthesis of boron-substituted gem-difluorocyclopropanes 16.
Scheme 9: Addition of sodium bromodifluoroacetate (17) to alkenes.
Scheme 10: Addition of sodium bromodifluoroacetate (17) to silyloxy-substituted cyclopropanes 20.
Scheme 11: Synthesis of difluorinated nucleosides.
Scheme 12: Addition of butyl acrylate (26) to difluorocarbene generated from TFDA (25).
Scheme 13: Addition of difluorocarbene to propargyl esters 27 and conversion of the difluorocyclopropenes 28 t...
Scheme 14: The generation of difluorocyclopropanes using MDFA 30.
Scheme 15: gem-Difluorocyclopropanation of styrene (32) using difluorocarbene generated from TMSCF3 (31) under...
Scheme 16: Synthesis of a gem-difluorocyclopropane derivative using HFPO (41) as a source of difluorocarbene.
Scheme 17: Cyclopropanation of (Z)-2-butene in the presence of difluorodiazirine (44).
Scheme 18: The cyclopropanation of 1-octene (46) using Seyferth's reagent (45) as a source of difluorocarbene.
Scheme 19: Alternative approaches for the difluorocarbene synthesis from trimethyl(trifluoromethyl)tin (48).
Scheme 20: Difluorocyclopropanation of cyclohexene (49).
Scheme 21: Synthesis of difluorocyclopropane derivative 53 using bis(trifluoromethyl)cadmium (51) as the diflu...
Scheme 22: Addition of difluorocarbene generated from tris(trifluoromethyl)bismuth (54).
Scheme 23: Addition of a stable (trifluoromethyl)zinc reagent to styrenes.
Scheme 24: The preparation of 2,2-difluorocyclopropanecarboxylic acids of type 58.
Scheme 25: Difluorocyclopropanation via Michael cyclization.
Scheme 26: Difluorocyclopropanation using N-acylimidazolidinone 60.
Scheme 27: Difluorocyclopropanation through the cyclization of phenylacetonitrile (61) and 1,2-dibromo-1,1-dif...
Scheme 28: gem-Difluoroolefins 64 for the synthesis of functionalized cyclopropanes 65.
Scheme 29: Preparation of aminocyclopropanes 70.
Scheme 30: Synthesis of fluorinated methylenecyclopropane 74 via selenoxide elimination.
Scheme 31: Reductive dehalogenation of (1R,3R)-75.
Scheme 32: Synthesis of chiral monoacetates by lipase catalysis.
Scheme 33: Transformation of (±)-trans-81 using Rhodococcus sp. AJ270.
Scheme 34: Transformation of (±)-trans-83 using Rhodococcus sp. AJ270.
Scheme 35: Hydrogenation of difluorocyclopropenes through enantioselective hydrocupration.
Scheme 36: Enantioselective transfer hydrogenation of difluorocyclopropenes with a Ru-based catalyst.
Scheme 37: The thermal transformation of trans-1,2-dichloro-3,3-difluorocyclopropane (84).
Scheme 38: cis–trans-Epimerization of 1,1-difluoro-2,3-dimethylcyclopropane.
Scheme 39: 2,2-Difluorotrimethylene diradical intermediate.
Scheme 40: Ring opening of stereoisomers 88 and 89.
Scheme 41: [1,3]-Rearrangement of alkenylcyclopropanes 90–92.
Scheme 42: Thermolytic rearrangement of 2,2-difluoro-1-vinylcyclopropane (90).
Scheme 43: Thermal rearrangement for ethyl 3-(2,2-difluoro)-3-phenylcyclopropyl)acrylates 93 and 95.
Scheme 44: Possible pathways of the ring opening of 1,1-difluoro-2-vinylcyclopropane.
Scheme 45: Equilibrium between 1,1-difluoro-2-methylenecyclopropane (96) and (difluoromethylene)cyclopropane 97...
Scheme 46: Ring opening of substituted 1,1-difluoro-2,2-dimethyl-3-methylenecyclopropane 98.
Scheme 47: 1,1-Difluorospiropentane rearrangement.
Scheme 48: Acetolysis of (2,2-difluorocyclopropyl)methyl tosylate (104) and (1,1-difluoro-2-methylcyclopropyl)...
Scheme 49: Ring opening of gem-difluorocyclopropyl ketones 106 and 108 by thiolate nucleophiles.
Scheme 50: Hydrolysis of gem-difluorocyclopropyl acetals 110.
Scheme 51: Ring-opening reaction of 2,2-difluorocyclopropyl ketones 113 in the presence of ionic liquid as a s...
Scheme 52: Ring opening of gem-difluorocyclopropyl ketones 113a by MgI2-initiated reaction with diarylimines 1...
Scheme 53: Ring-opening reaction of gem-difluorocyclopropylstannanes 117.
Scheme 54: Preparation of 1-fluorovinyl vinyl ketone 123 and the synthesis of 2-fluorocyclopentenone 124. TBAT...
Scheme 55: Iodine atom-transfer ring opening of 1,1-difluoro-2-(1-iodoalkyl)cyclopropanes 125a–c.
Scheme 56: Ring opening of bromomethyl gem-difluorocyclopropanes 130 and formation of gem-difluoromethylene-co...
Scheme 57: Ring-opening aerobic oxidation reaction of gem-difluorocyclopropanes 132.
Scheme 58: Dibrominative ring-opening functionalization of gem-difluorocyclopropanes 134.
Scheme 59: The selective formation of (E,E)- and (E,Z)-fluorodienals 136 and 137 from difluorocyclopropyl acet...
Scheme 60: Proposed mechanism for the reaction of difluoro(methylene)cyclopropane 139 with Br2.
Scheme 61: Thermal rearrangement of F2MCP 139 and iodine by CuI catalysis.
Scheme 62: Synthesis of 2-fluoropyrroles 142.
Scheme 63: Ring opening of gem-difluorocyclopropyl ketones 143 mediated by BX3.
Scheme 64: Lewis acid-promoted ring-opening reaction of 2,2-difluorocyclopropanecarbonyl chloride (148).
Scheme 65: Ring-opening reaction of the gem-difluorocyclopropyl ketone 106 by methanolic KOH.
Scheme 66: Hydrogenolysis of 1,1-difluoro-3-methyl-2-phenylcyclopropane (151).
Scheme 67: Synthesis of monofluoroalkenes 157.
Scheme 68: The stereoselective Ag-catalyzed defluorinative ring-opening diarylation of 1-trimethylsiloxy-2,2-d...
Scheme 69: Synthesis of 2-fluorinated allylic compounds 162.
Scheme 70: Pd-catalyzed cross-coupling reactions of gem-difluorinated cyclopropanes 161.
Scheme 71: The (Z)-selective Pd-catalyzed ring-opening sulfonylation of 2-(2,2-difluorocyclopropyl)naphthalene...
Figure 1: Structures of zosuquidar hydrochloride and PF-06700841.
Scheme 72: Synthesis of methylene-gem-difluorocyclopropane analogs of nucleosides.
Figure 2: Anthracene-difluorocyclopropane hybrid derivatives.
Figure 3: Further examples of difluorcyclopropanes in modern drug discovery.
Recent developments in enantioselective photocatalysis
- Callum Prentice,
- James Morrisson,
- Andrew D. Smith and
- Eli Zysman-Colman
Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197
- :33 rr) but this example does demonstrate an interesting proof of concept with potential for the development of processes using alternative bifunctional catalysts. Phase-transfer catalysis Phase-transfer catalysis (PTC) is another non-covalent mode of catalysis that has been combined with
Graphical Abstract
Scheme 1: Amine/photoredox-catalysed α-alkylation of aldehydes with alkyl bromides bearing electron-withdrawi...
Scheme 2: Amine/HAT/photoredox-catalysed α-functionalisation of aldehydes using alkenes.
Scheme 3: Amine/cobalt/photoredox-catalysed α-functionalisation of ketones and THIQs.
Scheme 4: Amine/photoredox-catalysed α-functionalisation of aldehydes or ketones with imines. (a) Using keton...
Scheme 5: Bifunctional amine/photoredox-catalysed enantioselective α-functionalisation of aldehydes.
Scheme 6: Bifunctional amine/photoredox-catalysed α-functionalisation of aldehydes using amine catalysts via ...
Scheme 7: Amine/photoredox-catalysed RCA of iminium ion intermediates. (a) Synthesis of quaternary stereocent...
Scheme 8: Bifunctional amine/photoredox-catalysed RCA of enones in a radical chain reaction initiated by an i...
Scheme 9: Bifunctional amine/photoredox-catalysed RCA reactions of iminium ions with different radical precur...
Scheme 10: Bifunctional amine/photoredox-catalysed radical cascade reactions between enones and alkenes with a...
Scheme 11: Amine/photocatalysed photocycloadditions of iminium ion intermediates. (a) External photocatalyst u...
Scheme 12: Amine/photoredox-catalysed addition of acrolein (94) to iminium ions.
Scheme 13: Dual NHC/photoredox-catalysed acylation of THIQs.
Scheme 14: NHC/photocatalysed spirocyclisation via photoisomerisation of an extended Breslow intermediate.
Scheme 15: CPA/photoredox-catalysed aza-pinacol cyclisation.
Scheme 16: CPA/photoredox-catalysed Minisci-type reaction between azaarenes and α-amino radicals.
Scheme 17: CPA/photoredox-catalysed radical additions to azaarenes. (a) α-Amino radical or ketyl radical addit...
Scheme 18: CPA/photoredox-catalysed reduction of azaarene-derived substrates. (a) Reduction of ketones. (b) Ex...
Scheme 19: CPA/photoredox-catalysed radical coupling reactions of α-amino radicals with α-carbonyl radicals. (...
Scheme 20: CPA/photoredox-catalysed Povarov reaction.
Scheme 21: CPA/photoredox-catalysed reactions with imines. (a) Decarboxylative imine generation followed by Po...
Scheme 22: Bifunctional CPA/photocatalysed [2 + 2] photocycloadditions.
Scheme 23: PTC/photocatalysed oxygenation of 1-indanone-derived β-keto esters.
Scheme 24: PTC/photoredox-catalysed perfluoroalkylation of 1-indanone-derived β-keto esters via a radical chai...
Scheme 25: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 26: Bifunctional hydrogen bonding/photocatalysed intramolecular RCA cyclisation of a quinolone.
Scheme 27: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 28: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloaddition reactions. (a) First use of...
Scheme 29: Bifunctional hydrogen bonding/photocatalysed deracemisation of allenes.
Scheme 30: Bifunctional hydrogen bonding/photocatalysed deracemisation reactions. (a) Deracemisation of sulfox...
Scheme 31: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloaddition of coumarins....
Scheme 32: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloadditions of quinolones. (a) Intramo...
Scheme 33: Hydrogen bonding/photocatalysed formal arylation of benzofuranones.
Scheme 34: Hydrogen bonding/photoredox-catalysed dehalogenative protonation of α,α-chlorofluoro ketones.
Scheme 35: Hydrogen bonding/photoredox-catalysed reductions. (a) Reduction of 1,2-diketones. (b) Reduction of ...
Scheme 36: Hydrogen bonding/HAT/photocatalysed deracemisation of cyclic ureas.
Scheme 37: Hydrogen bonding/HAT/photoredox-catalysed synthesis of cyclic sulfonamides.
Scheme 38: Hydrogen bonding/photoredox-catalysed reaction between imines and indoles.
Scheme 39: Chiral cation/photoredox-catalysed radical coupling of two α-amino radicals.
Scheme 40: Chiral phosphate/photoredox-catalysed hydroetherfication of alkenols.
Scheme 41: Chiral phosphate/photoredox-catalysed synthesis of pyrroloindolines.
Scheme 42: Chiral anion/photoredox-catalysed radical cation Diels–Alder reaction.
Scheme 43: Lewis acid/photoredox-catalysed cycloadditions of carbonyls. (a) Formal [2 + 2] cycloaddition of en...
Scheme 44: Lewis acid/photoredox-catalysed RCA reaction using a scandium Lewis acid between α-amino radicals a...
Scheme 45: Lewis acid/photoredox-catalysed RCA reaction using a copper Lewis acid between α-amino radicals and...
Scheme 46: Lewis acid/photoredox-catalysed synthesis of 1,2-amino alcohols from aldehydes and nitrones using a...
Scheme 47: Lewis acid/photocatalysed [2 + 2] photocycloadditions of enones and alkenes.
Scheme 48: Meggers’s chiral-at-metal catalysts.
Scheme 49: Lewis acid/photoredox-catalysed α-functionalisation of ketones with alkyl bromides bearing electron...
Scheme 50: Bifunctional Lewis acid/photoredox-catalysed radical coupling reaction using α-chloroketones and α-...
Scheme 51: Lewis acid/photocatalysed RCA of enones. (a) Using aldehydes as acyl radical precursors. (b) Other ...
Scheme 52: Bifunctional Lewis acid/photocatalysis for a photocycloaddition of enones.
Scheme 53: Lewis acid/photoredox-catalysed RCA reactions of enones using DHPs as radical precursors.
Scheme 54: Lewis acid/photoredox-catalysed functionalisation of β-ketoesters. (a) Hydroxylation reaction catal...
Scheme 55: Bifunctional copper-photocatalysed alkylation of imines.
Scheme 56: Copper/photocatalysed alkylation of imines. (a) Bifunctional copper catalysis using α-silyl amines....
Scheme 57: Bifunctional Lewis acid/photocatalysed intramolecular [2 + 2] photocycloaddition.
Scheme 58: Bifunctional Lewis acid/photocatalysed [2 + 2] photocycloadditions (a) Intramolecular cycloaddition...
Scheme 59: Bifunctional Lewis acid/photocatalysed rearrangement of 2,4-dieneones.
Scheme 60: Lewis acid/photocatalysed [2 + 2] cycloadditions of cinnamate esters and styrenes.
Scheme 61: Nickel/photoredox-catalysed arylation of α-amino acids using aryl bromides.
Scheme 62: Nickel/photoredox catalysis. (a) Desymmetrisation of cyclic meso-anhydrides using benzyl trifluorob...
Scheme 63: Nickel/photoredox catalysis for the acyl-carbamoylation of alkenes with aldehydes using TBADT as a ...
Scheme 64: Bifunctional copper/photoredox-catalysed C–N coupling between α-chloro amides and carbazoles or ind...
Scheme 65: Bifunctional copper/photoredox-catalysed difunctionalisation of alkenes with alkynes and alkyl or a...
Scheme 66: Copper/photoredox-catalysed decarboxylative cyanation of benzyl phthalimide esters.
Scheme 67: Copper/photoredox-catalysed cyanation reactions using TMSCN. (a) Propargylic cyanation (b) Ring ope...
Scheme 68: Palladium/photoredox-catalysed allylic alkylation reactions. (a) Using alkyl DHPs as radical precur...
Scheme 69: Manganese/photoredox-catalysed epoxidation of terminal alkenes.
Scheme 70: Chromium/photoredox-catalysed allylation of aldehydes.
Scheme 71: Enzyme/photoredox-catalysed dehalogenation of halolactones.
Scheme 72: Enzyme/photoredox-catalysed dehalogenative cyclisation.
Scheme 73: Enzyme/photoredox-catalysed reduction of cyclic imines.
Scheme 74: Enzyme/photocatalysed enantioselective reduction of electron-deficient alkenes as mixtures of (E)/(Z...
Scheme 75: Enzyme/photoredox catalysis. (a) Deacetoxylation of cyclic ketones. (b) Reduction of heteroaromatic...
Scheme 76: Enzyme/photoredox-catalysed synthesis of indole-3-ones from 2-arylindoles.
Scheme 77: Enzyme/HAT/photoredox catalysis for the DKR of primary amines.
Scheme 78: Bifunctional enzyme/photoredox-catalysed benzylic C–H hydroxylation of trifluoromethylated arenes.
Recent applications of chiral calixarenes in asymmetric catalysis
- Mustafa Durmaz,
- Erkan Halay and
- Selahattin Bozkurt
Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117
- reaction in the following order: phase-transfer catalysis, Henry reaction, Suzuki–Miyaura cross-coupling and Tsuji–Trost allylic substitution, hydrogenation, Michael addition, aldol and multicomponent Biginelli reactions, epoxidation, Meerwein−Ponndorf−Verley reduction, aza-Diels−Alder and epoxide ring
- -opening reaction. Review Phase-transfer catalysis For the past three decades, asymmetric phase-transfer catalysis utilizing chiral quaternary ammonium salts has attracted great interest as a synthetic strategy since it provides quick access to a large number of enantiopure compounds employing only
- asymmetric phase-transfer catalysis based on inherently chiral calix[4]arenes, although the asymmetric induction observed remained moderate. Su et al. demonstrated a new approach for the design of a chiral binary integrative phase-transfer catalyst consisting of p-tert-butylcalix[4]arene and a cinchonine
Graphical Abstract
Figure 1: Inherently chiral calix[4]arene-based phase-transfer catalysts.
Scheme 1: Asymmetric alkylations of 3 catalyzed by (±)-1 and (±)-2 under phase-transfer conditions.
Scheme 2: Synthesis of chiral calix[4]arene-based phase-transfer catalyst 7 and structure of O’Donnell’s N-be...
Scheme 3: Asymmetric alkylation of glycine derivative 3 catalyzed by calixarene-based phase-transfer catalyst ...
Figure 2: Calix[4]arene-amides used as phase-transfer catalysts.
Scheme 4: Phase-transfer alkylation of 3 catalyzed by calixarene-triamide 12.
Scheme 5: Synthesis of inherently chiral calix[4]arenes 20a/20b substituted at the lower rim. Reaction condit...
Scheme 6: Asymmetric Henry reaction between 21 and 22 catalyzed by 20a/20b.
Figure 3: Proposed transition state model of asymmetric Henry reaction.
Scheme 7: Synthesis of enantiomerically pure phosphinoferrocenyl-substituted calixarene ligands 27–29.
Scheme 8: Asymmetric coupling reaction of aryl boronates and aryl halides in the presence of calixarene mono ...
Scheme 9: Asymmetric allylic alkylation in the presence of calix[4]arene ligand (S,S)-29.
Figure 4: Structure of inherently chiral oxazoline calix[4]arenes applied in the palladium-catalyzed Tsuji–Tr...
Scheme 10: Asymmetric Tsuji–Trost reaction in the presence of calix[4]arene ligands 36–39.
Figure 5: BINOL-derived calix[4]arene-diphosphite ligands.
Scheme 11: Asymmetric hydrogenation of 41a and 41b catalyzed by in situ-generated catalysts comprised of [Rh(C...
Figure 6: Inherently chiral calix[4]arene 43 containing a diarylmethanol structure.
Scheme 12: Asymmetric Michael addition reaction of 44 with 45 catalyzed by 43.
Figure 7: Calix[4]arene-based chiral primary amine–thiourea catalysts.
Scheme 13: Asymmetric Michael addition of 48 with 49 catalyzed by 47a and 47b.
Scheme 14: Enantioselective Michael addition of 51 to 52 catalyzed by calix[4]arene thioureas.
Scheme 15: Synthesis of calix[4]arene-based tertiary amine–thioureas 54–56.
Scheme 16: Asymmetric Michael addition of 34 and 57 to nitroalkenes 49 catalyzed by 54b.
Scheme 17: Synthesis of p-tert-butylcalix[4]arene bis-squaramide derivative 64.
Scheme 18: Asymmetric Michael addition catalyzed by 64.
Scheme 19: Synthesis of chiral p-tert-butylphenol analogue 68.
Figure 8: Novel prolinamide organocatalysts based on the calix[4]arene scaffold.
Scheme 20: Asymmetric aldol reactions of 72 with 70 and 71 catalyzed by 69b.
Scheme 21: Synthesis of p-tert-butylcalix[4]arene-based chiral organocatalysts 75 and 78 derived from L-prolin...
Scheme 22: Synthesis of upper rim-functionalized calix[4]arene-based L-proline derivative 83.
Scheme 23: Synthesis and proposed structure of Calix-Pro-MN (86).
Figure 9: Calix[4]arene-based L-proline catalysts containing ester, amide and acid units.
Scheme 24: Synthesis of calix[4]arene-based prolinamide 92.
Scheme 25: Calixarene-based catalysts for the aldol reaction of 21 with 70.
Scheme 26: Asymmetric aldol reactions of 72 with cyclic ketones catalyzed by calix[4]arene-based chiral organo...
Figure 10: A proposed structure for catalyst 92 in H2O.
Scheme 27: Synthetic route for organocatalyst 98.
Scheme 28: Asymmetric aldol reactions catalyzed by 99.
Figure 11: Proposed catalytic environment for catalyst 99 in the presence of water.
Scheme 29: Asymmetric aldol reactions between 94 and 72 catalyzed by 55a.
Scheme 30: Enantioselective Biginelli reactions catalyzed by 69f.
Scheme 31: Synthesis of calix[4]arene–(salen) complexes.
Scheme 32: Enantioselective epoxidation of 108 catalyzed by 107a/107b.
Scheme 33: Synthesis of inherently chiral calix[4]arene catalysts 111 and 112.
Scheme 34: Enantioselective MPV reduction.
Scheme 35: Synthesis of chiral calix[4]arene ligands 116a–c.
Scheme 36: Asymmetric MPV reduction with chiral calix[4]arene ligands.
Scheme 37: Chiral AlIII–calixarene complexes bearing distally positioned chiral substituents.
Scheme 38: Asymmetric MPV reduction in the presence of chiral calix[4]arene diphosphites.
Scheme 39: Synthesis of enantiomerically pure inherently chiral calix[4]arene phosphonic acid.
Scheme 40: Asymmetric aza-Diels–Alder reactions catalyzed by (cR,pR)-121.
Scheme 41: Asymmetric ring opening of epoxides catalyzed by (cR,pR)-121.
Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure
- Denisa Vargová,
- Rastislav Baran and
- Radovan Šebesta
Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42
- based on chiral phase-transfer-catalysis of the Michael addition was also reported [26]. In this context, we decided to develop a synthesis of 4-methylpregabalin from a simple and achiral starting material and build its chirality centers using asymmetric catalysis. This paper describes the synthesis of
Graphical Abstract
Figure 1: Structures of pregabalin and methylpregabalin.
Scheme 1: Synthesis of the nitroalkene 6.
Scheme 2: Catalyst screening in the Michael addition of dimethyl malonate to nitroalkene 6.
Scheme 3: Synthesis of catalysts (Sa,R,R)-C8 and (Sa,S,S)-C8.
Figure 2: Transition state models for the reaction of (R)-6 with dimethyl malonate using catalyst C7 (M06-2X/...
Scheme 4: Synthesis of 4-methylpregabalin (1).
p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests
- Alena A. Vavilova and
- Ivan I. Stoikov
Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188
- ; UV spectroscopy; Introduction Anions play a key role in many biochemical processes [1] as substrates and/or cofactors in enzymatic reactions [2], in the environment (phosphate and nitrate in the ponds provoking their eutrophication) [2][3][4], and in phase-transfer catalysis [5][6]. The dysfunction
Graphical Abstract
Scheme 1: Synthesis of 1,3-di- and tetrasubstituted thiacalix[4]arenes 2 and 3. Conditions: (i) macrocycle 1 ...
Scheme 2: Synthesis of monosubstituted thiacalix[4]arene 4. Conditions: (i) macrocycle 1 (1 equiv), 2-chloro-N...
Scheme 3: Synthesis of tetra- and 1,2-disubstituted thiacalix[4]arenes 5 and 6, respectively. Conditions: (i)...
Figure 1: Investigated hosts 2, 3, 7–10.
Figure 2: UV absorption spectra of the complexation system obtained by titration of the receptor 6 (c(6) = 2....
Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles
- Johannes Schörgenhumer,
- Maximilian Tiffner and
- Mario Waser
Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170
- Johannes Schorgenhumer Maximilian Tiffner Mario Waser Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria 10.3762/bjoc.13.170 Abstract Chiral phase-transfer catalysis is one of the major catalytic principles in asymmetric catalysis. A broad
- ; thioetherification; Introduction In the 1960s and 1970s, the groups of Makosza, Starks, and Brändström pioneered the field of “phase transfer catalysis” by showing the beneficial effect of tetraalkyl-ammonium or -phosphonium salts to facilitate reactions between components that are present in two immiscible phases
- reactions with different electrophiles (Scheme 1). A lot of different examples for such asymmetric α-functionalization reactions of prochiral nucleophiles under asymmetric chiral cation-based phase-transfer catalysis have been reported so far [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Besides
Graphical Abstract
Scheme 1: Generally accepted ion-pairing mechanism between the chiral cation Q+ of a PTC and an enolate and s...
Scheme 2: Reported asymmetric α-fluorination of β-ketoesters 1 using different chiral PTCs.
Scheme 3: Asymmetric α-fluorination of benzofuranones 4 with phosphonium salt PTC F1.
Scheme 4: Asymmetric α-fluorination of 1 with chiral phosphate-based catalysts.
Scheme 5: Anionic PTC-catalysed α-fluorination of enamines 7 and ketones 10.
Scheme 6: PTC-catalysed α-chlorination reactions of β-ketoesters 1.
Scheme 7: Shioiri’s seminal report of the asymmetric α-hydroxylation of 15 with chiral ammonium salt PTCs.
Scheme 8: Asymmetric ammonium salt-catalysed α-hydroxylation using oxygen together with a P(III)-based reduct...
Scheme 9: Asymmetric ammonium salt-catalysed α-photooxygenations.
Scheme 10: Asymmetric ammonium salt-catalysed α-hydroxylations using organic oxygen-transfer reagents.
Scheme 11: Asymmetric triazolium salt-catalysed α-hydroxylation with in situ generated peroxy imidic acid 24.
Scheme 12: Phase-transfer-catalysed dearomatization of phenols and naphthols.
Scheme 13: Ishihara’s ammonium salt-catalysed oxidative cycloetherification.
Scheme 14: Chiral phase-transfer-catalysed α-sulfanylation reactions.
Scheme 15: Chiral phase-transfer-catalysed α-trifluoromethylthiolation of β-ketoesters 1.
Scheme 16: Chiral phase-transfer-catalysed α-amination of β-ketoesters 1 using diazocarboxylates 38.
Scheme 17: Asymmetric α-fluorination of benzofuranones 4 using diazocarboxylates 38 in the presence of phospho...
Scheme 18: Anionic phase-transfer-catalysed α-amination of β-ketoesters 1 with aryldiazonium salts 41.
Scheme 19: Triazolium salt L-catalysed α-amination of different prochiral nucleophiles with in situ activated ...
Scheme 20: Phase-transfer-catalysed Neber rearrangement.
Synthesis of 1-indanones with a broad range of biological activity
- Marika Turek,
- Dorota Szczęsna,
- Marek Koprowski and
- Piotr Bałczewski
Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48
- -indanone derivative 301 in 55% yield under solid–liquid, phase-transfer catalysis conditions [116]. In this synthesis, 2-cyanomethylbenzaldehyde (300) was reacted with cyclopentenone 239 in the presence of powdered K2CO3 and Aliquat® 336 as a catalyst. (Scheme 84). 3 Construction of the 5- and 6-membered
Graphical Abstract
Figure 1: Biologically active 1-indanones and their structural analogues.
Figure 2: Number of papers about (a) 1-indanones, (b) synthesis of 1-indanones.
Scheme 1: Synthesis of 1-indanone (2) from hydrocinnamic acid (1).
Scheme 2: Synthesis of 1-indanone (2) from 3-(2-bromophenyl)propionic acid (3).
Scheme 3: Synthesis of 1-indanones 5 from 3-arylpropionic acids 4.
Scheme 4: Synthesis of kinamycin (9a) and methylkinamycin C (9b).
Scheme 5: Synthesis of trifluoromethyl-substituted arylpropionic acids 12, 1-indanones 13 and dihydrocoumarin...
Scheme 6: Synthesis of 1-indanones 16 from benzoic acids 15.
Scheme 7: Synthesis of 1-indanones 18 from arylpropionic and 3-arylacrylic acids 17.
Scheme 8: The NbCl5-induced one-step synthesis of 1-indanones 22.
Scheme 9: Synthesis of biologically active 1-indanone derivatives 26.
Scheme 10: Synthesis of enantiomerically pure indatraline ((−)-29).
Scheme 11: Synthesis of 1-indanone (2) from the acyl chloride 30.
Scheme 12: Synthesis of the mechanism-based inhibitors 33 of coelenterazine.
Scheme 13: Synthesis of the indane 2-imidazole derivative 37.
Scheme 14: Synthesis of fluorinated PAHs 41.
Scheme 15: Synthesis of 1-indanones 43 via transition metal complexes-catalyzed carbonylative cyclization of m...
Scheme 16: Synthesis of 6-methyl-1-indanone (46).
Scheme 17: Synthesis of 1-indanone (2) from ester 48.
Scheme 18: Synthesis of benzopyronaphthoquinone 51 from the spiro-1-indanone 50.
Scheme 19: Synthesis of the selective endothelin A receptor antagonist 55.
Scheme 20: Synthesis of 1-indanones 60 from methyl vinyl ketone (57).
Scheme 21: Synthesis of 1-indanones 64 from diethyl phthalate 61.
Scheme 22: Synthesis of 1-indanone derivatives 66 from various Meldrum’s acids 65.
Scheme 23: Synthesis of halo 1-indanones 69.
Scheme 24: Synthesis of substituted 1-indanones 71.
Scheme 25: Synthesis of spiro- and fused 1-indanones 73 and 74.
Scheme 26: Synthesis of spiro-1,3-indanodiones 77.
Scheme 27: Mechanistic pathway for the NHC-catalyzed Stetter–Aldol–Michael reaction.
Scheme 28: Synthesis of 2-benzylidene-1-indanone derivatives 88a–d.
Scheme 29: Synthesis of 1-indanone derivatives 90a–i.
Scheme 30: Synthesis of 1-indanones 96 from o-bromobenzaldehydes 93 and alkynes 94.
Scheme 31: Synthesis of 3-hydroxy-1-indanones 99.
Scheme 32: Photochemical preparation of 1-indanones 103 from ketones 100.
Scheme 33: Synthesis of chiral 3-aryl-1-indanones 107.
Scheme 34: Photochemical isomerization of 2-methylbenzil 108.
Scheme 35: Synthesis of 2-hydroxy-1-indanones 111a–c.
Scheme 36: Synthesis of 1-indanone derivatives 113 and 114 from η6-1,2-dioxobenzocyclobutene complex 112.
Scheme 37: Synthesis of nakiterpiosin (117).
Scheme 38: Synthesis of 2-alkyl-1-indanones 120.
Scheme 39: Synthesis of fluorine-containing 1-indanone derivatives 123.
Scheme 40: Synthesis of 2-benzylidene and 2-benzyl-1-indanones 126, 127 from the chalcone 124.
Scheme 41: Synthesis of 2-bromo-6-methoxy-3-phenyl-1-indanone (130).
Scheme 42: Synthesis of combretastatin A-4-like indanones 132a–s.
Figure 3: Chemical structures of investigated dienones 133 and synthesized cyclic products 134–137.
Figure 4: Chemical structures of 1-indanones and their heteroatom analogues 138–142.
Scheme 43: Synthesis of 2-phosphorylated and 2-non-phosphorylated 1-indanones 147 and 148 from β-ketophosphona...
Scheme 44: Photochemical synthesis of 1-indanone derivatives 150, 153a, 153b.
Scheme 45: Synthesis of polysubstituted-1-indanones 155, 157.
Scheme 46: Synthesis of 1-indanones 159a–g from α-arylpropargyl alcohols 158 using RhCl(PPh3)3 as a catalyst.
Scheme 47: Synthesis of optically active 1-indanones 162 via the asymmetric Rh-catalyzed isomerization of race...
Scheme 48: Mechanism of the Rh-catalyzed isomerization of α-arylpropargyl alcohols 161 to 1-indanones 162.
Figure 5: Chemical structure of abicoviromycin (168) and its new benzo derivative 169.
Scheme 49: Synthesis of racemic benzoabicoviromycin 172.
Scheme 50: Synthesis of [14C]indene 176.
Scheme 51: Synthesis of indanone derivatives 178–180.
Scheme 52: Synthesis of racemic pterosin A 186.
Scheme 53: Synthesis of trans-2,3-disubstituted 1-indanones 189.
Scheme 54: Synthesis of 3-aryl-1-indanone derivatives 192.
Scheme 55: Synthesis of 1-indanone derivatives 194 from 3-(2-iodoaryl)propanonitriles 193.
Scheme 56: Synthesis of 1-indanones 200–204 by cyclization of aromatic nitriles.
Scheme 57: Synthesis of 1,1’-spirobi[indan-3,3’-dione] derivative 208.
Scheme 58: Total synthesis of atipamezole analogues 211.
Scheme 59: Synthesis of 3-[4-(1-piperidinoethoxy)phenyl]spiro[indene-1,1’-indan]-5,5’-diol hydrochloride 216.
Scheme 60: Synthesis of 3-arylindan-1-ones 219.
Scheme 61: Synthesis of 2-hydroxy-1-indanones 222.
Scheme 62: Synthesis of the 1-indanone 224 from the THP/MOM protected chalcone epoxide 223.
Scheme 63: Synthesis of 1-indanones 227 from γ,δ-epoxy ketones 226.
Scheme 64: Synthesis of 2-hydroxy-2-methylindanone (230).
Scheme 65: Synthesis of 1-indanone derivatives 234 from cyclopropanol derivatives 233.
Scheme 66: Synthesis of substituted 1-indanone derivatives 237.
Scheme 67: Synthesis of 7-methyl substituted 1-indanone 241 from 1,3-pentadiene (238) and 2-cyclopentenone (239...
Scheme 68: Synthesis of disubstituted 1-indanone 246 from the siloxydiene 244 and 2-cyclopentenone 239.
Scheme 69: Synthesis of 5-hydroxy-1-indanone (250) via the Diels–Alder reaction of 1,3-diene 248 with sulfoxid...
Scheme 70: Synthesis of halogenated 1-indanones 253a and 253b.
Scheme 71: Synthesis of 1-indanones 257 and 258 from 2-bromocyclopentenones 254.
Scheme 72: Synthesis of 1-indanone 261 from 2-bromo-4-acetoxy-2-cyclopenten-1-one (260) and 1,2-dihydro-4-viny...
Scheme 73: Synthesis of 1-indanone 265 from 1,2-dihydro-7-methoxy-4-vinylnaphthalene (262) and bromo-substitut...
Scheme 74: Synthesis of 1-indanone 268 from dihydro-3-vinylphenanthrene 266 and 4-acetoxy-2-cyclopenten-1-one (...
Scheme 75: Synthesis of 1-indanone 271 from phenylselenyl-substituted cyclopentenone 268.
Scheme 76: Synthesis of 1-indanone 272 from the trienone 270.
Scheme 77: Synthesis of the 1-indanone 276 from the aldehyde 273.
Scheme 78: Synthesis of 1-indanones 278 and 279.
Scheme 79: Synthesis of 1-indanone 285 from octa-1,7-diyne (282) and cyclopentenone 239.
Scheme 80: Synthesis of benz[f]indan-1-one (287) from cyclopentenone 239 and o-bis(dibromomethyl)benzene (286)....
Scheme 81: Synthesis of 3-methyl-substituted benz[f]indan-1-one 291 from o-bis(dibromomethyl)benzene (286) and...
Scheme 82: Synthesis of benz[f]indan-1-one (295) from the anthracene epidioxide 292.
Scheme 83: Synthesis of 1-indanone 299 from homophthalic anhydride 298 and cyclopentynone 297.
Scheme 84: Synthesis of cyano-substituted 1-indanone derivative 301 from 2-cyanomethylbenzaldehyde (300) and c...
Scheme 85: Synthesis of 1-indanone derivatives 303–305 from ketene dithioacetals 302.
Scheme 86: Synthesis of 1-indanones 309–316.
Scheme 87: Mechanism of the hexadehydro-Diels–Alder (HDDA) reaction.
Scheme 88: Synthesis of 1-indenone 318 and 1-indanones 320 and 321 from tetraynes 317 and 319.
Scheme 89: Synthesis of 1-indanone 320 from the triyn 319.
Scheme 90: Synthesis 1-indanone 328 from 2-methylfuran 324.
Scheme 91: Synthesis of 1-indanones 330 and 331 from furans 329.
Scheme 92: Synthesis of 1-indanone 333 from the cycloadduct 332.
Scheme 93: Synthesis of (S)-3-arylindan-1-ones 335.
Scheme 94: Synthesis of (R)-2-acetoxy-1-indanone 338.
Figure 6: Chemical structures of obtained cyclopenta[α]phenanthrenes 339.
Scheme 95: Synthesis of the benzoindanone 343 from arylacetaldehyde 340 with 1-trimethylsilyloxycyclopentene (...
Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones
- Antonia Di Mola,
- Maximilian Tiffner,
- Francesco Scorzelli,
- Laura Palombi,
- Rosanna Filosa,
- Paolo De Caprariis,
- Mario Waser and
- Antonio Massa
Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279
Graphical Abstract
Figure 1: Some chiral, bioactive isoindolinones.
Scheme 1: This work: 1) trans-1,2-cyclohexane diamine-based bifunctional ammonium salts 8 in the asymmetric s...
Scheme 2: Asymmetric cascade, crystallization and decarboxylation reaction.
Scheme 3: Proposed racemization pathways of isoindolinones 9 via retro-Michael process.
Scheme 4: Asymmetric synthesis of (S)-PD172938.
Scheme 5: Coupling of chiral acid 9 with p-tolylpiperazine and CuI arylation of chiral isoindolinones.
Selected synthetic strategies to cyclophanes
- Sambasivarao Kotha,
- Mukesh E. Shirbhate and
- Gopalkrushna T. Waghule
Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142
- muscopyridine starting with methyl acetoacetate (231). They treated 231 with 5-bromo-1-pentene to generate keto ester 232 (60%). The coupling of keto ester 232 with vinyl ketone 233 under phase-transfer catalysis conditions generated the new keto ester 234 (93%), which on treatment with lithium chloride at 120
Graphical Abstract
Figure 1: General representation of cyclophanes.
Figure 2: cyclophanes one or more with heteroatom.
Figure 3: Metathesis catalysts 12–17 and C–C coupling catalyst 18.
Figure 4: Natural products containing the cyclophane skeleton.
Figure 5: Turriane family of natural products.
Scheme 1: Synthesis of [3]ferrocenophanes through Mannich reaction. Reagents and conditions: (i) excess HNMe2...
Scheme 2: Synthesis of cyclophanes through Michael addition. Reagents and conditions: (i) xylylene dibromide,...
Scheme 3: Synthesis of normuscopyridine analogue 37 through an oxymercuration–oxidation strategy. Reagents an...
Scheme 4: Synthesis of tribenzocyclotriyne 39 through Castro–Stephens coupling reaction. Reagents and conditi...
Scheme 5: Synthesis of cyclophane 43 through Glaser–Eglinton coupling. Reagents and conditions: (i) 9,10-bis(...
Scheme 6: Synthesis of the macrocyclic C-glycosyl cyclophane through Glaser coupling. Reagents and conditions...
Scheme 7: Synthesis of cyclophane-containing complex 49 through Glaser–Eglinton coupling reaction. Reagents a...
Scheme 8: Synthesis of cyclophane 53 through Glaser–Eglinton coupling. Reagents and conditions: (i) K2CO3, ac...
Figure 6: Cyclophanes 54–56 that have been synthesized through Glaser–Eglinton coupling.
Figure 7: Synthesis of tetrasubstituted [2.2]paracyclophane 57 and chiral cyclophyne 58 through Eglinton coup...
Scheme 9: Synthesis of cyclophane through Glaser–Hay coupling reaction. Reagents and conditions: (i) CuCl2 (1...
Scheme 10: Synthesis of seco-C/D ring analogs of ergot alkaloids through intramolecular Heck reaction. Reagent...
Scheme 11: Synthesis of muscopyridine 73 via Kumada coupling. Reagents and conditions: (i) 72, THF, ether, 20 ...
Scheme 12: Synthesis of the cyclophane 79 via McMurry coupling. Reagents and conditions: (i) 75, decaline, ref...
Scheme 13: Synthesis of stilbenophane 81 via McMurry coupling. Reagents and conditions: (i) TiCl4, Zn, pyridin...
Scheme 14: Synthesis of stilbenophane 85 via McMurry coupling. Reagents and conditions: (i) NBS (2 equiv), ben...
Figure 8: List of cyclophanes prepared via McMurry coupling reaction as a key step.
Scheme 15: Synthesis of paracyclophane by cross coupling involving Pd(0) catalyst. Reagents and conditions: (i...
Scheme 16: Synthesis of the cyclophane 112 via the pinacol coupling and 113 by RCM. Reagents and conditions: (...
Scheme 17: Synthesis of cyclophane derivatives 122a–c via Sonogoshira coupling. Reagents and conditions: (i) C...
Scheme 18: Synthesis of cyclophane 130 via Suzuki–Miyaura reaction as a key step. Reagents and conditions: (i)...
Scheme 19: Synthesis of the mycocyclosin via Suzuki–Miyaura cross coupling. Reagents and conditions: (i) benzy...
Scheme 20: Synthesis of cyclophanes via Wurtz coupling reaction Reagents and conditions: (i) PhLi, Et2O, C6H6,...
Scheme 21: Synthesis of non-natural glycophanes using alkyne metathesis. Reagents and conditions: (i) G-I (12)...
Figure 9: Synthesis of cyclophanes via ring-closing alkyne metathesis.
Scheme 22: Synthesis of crownophanes by cross-enyne metathesis. Reagents and conditions: (i) G-II (13), 5 mol ...
Scheme 23: Synthesis of (−)-cylindrocyclophanes A (156) and (−)-cylindrocyclophanes F (155). Reagents and cond...
Scheme 24: Synthesis of cyclophane 159 derivatives via SM cross-coupling and RCM. Reagents and conditions: (i)...
Scheme 25: Sexithiophene synthesis via cross metathesis. Reagents and conditions: (i) 161, Pd(PPh3)4, K2CO3, T...
Scheme 26: Synthesis of pyrrole-based cyclophane using enyne metathesis. Reagents and conditions: (i) Se, chlo...
Scheme 27: Synthesis of macrocyclic derivatives by RCM. Reagents and conditions: (i) G-I/G-II, CH2Cl2, 0.005 M...
Scheme 28: Synthesis of enantiopure β-lactam-based dienyl bis(dihydrofuran) 179. Reagents and conditions: (i) ...
Scheme 29: Synthesis of a [1.1.6]metaparacyclophane derivative 183 via SM cross coupling. Reagents and conditi...
Scheme 30: Synthesis of a [1.1.6]metaparacyclophane derivative 190 via SM cross coupling. Reagents and conditi...
Scheme 31: Template-promoted synthesis of cyclophanes involving RCM. Reagents and conditions: (i) acenaphthene...
Scheme 32: Synthesis of [3.4]cyclophane derivatives 200 via SM cross coupling and RCM. Reagents and conditions...
Figure 10: Examples for cyclophanes synthesized by RCM.
Scheme 33: Synthesis of the longithorone C framework assisted by fluorinated auxiliaries. Reagents and conditi...
Scheme 34: Synthesis of the longithorone framework via RCM. Reagents and conditions: (i) 213, NaH, THF, rt, 10...
Scheme 35: Synthesis of floresolide B via RCM as a key step. Reagents and conditions: (i) G-II (13, 0.1 equiv)...
Scheme 36: Synthesis of normuscopyridine (223) by the RCM strategy. Reagents and condition: (i) Mg, THF, hexen...
Scheme 37: Synthesis of muscopyridine (73) via RCM. Reagents and conditions: (i) 225, NaH, THF, 0 °C to rt, 1....
Scheme 38: Synthesis of muscopyridine (73) via RCM strategy. Reagents and conditions: (i) NaH, n-BuLi, 5-bromo...
Scheme 39: Synthesis of pyridinophane derivatives 223 and 245. Reagents and conditions: (i) PhSO2Na, TBAB, CH3...
Scheme 40: Synthesis of metacyclophane derivatives 251 and 253. Reagents and conditions: (i) 240, NaH, THF, rt...
Scheme 41: Synthesis of normuscopyridine and its higher analogues. Reagents and conditions: (i) alkenyl bromid...
Scheme 42: Synthesis of fluorinated ferrocenophane 263 via a [2 + 2] cycloaddition. Reagents and conditions: (...
Scheme 43: Synthesis of [2.n]metacyclophanes 270 via a [2 + 2] cycloaddition. Reagents and conditions: (i) Ac2...
Scheme 44: Synthesis of metacyclophane 273 by a [2 + 2 + 2] co-trimerization. Reagents and conditions: (i) [Rh...
Scheme 45: Synthesis of paracyclophane 276 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditions: ...
Scheme 46: Synthesis of cyclophane 278 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditions: (i) ...
Scheme 47: Synthesis of cyclophane 280 via a [2 + 2 + 2] cycloaddition. Reagents and conditions: (i) [(Rh(cod)(...
Scheme 48: Synthesis of taxane framework by a [2 + 2 + 2] cycloaddition. Reagents and conditions: (i) Cp(CO)2 ...
Scheme 49: Synthesis of cyclophane 284 and 285 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditio...
Scheme 50: Synthesis of pyridinophanes 293a,b and 294a,b via a [2 + 2 + 2] cycloaddition. Reagents and conditi...
Scheme 51: Synthesis of pyridinophanes 296 and 297 via a [2 + 2 + 2] cycloaddition. Reagents and conditions: (...
Scheme 52: Synthesis of triazolophane by a 1,3-dipolar cycloaddition. Reagents and conditions: (i) propargyl b...
Scheme 53: Synthesis of glycotriazolophane 309 by a click reaction. Reagents and conditions: (i) LiOH, H2O, Me...
Figure 11: Cyclophanes 310 and 311 prepared via click chemistry.
Scheme 54: Synthesis of cyclophane via the Dötz benzannulation. Reagents and conditions: (i) THF, 100 °C, 12 h...
Scheme 55: Synthesis of [6,6]metacyclophane by a Dötz benzannulation. Reagents and conditions: (i) THF, 100 °C...
Scheme 56: Synthesis of cyclophanes by a Dötz benzannulation. Reagents and conditions: (i) THF, 65 °C, 3 h; (i...
Scheme 57: Synthesis of muscopyridine (73) via an intramolecular DA reaction of ketene. Reagents and condition...
Scheme 58: Synthesis of bis[10]paracyclophane 336 via Diels–Alder reaction. Reagents and conditions: (i) DMAD,...
Scheme 59: Synthesis of [8]paracyclophane via DA reaction. Reagents and conditions: (i) maleic anhydride, 3–5 ...
Scheme 60: Biomimetic synthesis of (−)-longithorone A. Reagents and conditions: (i) Me2AlCl, CH2Cl2, −20 °C, 7...
Scheme 61: Synthesis of sporolide B (349) via a [4 + 2] cycloaddition reaction. Reagents and conditions: (i) P...
Scheme 62: Synthesis of the framework of (+)-cavicularin (352) via a [4 + 2] cycloaddition. Reagents and condi...
Scheme 63: Synthesis of oxazole-containing cyclophane 354 via Beckmann rearrangement. Reagents and conditions:...
Scheme 64: Synthesis of cyclophanes 360a–c via benzidine rearrangement. Reagents and conditions: (i) 356a–d, K2...
Scheme 65: Synthesis of cyclophanes 365a–c via benzidine rearrangement. Reagents and conditions: (i) BocNHNH2,...
Scheme 66: Synthesis of metacyclophane 367 via Ciamician–Dennstedt rearrangement. Reagents and conditions: (i)...
Scheme 67: Synthesis of cyclophane by tandem Claisen rearrangement and RCM as key steps. Reagents and conditio...
Scheme 68: Synthesis of cyclophane derivative 380. Reagents and conditions: (i) K2CO3, CH3CN, allyl bromide, r...
Scheme 69: Synthesis of metacyclophane via Cope rearrangement. Reagents and conditions: (i) MeOH, NaBH4, rt, 1...
Scheme 70: Synthesis of cyclopropanophane via Favorskii rearrangement. Reagents and conditions: (i) Br2, CH2Cl2...
Scheme 71: Cyclophane 389 synthesis via photo-Fries rearrangement. Reagents and conditions: (i) DMAP, EDCl/CHCl...
Scheme 72: Synthesis of normuscopyridine (223) via Schmidt rearrangement. Reagents and conditions: (i) ethyl s...
Scheme 73: Synthesis of crownophanes by tandem Claisen rearrangement. Reagents and conditions: (i) diamine, Et3...
Scheme 74: Attempted synthesis of cyclophanes via tandem Claisen rearrangement and RCM. Reagents and condition...
Scheme 75: Synthesis of muscopyridine via alkylation with 2,6-dimethylpyridine anion. Reagents and conditions:...
Scheme 76: Synthesis of cyclophane via Friedel–Craft acylation. Reagents and conditions: (i) CS2, AlCl3, 7 d, ...
Scheme 77: Pyridinophane 418 synthesis via Friedel–Craft acylation. Reagents and conditions: (i) 416, AlCl3, CH...
Scheme 78: Cyclophane synthesis involving the Kotha–Schölkopf reagent 421. Reagents and conditions: (i) NBS, A...
Scheme 79: Cyclophane synthesis involving the Kotha–Schölkopf reagent 421. Reagents and conditions: (i) BEMP, ...
Scheme 80: Cyclophane synthesis by coupling with TosMIC. Reagents and conditions: (i) (a) ClCH2OCH3, TiCl4, CS2...
Scheme 81: Synthesis of diaza[32]cyclophanes and triaza[33]cyclophanes. Reagents and conditions: (i) DMF, NaH,...
Scheme 82: Synthesis of cyclophane 439 via acyloin condensation. Reagents and conditions: (i) Na, xylene, 75%;...
Scheme 83: Synthesis of multibridged binuclear cyclophane 442 by aldol condensation. Reagents and conditions: ...
Scheme 84: Synthesis of various macrolactones. Reagents and conditions: (i) iPr2EtN, DMF, 77–83%; (ii) TBDMSCl...
Scheme 85: Synthesis of muscone and muscopyridine via Yamaguchi esterification. Reagents and conditions: (i) 4...
Scheme 86: Synthesis of [5]metacyclophane via a double elimination reaction. Reagents and conditions: (i) LiBr...
Figure 12: Cyclophanes 466–472 synthesized via Hofmann elimination.
Scheme 87: Synthesis of cryptophane via Baylis–Hillman reaction. Reagents and conditions: (i) methyl acrylate,...
Scheme 88: Synthesis of cyclophane 479 via double Chichibabin reaction. Reagents and conditions: (i) excess 478...
Scheme 89: Synthesis of cyclophane 483 via double Chichibabin reaction. Reagents and conditions: (i) 481, OH−;...
Scheme 90: Synthesis of cyclopeptide via an intramolecular SNAr reaction. Reagents and conditions: (i) TBAF, T...
Scheme 91: Synthesis of muscopyridine (73) via C-zip ring enlargement reaction. Reagents and conditions: (i) H...
Figure 13: Mechanism of the formation of compound 494.
Scheme 92: Synthesis of indolophanetetraynes 501a,b using the Nicholas reaction as a key step. Reagents and co...
Scheme 93: Synthesis of cyclophane via radical cyclization. Reagents and conditions: (i) cyclododecanone, phen...
Scheme 94: Synthesis of (−)-cylindrocyclophanes A (156) and (−)-cylindrocyclophanes F (155). Reagents and cond...
Scheme 95: Cyclophane synthesis via Wittig reaction. Reagents and conditions: (i) LiOEt (2.1 equiv), THF, −78 ...
Figure 14: Representative examples of cyclophanes synthesized via Wittig reaction.
Scheme 96: Synthesis of the [6]paracyclophane via isomerization of Dewar benzene. Reagents and conditions: (i)...
First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine
- Paweł Borowiecki,
- Daniel Paprocki and
- Maciej Dranka
Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322
- -product formation, we thereby performed the reaction under phase transfer catalysis (PTC) conditions. The results of this experiments have shown that independently from the type of the used reaction media (toluene, CH2Cl2, diethyl ether), bases (50% NaOH or 60% KOH), and the applied PTC-catalysts
Graphical Abstract
Scheme 1: Chemoenzymatic synthesis of enantioenriched enantiomers of promethazine 9 and ethopropazine 10. Rea...
Figure 1: Dependence of optical purities (% ee) of (R)-(−)-6a (red curve, ■) and (S)-(+)-5 (blue curve, ▲) on...
Scheme 2: Assignment of the stereochemistry of enantiopure alcohol (+)-5 resulting from derivatization with (R...
Figure 2: Description of substituents for determination of the absolute configuration of (+)-5 and ΔδRS value...
Figure 3: 1H NMR (CDCl3, 400 MHz) spectra of the (R)-MPA 11 (red colored line) and (S)-MPA and 12 (blue color...
Figure 4: An ORTEP plot of (S)-(+)-1-(10H-phenothiazin-10-yl)propan-2-ol (S)-(+)-5. The following crystal str...
Scheme 3: Amination of optically active bromo derivatives (R)-(+)-8 or (S)-(−)-8 in toluene.
Scheme 4: Amination of optically active bromo derivatives (R)-(+)-8 or (S)-(−)-8 in methanol.
Scheme 5: The proposed reaction mechanism for amination of optically active (S)-(−)-8 in methanol.
Atherton–Todd reaction: mechanism, scope and applications
- Stéphanie S. Le Corre,
- Mathieu Berchel,
- Hélène Couthon-Gourvès,
- Jean-Pierre Haelters and
- Paul-Alain Jaffrès
Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117
- or secondary amines can be also used when they simultaneously act as a nucleophile and a base. In that case, two equivalents of amine must be added (Scheme 11). The use of NaOH as a base was also reported (exemplified in Scheme 10) in a protocol involving phase-transfer catalysis. Initially, the
- reaction proceeded in CCl4 in the presence of triethylamine and produced phosphoramidates in 60–82% yield. Unsubstituted hydrazine can also be used as a nucleophile in the AT reaction [45][46][47]. The best synthetic conditions employed phase-transfer catalysis [48]. Accordingly, CCl4 was used as a solvent
- yields (77–88%). Interestingly, the same authors reported that pseudo-halide phosphate can also be obtained by using phase-transfer catalysis [68]. Accordingly, NaX (X = N3, CN or NCS) reacts with dialkyl phosphate in water–organic solvent mixtures under phase-transfer catalysis. The catalyst was either
Graphical Abstract
Scheme 1: Pioneer works of Atherton, Openshaw and Todd reporting on the synthesis of phosphoramidate starting...
Scheme 2: Mechanisms 1 (i) and 2 (ii) suggested by Atherton and Todd in 1945; adapted from [1].
Scheme 3: Two reaction pathways (i and ii) to produce chlorophosphate 2. Charge-transfer complex observed whe...
Scheme 4: Mechanism of the Atherton–Todd reaction with dimethylphosphite according to Roundhill et al. (adapt...
Scheme 5: Synthesis of dialkyl phosphate from dialkyl phosphite (i) and identification of chloro- and bromoph...
Scheme 6: Synthesis of chiral phosphoramidate with trichloromethylphosphonate as the suggested intermediate (...
Scheme 7: Selection of results that address the question of the stereochemistry of the AT reaction (adapted f...
Scheme 8: Synthesis of phenoxy spirophosphorane by the AT reaction (adapted from [34]).
Scheme 9: Suggested mechanism of the Atherton–Todd reaction, (i) and (ii) formation of chlorophosphate with a...
Scheme 10: AT reaction in biphasic conditions (adapted from [38]).
Scheme 11: AT reaction with iodoform as halide source (adapted from [37]).
Scheme 12: AT reaction with phenol at low temperature in the presence of DMAP (adapted from [40]).
Scheme 13: Synthesis of a triphosphate by the AT reaction starting with the preparation of chlorophosphate (ad...
Scheme 14: AT reaction with sulfonamide (adapted from [42]).
Scheme 15: Synthesis of a styrylphosphoramidate starting from the corresponding aniline (adapted from [43]).
Scheme 16: Use of hydrazine as nucleophile in AT reactions (adapted from [48]).
Scheme 17: AT reaction with phenol as a nucleophilic species; synthesis of dioleyl phosphate-substituted couma...
Scheme 18: Synthesis of β-alkynyl-enolphosphate from allenylketone with AT reaction (adapted from [58]).
Scheme 19: Synthesis of pseudohalide phosphate by using AT reaction (adapted from [67]).
Scheme 20: AT reaction with hydrospirophosphorane with insertion of CO2 in the product (adapted from [69]).
Scheme 21: AT reaction with diaryl phosphite (adapted from [70]).
Scheme 22: AT reaction with O-alkyl phosphonite (adapted from [71]).
Scheme 23: Use of phosphinous acid in AT reactions (adapted from [72]).
Scheme 24: AT reaction with secondary phosphinethiooxide (adapted from [76]).
Scheme 25: Use of H-phosphonothioate in the AT reaction (adapted from [78]).
Scheme 26: AT-like reaction with CuI as catalyst and without halide source (adapted from [80]).
Scheme 27: Reduction of phenols after activation as phosphate derivatives (adapted from [81] i ; [82], ii; and [83], iii).
Scheme 28: Synthesis of medium and large-sized nitrogen-containing heterocycles (adapted from [85]).
Scheme 29: Synthesis of arylstannane from aryl phosphate prepared by an AT reaction (adapted from [86]).
Scheme 30: Synthesis and use of aryl dialkyl phosphate for the synthesis of biaryl derivatives (adapted from [89])....
Scheme 31: Synthesis of aryl dialkyl phosphate by an AT reaction from phenol and subsequent rearrangement yiel...
Scheme 32: Selected chiral phosphoramidates used as organocatalyst; i) chiral phosphoramidate used in the pion...
Scheme 33: Determination of ee of H-phosphinate by the application of the AT reaction with a chiral amine (ada...
Scheme 34: Chemical structure of selected flame retardants synthesized by AT reactions; (BDE: polybrominated d...
Scheme 35: Transformation of DOPO (i) and synthesis of polyphosphonate (ii) by the AT reaction (adapted from [117] ...
Scheme 36: Synthesis of lipophosphite (bisoleyl phosphite) and cationic lipophosphoramidate with an AT reactio...
Scheme 37: Use of AT reactions to produce cationic lipids characterized by a trimethylphosphonium, trimethylar...
Scheme 38: Cationic lipid synthesized by the AT reaction illustrating the variation of the structure of the li...
Scheme 39: Helper lipids for nucleic acid delivery synthesized with the AT reaction (adapted from [130]).
Scheme 40: AT reaction used to produce red/ox-sensitive cationic lipids (adapted from [135]).
Scheme 41: Alkyne and azide-functionalized phosphoramidate synthesized by AT reactions,(i); illustration of so...
Scheme 42: Cationic lipids exhibiting bactericidal action – arrows indicate the bond formed by the AT reaction...
Scheme 43: β-Cyclodextrin-based lipophosphoramidates (adapted from [138]).
Scheme 44: Polyphosphate functionalized by an AT reaction (adapted from [139]).
Scheme 45: Synthesis of zwitterionic phosphocholine-bound chitosan (adapted from [142]).
Scheme 46: Synthesis of AZT-based prodrug via an AT reaction (adapted from [143]).
The chemistry of bisallenes
- Henning Hopf and
- Georgios Markopoulos
Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225
Graphical Abstract
Figure 1: Loschmidt’s structure proposal for benzene (1) (Scheme 181 from [3]) and the corresponding modern stru...
Figure 2: The first isolated bisallenes.
Figure 3: Carbon skeletons of selected bisallenes discussed in this review.
Scheme 1: The preparation of 1,2,4,5-hexatetraene (2).
Scheme 2: The preparation of a conjugated bisallene by the DMS-protocol.
Scheme 3: Preparation of the 3-deuterio- and 3,4-dideuterio derivatives of 24.
Scheme 4: A versatile method to prepare alkylated conjugated bisallenes and other allenes.
Scheme 5: A preparation of 3,4-dimethyl-1,2,4,5-hexatetraene (38).
Scheme 6: A (C6 + 0)-approach to 1,2,4,5-hexatetraene (2).
Scheme 7: The preparation of a fully alkylated bisallenes from a 2,4-hexadiyne-1,6-diol diacetate.
Scheme 8: The preparation of the first phenyl-substituted conjugated bisallenes 3 and 4.
Scheme 9: Selective hydrogenation of [5]cumulenes to conjugated bisallenes: another (C6 + 0)-route.
Scheme 10: Aryl-substituted conjugated bisallenes by a (C3 + C3)-approach.
Scheme 11: Hexaphenyl-1,2,4,5-hexatetraene (59) by a (C3 + C3)-approach.
Scheme 12: An allenation route to conjugated bisallenes.
Scheme 13: The preparation of 3,4-difunctionalized conjugated bisallenes.
Scheme 14: Problems during the preparation of sulfur-substituted conjugated bisallenes.
Scheme 15: The preparation of 3,4-dibromo bisallenes.
Scheme 16: Generation of allenolates by an oxy-Cope rearrangement.
Scheme 17: A linear trimerization of alkynes to conjugated bisallenes: a (C2 + C2 + C2)-protocol.
Scheme 18: Preparation of a TMS-substituted conjugated bisallene by a C3-dimerization route.
Scheme 19: A bis(trimethylsilyl)bisallene by a C3-coupling protocol.
Scheme 20: The rearrangement of highly substituted benzene derivatives into their conjugated bisallenic isomer...
Scheme 21: From fully substituted benzene derivatives to fully substituted bisallenes.
Scheme 22: From a bicyclopropenyl to a conjugated bisallene derivative.
Scheme 23: The conversion of a bismethylenecyclobutene into a conjugated bisallene.
Scheme 24: The preparation of monofunctionalized bisallenes.
Scheme 25: Preparation of bisallene diols and their cyclization to dihydrofurans.
Scheme 26: A 3,4-difunctionalized conjugated bisallene by a C3-coupling process.
Scheme 27: Preparation of a bisallenic diketone by a coupling reaction.
Scheme 28: Sulfur and selenium-substituted bisallenes by a [2.3]sigmatropic rearrangement.
Scheme 29: The biallenylation of azetidinones.
Scheme 30: The preparation of a fully ferrocenylated conjugated bisallene.
Scheme 31: The first isomerization of a 1,5-hexadiyne to a 1,2,4,5-hexatetraene.
Scheme 32: The preparation of alkynyl-substituted bisallenes by a C3-dimerization protocol.
Scheme 33: Preparation of another completely ferrocenylated bisallene.
Scheme 34: The cyclization of 1,5-hexadiyne (129) to 3,4-bismethylenecyclobutene (130) via 1,2,4,5-hexatetraen...
Scheme 35: Stereochemistry of the thermal cyclization of bisallenes to bismethylenecyclobutenes.
Scheme 36: Bisallene→bismethylenecyclobutene ring closures in the solid state.
Scheme 37: A bisallene cyclization/dimerization reaction.
Scheme 38: A selection of Diels–Alder additions of 1,2,4,5-hexatetraene with various double-bond dienophiles.
Scheme 39: The stereochemistry of the [2 + 4] cycloaddition to conjugated bisallenes.
Scheme 40: Preparation of azetidinone derivatives from conjugated bisallenes.
Scheme 41: Cycloaddition of heterodienophiles to a conjugated bisallene.
Scheme 42: Addition of triple-bond dienophiles to conjugated bisallenes.
Scheme 43: Sulfur dioxide addition to conjugated bisallenes.
Scheme 44: The addition of a germylene to a conjugated bisallene.
Scheme 45: Trapping of conjugated bisallenes with phosphinidenes.
Scheme 46: The cyclopropanantion of 1,2,4,5-hexatetraene (2).
Scheme 47: Photochemical reactions involving conjugated bisallenes.
Scheme 48: Base-catalyzed isomerizations of conjugated bisallenes.
Scheme 49: Ionic additions to a conjugated bisallene.
Scheme 50: Oxidation reactions of a conjugated bisallene.
Scheme 51: The mechanism of oxidation of the bisallene 24.
Scheme 52: CuCl-catalyzed cyclization of 1,2,4,5-hexatetraene (2).
Scheme 53: The conversion of conjugated bisallenes into cyclopentenones.
Scheme 54: Oligomerization of a conjugated bisallene by nickel catalysts.
Scheme 55: Generation of 1,2,5,6-heptatetraene (229) as a reaction intermediate.
Scheme 56: The preparation of a stable derivative of 1,2,5,6-heptatetraene.
Scheme 57: A bisallene with a carbonyl group as a spacer element.
Scheme 58: The first preparation of 1,2,6,7-octatetraene (242).
Scheme 59: Preparation of 1,2,6,7-octatetraenes by (C4 + C4)-coupling of enynes.
Scheme 60: Preparation of 1,2,6,7-octatetraenes by (C4 + C4)-coupling of homoallenyl bromides.
Scheme 61: Preparation of 1,2,6,7-octatetraenes by alkylation of propargylic substrates.
Scheme 62: Preparation of two highly functionalized 1,2,6,7-octatetraenes.
Scheme 63: Preparation of several higher α,ω-bisallenes.
Scheme 64: Preparation of different alkyl derivatives of α,ω-bisallenes.
Scheme 65: The preparation of functionalized 1,2,7,8-nonatetraene derivatives.
Scheme 66: Preparation of functionalized α,ω-bisallenes.
Scheme 67: The preparation of an α,ω-bisallene by direct homologation of an α,ω-bisalkyne.
Scheme 68: The gas-phase pyrolysis of 4,4-dimethyl-1,2,5,6-heptatetraene (237).
Scheme 69: Gas-phase pyrolysis of 1,2,6,7-octatetraene (242).
Scheme 70: The cyclopropanation of 1,2,6,7-octatetraene (242).
Scheme 71: Intramolecular cyclization of 1,2,6,7-octatetraene derivatives.
Scheme 72: The gas-phase pyrolysis of 1,2,7,8-nonatetraene (265) and 1,2,8,9-decatetraene (266).
Scheme 73: Rh-catalyzed cyclization of a functionalized 1,2,7,8-nonatetraene.
Scheme 74: A triple cyclization involving two different allenic substrates.
Scheme 75: Bicyclization of keto derivatives of 1,2,7,8-nonatetraene.
Scheme 76: The preparation of complex organic compounds from functionalized bisallenes.
Scheme 77: Cycloisomerization of an α,ω-bisallene containing a C9 tether.
Scheme 78: Organoborane polymers from α,ω-bisallenes.
Scheme 79: Preparation of trans- (337) and cis-1,2,4,6,7-octapentaene (341).
Scheme 80: The preparation of 4-methylene-1,2,5,6-heptatetraene (349).
Scheme 81: The preparation of acetylenic bisallenes.
Scheme 82: The preparation of derivatives of hydrocarbon 351.
Scheme 83: The construction of macrocyclic alleno-acetylenes.
Scheme 84: Preparation and reactions of 4,5-bismethylene-1,2,6,7-octatetraene (365).
Scheme 85: Preparation of 1,2-bis(propadienyl)benzene (370).
Scheme 86: The preparation of 1,4-bis(propadienyl)benzene (376).
Scheme 87: The preparation of aromatic and heteroaromatic bisallenes by metal-mediated coupling reactions.
Scheme 88: Double cyclization of an aromatic bisallene.
Scheme 89: Preparation of an allenic [15]paracyclophane by a ring-closing metathesis reaction of an aromatic α...
Scheme 90: Preparation of a macrocyclic ring system containing 1,4-bis(propadienyl)benzene units.
Scheme 91: Preparation of copolymers from 1,4-bis(propadienyl)benzene (376).
Scheme 92: A boration/copolymerization sequence of an aromatic bisallene and an aromatic bisacetylene.
Scheme 93: Formation of a layered aromatic bisallene.
Figure 4: The first members of the semicyclic bisallene series.
Scheme 94: Preparation of the first bis(vinylidene)cyclobutane derivative.
Scheme 95: Dimerization of strain-activated cumulenes to bis(vinylidene)cyclobutanes.
Scheme 96: Photodimerization of two fully substituted butatrienes in the solid state.
Scheme 97: Preparation of the two parent bis(vinylidene)cyclobutanes.
Scheme 98: The preparation of 1,3-bis(vinylidene)cyclopentane and its thermal isomerization.
Scheme 99: The preparation of the isomeric bis(vinylidene)cyclohexanes.
Scheme 100: Bi- and tricyclic conjugated bisallenes.
Scheme 101: A selection of polycyclic bisallenes.
Scheme 102: The first endocyclic bisallenes.
Figure 5: The stereochemistry of 1,2,6,7-cyclodecatetraene.
Scheme 103: The preparation of several endocyclic bisallenes.
Scheme 104: Synthesis of diastereomeric derivatives of 1,2,6,7-cyclodecatetraene.
Scheme 105: Preparation of a derivative of 1,2,8,9-cyclotetradecatetraene.
Scheme 106: The preparation of keto derivatives of cyclic bisallenes.
Scheme 107: The preparation of cyclic biscumulenic ring systems.
Scheme 108: Cyclic bisallenes in natural- and non-natural-product chemistry.
Scheme 109: The preparation of iron carbonyl complexes from cyclic bisallenes.
Figure 6: A selection of unknown exocyclic bisallenes that should have interesting chemical properties.
Scheme 110: The thermal isomerization of 1,2-diethynylcyclopropanes and -cyclobutanes.
Scheme 111: Intermediate generation of a cyclooctapentaene.
Scheme 112: Attempted preparation of a cyclodecahexaene.
Scheme 113: The thermal isomerization of 1,5,9-cyclododecatriyne (511) into [6]radialene (514).
Scheme 114: An isomerization involving a diketone derived from a conjugated bisallene.
Scheme 115: Typical reaction modes of heteroorganic bisallenes.
Scheme 116: Generation and thermal behavior of acyclic hetero-organic bisallenes.
Scheme 117: Generation of bis(propadienyl)thioether.
Scheme 118: The preparation of a bisallenic sulfone and its thermal isomerization.
Scheme 119: Bromination of the bisallenic sulfone 535.
Scheme 120: Metalation/hydrolysis of the bisallenic sulfone 535.
Scheme 121: Aromatic compounds from hetero bisallenes.
Scheme 122: Isomerization/cyclization of bispropargylic ethers.
Scheme 123: The preparation of novel aromatic systems by base-catalyzed isomerization of bispropargyl ethers.
Scheme 124: The isomerization of bisacetylenic thioethers to bicyclic thiophenes.
Scheme 125: Aromatization of macrocyclic bispropargylic sulfides.
Scheme 126: Preparation of ansa-compounds from macrocyclic bispropargyl thioethers.
Scheme 127: Alternate route for cyclization of a heterorganic bisallene.
Scheme 128: Multiple isomerization/cyclization of “double” bispropargylic thioethers.
Scheme 129: Preparation of a bisallenyl disulfide and its subsequent bicyclization.
Scheme 130: Thermal cyclization of a bisallenyl thiosulfonate.
Scheme 131: Some reactions of heteroorganic bisallenes with two sulfur atoms.
Scheme 132: Further methods for the preparation of heteroorganic bisallenes.
Scheme 133: Cyclization reactions of heteroorganic bisallenes.
Scheme 134: Thermal cycloadditions of bisallenic tertiary amines.
Scheme 135: Cyclization of a bisallenic tertiary amine in the presence of a transition-metal catalyst.
Scheme 136: A Pauson–Khand reaction of a bisallenic ether.
Scheme 137: Formation of a 2:1adduct from two allenic substrates.
Scheme 138: A ring-forming silastannylation of a bisallenic tertiary amine.
Scheme 139: A three-component cyclization involving a heterorganic bisallene.
Scheme 140: Atom-economic construction of a complex organic framework from a heterorganic α,ω-bisallene.
Acceptor-influenced and donor-tuned base-promoted glycosylation
- Stephan Boettcher,
- Martin Matwiejuk and
- Joachim Thiem
Beilstein J. Org. Chem. 2012, 8, 413–420, doi:10.3762/bjoc.8.46
- glucopyranosyl acceptors 1–4 started with benzylidenation [4] of compound 10 and 11, respectively (Scheme 1). As the next step, monobenzylation of 12 and 13 by phase-transfer catalysis [5] afforded derivatives 14–17. Subsequent cleavage of the benzylidene protecting group [4] gave the target compounds 1–4 in
Graphical Abstract
Figure 1: Monobenzylated methyl α- and β-D-gluco- and galactopyranoside acceptors 1–6.
Figure 2: Benzylated glycopyranosyl halide donors 7–9.
Scheme 1: Synthesis of monobenzylated glucopyranosyl acceptors 1–4. Reagents and conditions: (a) Benzaldehyde...
Scheme 2: Synthesis of 3-O-monobenzylated gluco- und galactopyranosyl acceptors 5 and 6. Reagents and conditi...
Scheme 3: Synthesis of 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl chloride (8) and 2,3,4,6-tetra-O-benzyl-α-...
The preparation of 3-substituted-1,5-dibromopentanes as precursors to heteracyclohexanes
- Bryan Ringstrand,
- Martin Oltmanns,
- Jeffrey A. Batt,
- Aleksandra Jankowiak,
- Richard P. Denicola and
- Piotr Kaszynski
Beilstein J. Org. Chem. 2011, 7, 386–393, doi:10.3762/bjoc.7.49
- ], while the latter from p-toluenesulfonyl chloride in the presence of a base such as pyridine [13][17][18][19][20]. Dibromides I can also be obtained by the ring-opening of tetrahydropyrans VIII under the same conditions employed for the diols VII [2][12][21][22], or via phase-transfer catalysis
Graphical Abstract
Figure 1: Methods for synthesis of dibromides I and their use for preparation of 6-membered heterocycles.
Scheme 1: General methods for preparation of diols VII.
Scheme 2: General methods for preparation of tetrahydropyrans VIII.
Figure 2: Structures of 1,5-dibromomopentanes 1a–1d.
Scheme 3: Preparation of dibromides 1.
Scheme 4: Preparation of diol 2a.
Scheme 5: Preparation of diol 2b.
Scheme 6: Preparation of tetrahydropyrans 3a–3c.
Scheme 7: Preparation of tetrahydropyran 3d.
Scheme 8: Preparation of methylenetetrahydropyrans 6.
Scheme 9: Preparation of bromides 8 and 10.
Scheme 10: Preparation of sulfonium derivatives 11.
Synthesis of cationic dibenzosemibullvalene-based phase-transfer catalysts by di-π-methane rearrangements of pyrrolinium-annelated dibenzobarrelene derivatives
- Heiko Ihmels and
- Jia Luo
Beilstein J. Org. Chem. 2011, 7, 119–126, doi:10.3762/bjoc.7.17
- pyrrolidinium-annelated dibenzosemibullvalene may act as phase-transfer catalyst in alkylation reactions. Keywords: di-π-methane rearrangement; dibenzobarrelenes; dibenzosemibullvalenes; phase-transfer catalysis; photochemistry; polycylic compounds; Introduction The di-π-methane (DPM) rearrangement is among
Graphical Abstract
Scheme 1: Photorearrangements of dibenzobarrelene (DBB).
Figure 1: General structure of pyrrolidinium-annelated dibenzosemibullvalenes (pyDBS).
Scheme 2: Synthesis of dibenzobarrelene derivatives 2a–g.
Scheme 3: Di-π-methane rearrangements of dibenzobarrelene derivatives 2a–f (counter ions omitted for clarity)....
Scheme 4: Di-π-methane rearrangement of dibenzobarrelene derivative 2g.
Scheme 5: Synthesis and solid-state photoreactivity of the sulfonate salt 2b-4.
Scheme 6: Phase-transfer catalyzed alkylation reactions (see Table 1 for details).
Synthesis of the fluorescent amino acid rac-(7-hydroxycoumarin-4-yl)ethylglycine
- Manfred Braun and
- Torsten Dittrich
Beilstein J. Org. Chem. 2010, 6, No. 69, doi:10.3762/bjoc.6.69
- transfer catalysis [16]. However, only an insignificant enantiomeric excess was observed in the alkylation product 7 when a representative protocol was applied [17]. Finally, the three protecting groups, the tert-butyl ester, the imine, and the silyl ether, were removed in a single step by hydrolysis with
- imine 7 in 67% yield. Under the aprotic conditions of the alkylation protocol, the silyl protecting group turned out to be stable, a fact which facilitated the purification of the imine 7. It is an obvious idea to apply the established protocols for the enantioselective alkylation of ester 6 under phase
Graphical Abstract
Figure 1: Fluorescent amino acid (7-hydroxycoumarin-4-yl)ethylglycine (1).
Scheme 1: Synthetic route to racemic amino acid 1·HCl. Reagents and conditions: a) BH3·SMe2, THF, 0 °C to r. ...
Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective
- Norio Shibata,
- Andrej Matsnev and
- Dominique Cahard
Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65
- -nitro esters. In particular, reagent 37 was found to be an effective trifluoromethylating agent. Under phase-transfer catalysis the β-keto esters derived from indanone, tetralone and pentanone in the presence of 37 gave the corresponding trifluoromethylated product in 42–67% yields. The new reagents
Graphical Abstract
Scheme 1: Preparation of the first electrophilic trifluoromethylating reagent and its reaction with a thiophe...
Scheme 2: Synthetic routes to S-CF3 and Se-CF3 dibenzochalcogenium salts.
Scheme 3: Synthesis of (trifluoromethyl)dibenzotellurophenium salts.
Scheme 4: Nitration of (trifluoromethyl)dibenzochalcogenium salts.
Scheme 5: Synthesis of a sulphonium salt with a bridged oxygen.
Scheme 6: Reactivity of (trifluoromethyl)dibenzochalcogenium salts.
Scheme 7: Pd(II)-Catalyzed ortho-trifluoromethylation of heterocycle-substituted arenes by Umemoto’s reagents....
Scheme 8: Mild electrophilic trifluoromethylation of β-ketoesters and silyl enol ethers.
Scheme 9: Enantioselective electrophilic trifluoromethylation of β-ketoesters.
Scheme 10: Preparation of water-soluble S-(trifluoromethyl)dibenzothiophenium salts.
Scheme 11: Method for large-scale preparation of S-(trifluoromethyl)dibenzothiophenium salts.
Scheme 12: Triflic acid catalyzed synthesis of 5-(trifluoromethyl)thiophenium salts.
Scheme 13: Trifluoromethylation of β-ketoesters and dicyanoalkylidenes by S-(trifluoromethyl)benzothiophenium ...
Scheme 14: Synthesis of chiral S-(trifluoromethyl)benzothiophenium salt 18 and attempt of enantioselective tri...
Scheme 15: Synthesis of O-(trifluoromethyl)dibenzofuranium salts.
Scheme 16: Photochemical O- and N-trifluoromethylation by 20b.
Scheme 17: Thermal O-trifluoromethylation of phenol by diazonium salt 19a. Effect of the counteranion.
Scheme 18: Thermal O- and N-trifluoromethylations.
Scheme 19: Method of preparation of S-(trifluoromethyl)diphenylsulfonium triflates.
Scheme 20: Reactivity of some S-(trifluoromethyl)diarylsulfonium triflates.
Scheme 21: One-pot synthesis of S-(trifluoromethyl)diarylsulfonium triflates.
Scheme 22: One-pot synthesis of Umemoto’s type reagents.
Scheme 23: Preparation of sulfonium salts by transformation of CF3− into CF3+.
Scheme 24: Selected reactions with the new Yagupolskii reagents.
Scheme 25: Synthesis of heteroaryl-substituted sulfonium salts.
Scheme 26: First neutral S-CF3 reagents.
Scheme 27: Synthesis of Togni reagents. aYield for the two-step procedure.
Scheme 28: Trifluoromethylation of C-nucleophiles with 37.
Scheme 29: Selected examples of trifluoromethylation of S-nucleophiles with 37.
Scheme 30: Selected examples of trifluoromethylation of P-nucleophiles with 35 and 37.
Scheme 31: Trifluoromethylation of 2,4,6-trimethylphenol with 35.
Scheme 32: Examples of O-trifluoromethylation of alcohols with 35 in the presence of 1 equiv of Zn(NTf2)2.
Scheme 33: Formation of trifluoromethyl sulfonates from sulfonic acids and 35.
Scheme 34: Organocatalytic α-trifluoromethylation of aldehydes with 37.
Scheme 35: Synthesis of reagent 42 and mechanism of trifluoromethylation.
Scheme 36: Trifluoromethylation of β-ketoesters and dicyanoalkylidenes with 42.
