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Search for "alkyl bromide" in Full Text gives 26 result(s) in Beilstein Journal of Organic Chemistry.
Copper-promoted C5-selective bromination of 8-aminoquinoline amides with alkyl bromides
- Changdong Shao,
- Chen Ma,
- Li Li,
- Jingyi Liu,
- Yanan Shen,
- Chen Chen,
- Qionglin Yang,
- Tianyi Xu,
- Zhengsong Hu,
- Yuhe Kan and
- Tingting Zhang
Beilstein J. Org. Chem. 2024, 20, 155–161, doi:10.3762/bjoc.20.14
- , the amount of alkyl bromide and temperature affected the reaction significantly (Table 1, entries 20 and 21). Finally, control experiments demonstrated that copper promoted the transformation and a base was the indispensable factor for the reaction (Table 1, entries 22–24). Therefore, a facile and
Graphical Abstract
Scheme 1: Methods for the C5-selective bromination of 8-aminoquinoline amides.
Scheme 2: Substrate scope of the 8-aminoquinoline amides. Reaction conditions: 1 (0.2 mmol), 2a (0.8 mmol), C...
Scheme 3: Substrate scope of the bromoalkanes. Reaction conditions: 1a (0.2 mmol), 2 (0.8 mmol), Cu(OAc)2·H2O...
Scheme 4: Further substrate scope investigations and gram-scale application.
Scheme 5: Control experiments and proposed mechanism.
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
- was selectively alkylated on the primary alcohol to produce 20.2 via the use of dibutyltin oxide as selective reagent for the alkylation of diols [109]. For this reaction, CsF was added to increase the reactivity of the alkyl bromide, likely by a combined effect that includes the interaction of the
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...
Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions
- Surendran Amrutha,
- Sankaran Radhika and
- Gopinathan Anilkumar
Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31
- from C(sp2) to C(sp3). The reaction exhibited good yields, when a secondary alkyl bromide was treated with the alkynyl reagent. They performed the reaction between 4-bromo-1-cyclohexen-1-yltrifluromethane sulfonate and an alkynylmagnesium reagent in the presence of Fe catalyst with bisphosphine, which
Graphical Abstract
Scheme 1: One pot Sonogashira coupling of aryl iodides with arylynols in the presence of iron(III) chloride h...
Scheme 2: The iron-catalyzed Sonogashira coupling of aryl iodides with terminal acetylenes in water under aer...
Scheme 3: Sonogashira coupling of aryl halides and phenylacetylene in the presence of iron nanoparticles.
Scheme 4: Sonogashira coupling catalyzed by a silica-supported heterogeneous Fe(III) catalyst.
Scheme 5: Suggested catalytic cycle for the Sonogashira coupling using a silica-supported heterogeneous Fe(II...
Scheme 6: Chemoselective iron-catalyzed cross coupling of 4-bromo-1-cyclohexen-1-yltrifluromethane sulfonate ...
Scheme 7: Fe-catalyzed Sonogashira coupling between terminal alkynes and aryl iodides.
Scheme 8: Iron-catalyzed domino Sonogashira coupling and hydroalkoxylation.
Scheme 9: Sonogashira coupling of aryl halides and phenylacetylene in the presence of Fe(III) acetylacetonate...
Scheme 10: Sonogashira coupling of aryl iodides and alkynes with Fe(acac)3/2,2-bipyridine catalyst.
Scheme 11: Sonogashira cross-coupling of terminal alkynes with aryl iodides in the presence of Fe powder/ PPh3...
Scheme 12: α-Fe2O3 nanoparticles-catalyzed coupling of phenylacetylene with aryl iodides.
Scheme 13: Sonogashira cross-coupling reaction between phenylacetylene and 4-substituted iodobenzenes catalyze...
Scheme 14: One-pot synthesis of 2-arylbenzo[b]furans via tandem Sonogashira coupling–cyclization protocol.
Scheme 15: Suggested mechanism of the Fe(III) catalyzed coupling of o-iodophenol with acetylene derivatives.
Scheme 16: Fe3O4@SiO2/Schiff base/Fe(II)-catalyzed Sonogashira–Hagihara coupling reaction.
Scheme 17: Sonogashira coupling using the Fe(II)(bdmd) catalyst in DMF/1,4-dioxane.
Scheme 18: Synthesis of 7-azaindoles using Fe(acac)3 as catalyst.
Scheme 19: Plausible mechanistic pathway for the synthesis of 7-azaindoles.
Scheme 20: Synthesis of Co@imine-POP catalyst.
Scheme 21: Sonogashira coupling of various arylhalides and phenylacetylene in the presence of Co@imine-POP cat...
Scheme 22: Sonogashira coupling of aryl halides and phenylacetylene using Co-DMM@MNPs/chitosan.
Scheme 23: Sonogashira cross-coupling of aryl halides with terminal acetylenes in the presence of Co-NHC@MWCNT...
Scheme 24: Sonogashira cross-coupling of aryl halides with terminal acetylenes in the presence of Co nanoparti...
Scheme 25: Sonogashira coupling reaction of aryl halides with phenylacetylene in the presence of Co nanopartic...
Scheme 26: PdCoNPs-3DG nanocomposite-catalyzed Sonogashira cross coupling of aryl halide and terminal alkynes.
Scheme 27: Sonogashira cross-coupling of aryl halides and phenylacetylene in the presence of graphene-supporte...
Scheme 28: Sonogashira cross-coupling with Pd/Co ANP-PPI-graphene.
Scheme 29: Pd-Co-1(H)-catalyzed Sonogashira coupling reaction.
Scheme 30: The coupling of aryl halides with terminal alkynes using cobalt hollow nanospheres as catalyst.
Scheme 31: A plausible mechanism for the cobalt-catalyzed Sonogashira coupling reaction.
Scheme 32: Sonogashira cross-coupling reaction of arylhalides with phenylacetylene catalyzed by Fe3O4@PEG/Cu-C...
Scheme 33: Plausible mechanism of Sonogashira cross-coupling reaction catalyzed by Fe3O4@PEG/Cu-Co.
Scheme 34: Sonogashira coupling reaction of para-substituted bromobenzenes with phenylacetylene in the presenc...
Scheme 35: Possible mechanism for the visible light-assisted cobalt complex-catalyzed Sonogashira coupling. (R...
Scheme 36: Sonogashira cross-coupling of aryl halides and phenylacetylene using cobalt as additive.
Scheme 37: Plausible mechanism of Sonogashira cross-coupling reaction over [LaPd*]. (Reproduced with permissio...
Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution
- Ryan M. Alam and
- John J. Keating
Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127
- alkylindazoles. Initial screening of various conditions revealed that the combination of sodium hydride (NaH) in tetrahydrofuran (THF) (in the presence of an alkyl bromide), represented a promising system for N-1 selective indazole alkylation. For example, among fourteen C-3 substituted indazoles examined, we
Graphical Abstract
Figure 1: Examples of indazole natural products (1 and 2) and synthetic biologically active indazole derivati...
Scheme 1: Synthetic approaches to N-1 substituted indazole derivatives [12-14].
Scheme 2: N-Alkylation of indazole 9 under Mitsunobu conditions shows a strong preference (ratio N-1 (10):N-2...
Figure 2: Observation of a 1H–13C correlation between the C-7a (blue circle) or C-3 (red circle) atom of the ...
Figure 3: C-3 substituted indazole derivatives (12–24) employed to investigate C-3 substituent effects on ind...
Scheme 3: Proposed mechanism for the regioselective N-1 alkylation of indazoles 9, 19, and 21–24 in the prese...
N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles
- Joseane A. Mendes,
- Paulo R. R. Costa,
- Miguel Yus,
- Francisco Foubelo and
- Camilla D. Buarque
Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86
Graphical Abstract
Scheme 1: General strategy for the enantioselective synthesis of N-containing heterocycles from N-tert-butane...
Scheme 2: Methodologies for condensation of aldehydes and ketones with tert-butanesulfinamides (1).
Scheme 3: Transition models for cis-aziridines and trans-aziridines.
Scheme 4: Mechanism for the reduction of N-tert-butanesulfinyl imines.
Scheme 5: Transition models for the addition of organomagnesium and organolithium compounds to N-tert-butanes...
Scheme 6: Synthesis of 2,2-dibromoaziridines 15 from aldimines 14 and bromoform, and proposed non-chelation-c...
Scheme 7: Diastereoselective synthesis of aziridines from tert-butanesulfinyl imines.
Scheme 8: Synthesis of vinylaziridines 22 from aldimines 14 and 1,3-dibromopropene 23, and proposed chelation...
Scheme 9: Synthesis of vinylaziridines 27 from aldimines 14 and α-bromoesters 26, and proposed transition sta...
Scheme 10: Synthesis of 2-chloroaziridines 28 from aldimines 14 and dichloromethane, and proposed transition s...
Scheme 11: Synthesis of cis-vinylaziridines 30 and 31 from aldimines 14 and bromomethylbutenolide 29.
Scheme 12: Synthesis of 2-chloro-2-aroylaziridines 36 and 32 from aldimines 14, arylnitriles 34, and silyldich...
Scheme 13: Synthesis of trifluoromethylaziridines 39 and proposed transition state of the aziridination.
Scheme 14: Synthesis of aziridines 42 and proposed state transition.
Scheme 15: Synthesis of 1-substituted 2-azaspiro[3.3]heptanes, 1-phenyl-2-azaspiro[3.4]octane and 1-phenyl-2-a...
Scheme 16: Synthesis of 1-substituted 2,6-diazaspiro[3.3]heptanes 48 from chiral imines 14 and 1-Boc-azetidine...
Scheme 17: Synthesis of β-lactams 52 from chiral imines 14 and dimethyl malonate (49).
Scheme 18: Synthesis of spiro-β-lactam 57 from chiral (RS)-N-tert-butanesulfinyl isatin ketimine 53 and ethyl ...
Scheme 19: Synthesis of β-lactam 60, a precursor of (−)-batzelladine D (61) and (−)-13-epi-batzelladine D (62)...
Scheme 20: Rhodium-catalyzed asymmetric synthesis of 3-substituted pyrrolidines 66 from chiral imine (RS)-63 a...
Scheme 21: Asymmetric synthesis of 1,3-disubstituted isoindolines 69 and 70 from chiral imine 67.
Scheme 22: Asymmetric synthesis of cis-2,5-disubstituted pyrrolidines 73 from chiral imine (RS)-71.
Scheme 23: Asymmetric synthesis of 3-hydroxy-5-substituted pyrrolidin-2-ones 77 from chiral imine (RS)-74.
Scheme 24: Asymmetric synthesis of 4-hydroxy-5-substituted pyrrolidin-2-ones 80 from chiral imines 79.
Scheme 25: Asymmetric synthesis of 3-pyrrolines 82 from chiral imines 14 and ethyl 4-bromocrotonate (81).
Scheme 26: Asymmetric synthesis of γ-amino esters 84, and tetramic acid derivative 86 from chiral imines (RS)-...
Scheme 27: Asymmetric synthesis of α-methylene-γ-butyrolactams 90 from chiral imines (Z,SS)-87 and ethyl 2-bro...
Scheme 28: Asymmetric synthesis of methylenepyrrolidines 92 from chiral imines (RS)-14 and 2-(trimethysilylmet...
Scheme 29: Synthesis of dibenzoazaspirodecanes from cyclic N-tert-butanesulfinyl imines.
Scheme 30: Stereoselective synthesis of cyclopenta[c]proline derivatives 103 from β,γ-unsaturated α-amino acid...
Scheme 31: Stereoselective synthesis of alkaloids (−)-angustureine (107) and (−)-cuspareine (108).
Scheme 32: Stereoselective synthesis of alkaloids (−)-pelletierine (112) and (+)-coniine (117).
Scheme 33: Synthesis of piperidine alkaloids (+)-dihydropinidine (122a), (+)-isosolenopsin (122b) and (+)-isos...
Scheme 34: Stereoselective synthesis of the alkaloids(+)-sedamine (125) from chiral imine (SS)-119.
Scheme 35: Stereoselective synthesis of trans-5-hydroxy-6-substituted-2-piperidinones 127 and 129 from chiral ...
Scheme 36: Stereoselective synthesis of trans-5-hydroxy-6-substituted ethanone-2-piperidinones 132 from chiral...
Scheme 37: Stereoselective synthesis of trans-3-benzyl-5-hydroxy-6-substituted-2-piperidinones 136 from chiral...
Scheme 38: Stereoselective synthesis of trans-5-hydroxy-6-substituted 2-piperidinones 139 from chiral imine 138...
Scheme 39: Stereoselective synthesis of ʟ-hydroxypipecolic acid 145 from chiral imine 144.
Scheme 40: Synthesis of 1-substituted isoquinolones 147, 149 and 151.
Scheme 41: Stereoselective synthesis of 3-substituted dihydrobenzo[de]isoquinolinones 154.
Scheme 42: Enantioselective synthesis of alkaloids (S)-1-benzyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (...
Scheme 43: Enantioselective synthesis of alkaloids (−)-cermizine B (171) and (+)-serratezomine E (172) develop...
Scheme 44: Stereoselective synthesis of (+)-isosolepnosin (177) and (+)-solepnosin (178) from homoallylamine d...
Scheme 45: Stereoselective synthesis of tetrahydroquinoline derivatives 184, 185 and 187 from chiral imines (RS...
Scheme 46: Stereoselective synthesis of pyridobenzofuran and pyridoindole derivatives 193 from homopropargylam...
Scheme 47: Stereoselective synthesis of 2-substituted 1,2,5,6-tetrahydropyridines 196 from chiral imines (RS)-...
Scheme 48: Stereoselective synthesis of 2-substituted trans-2,6-disubstituted piperidine 199 from chiral imine...
Scheme 49: Stereoselective synthesis of cis-2,6-disubstituted piperidines 200, and alkaloid (+)-241D, from chi...
Scheme 50: Stereoselective synthesis of 6-substituted piperidines-2,5-diones 206 and 1,7-diazaspiro[4.5]decane...
Scheme 51: Stereoselective synthesis of spirocyclic oxindoles 210 from chiral imines (RS)-53.
Scheme 52: Stereoselective synthesis of azaspiro compound 213 from chiral imine 211.
Scheme 53: Stereoselective synthesis of tetrahydroisoquinoline derivatives from chiral imines (RS)-214.
Scheme 54: Stereoselective synthesis of (−)-crispine A 223 from chiral imine (RS)-214.
Scheme 55: Synthesis of (−)-harmicine (228) using tert-butanesulfinamide through haloamide cyclization.
Scheme 56: Stereoselective synthesis of tetraponerines T1–T8.
Scheme 57: Stereoselective synthesis of phenanthroindolizidines 246a and (−)-tylophorine (246b), and phenanthr...
Scheme 58: Stereoselective synthesis of indoline, tetrahydroquinoline and tetrahydrobenzazepine derivatives 253...
Scheme 59: Stereoselective synthesis of (+)-epohelmin A (258) and (+)-epohelmin B (260) from aldimine (RS)-79.
Scheme 60: Stereoselective synthesis of (−)-epiquinamide (266) from chiral aldimine (SS)-261.
Scheme 61: Synthesis synthesis of (–)-hippodamine (273) and (+)-epi-hippodamine (272) using chiral sulfinyl am...
Scheme 62: Stereoselective synthesis of (+)-grandisine D (279) and (+)-amabiline (283).
Scheme 63: Stereoselective synthesis of (−)-epiquinamide (266) and (+)-swaisonine (291) from aldimine (SS)-126....
Scheme 64: Stereoselective synthesis of (+)-C(9a)-epi-epiquinamide (294).
Scheme 65: Stereoselective synthesis of (+)-lasubine II (298) from chiral aldimine (SS)-109.
Scheme 66: Stereoselective synthesis of (−)-epimyrtine (300a) and (−)-lasubine II (ent-302) from β-amino keton...
Scheme 67: Stereoselective synthesis of (−)-tabersonine (310), (−)-vincadifformine (311), and (−)-aspidospermi...
Scheme 68: Stereoselective synthesis of (+)-epohelmin A (258) and (+)-epohelmin B (260) from aldehyde 313 and ...
Scheme 69: Total synthesis of (+)-lysergic acid (323) from N-tert-butanesulfinamide (RS)-1.
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
- radical 5•, which (depending on the EWG) can either reduce another molecule of 2 via a SET process or via an atom transfer (AT) process and propagate the chain reaction [21]. The SET route directly generates 2• and iminium ion intermediate 6, but the AT goes through alkyl bromide 7, before generating 6
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.
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
- Lucas Guillemard and
- Joanna Wencel-Delord
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
Graphical Abstract
Figure 1: Concept of dual synergistic catalysis.
Figure 2: Classification of catalytic systems involving two catalysts.
Figure 3: General mechanism for the dual nickel/photoredox catalytic system.
Figure 4: General mechanisms for C–H activation catalysis involving different reoxidation strategies.
Figure 5: Indole synthesis via dual C–H activation/photoredox catalysis.
Figure 6: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 7: Oxidative Heck reaction on arenes via the dual catalysis.
Figure 8: Proposed mechanism for the Heck reaction on arenes via dual catalysis.
Figure 9: Oxidative Heck reaction on phenols via the dual catalysis.
Figure 10: Proposed mechanism for the Heck reaction on phenols via dual catalysis.
Figure 11: Carbazole synthesis via dual C–H activation/photoredox catalysis.
Figure 12: Proposed mechanism for the carbazole synthesis via dual catalysis.
Figure 13: Carbonylation of enamides via the dual C–H activation/photoredox catalysis.
Figure 14: Proposed mechanism for carbonylation of enamides via dual catalysis.
Figure 15: Annulation of benzamides via the dual C–H activation/photoredox catalysis.
Figure 16: Proposed mechanism for the annulation of benzamides via dual catalysis.
Figure 17: Synthesis of indoles via the dual C–H activation/photoredox catalysis.
Figure 18: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 19: General concept of dual catalysis merging C–H activation and photoredox catalysis.
Figure 20: The first example of dual catalysis merging C–H activation and photoredox catalysis.
Figure 21: Proposed mechanism for the C–H arylation with diazonium salts via dual catalysis.
Figure 22: Dual catalysis merging C–H activation/photoredox using diaryliodonium salts.
Figure 23: Direct arylation via the dual catalytic system reported by Xu.
Figure 24: Direct arylation via dual catalytic system reported by Balaraman.
Figure 25: Direct arylation via dual catalytic system reported by Guo.
Figure 26: C(sp3)–H bond arylation via the dual Pd/photoredox catalytic system.
Figure 27: Acetanilide derivatives acylation via the dual C–H activation/photoredox catalysis.
Figure 28: Proposed mechanism for the C–H acylation with α-ketoacids via dual catalysis.
Figure 29: Acylation of azobenzenes via the dual catalysis C–H activation/photoredox.
Figure 30: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 31: Proposed mechanism for the C2-acylation of indoles with aldehydes via dual catalysis.
Figure 32: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 33: Perfluoroalkylation of arenes via the dual C–H activation/photoredox catalysis.
Figure 34: Proposed mechanism for perfluoroalkylation of arenes via dual catalysis.
Figure 35: Sulfonylation of 1-naphthylamides via the dual C–H activation/photoredox catalysis.
Figure 36: Proposed mechanism for sulfonylation of 1-naphthylamides via dual catalysis.
Figure 37: meta-C–H Alkylation of arenes via visible-light metallaphotocatalysis.
Figure 38: Alternative procedure for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 39: Proposed mechanism for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 40: C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 41: Proposed mechanism for C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 42: Undirected C–H aryl–aryl cross coupling via dual gold/photoredox catalysis.
Figure 43: Proposed mechanism for the undirected C–H aryl–aryl cross-coupling via dual catalysis.
Figure 44: Undirected C–H arylation of (hetero)arenes via dual manganese/photoredox catalysis.
Figure 45: Proposed mechanism for the undirected arylation of (hetero)arenes via dual catalysis.
Figure 46: Photoinduced C–H arylation of azoles via copper catalysis.
Figure 47: Photo-induced C–H chalcogenation of azoles via copper catalysis.
Figure 48: Decarboxylative C–H adamantylation of azoles via dual cobalt/photoredox catalysis.
Figure 49: Proposed mechanism for the C–H adamantylation of azoles via dual catalysis.
Figure 50: General mechanisms for the “classical” (left) and Cu-free variant (right) Sonogoshira reaction.
Figure 51: First example of a dual palladium/photoredox catalysis for Sonogashira-type couplings.
Figure 52: Arylation of terminal alkynes with diazonium salts via dual gold/photoredox catalysis.
Figure 53: Proposed mechanism for the arylation of terminal alkynes via dual catalysis.
Figure 54: C–H Alkylation of alcohols promoted by H-atom transfer (HAT).
Figure 55: Proposed mechanism for the C–H alkylation of alcohols promoted by HAT.
Figure 56: C(sp3)–H arylation of latent nucleophiles promoted by H-atom transfer.
Figure 57: Proposed mechanism for the C(sp3)–H arylation of latent nucleophiles promoted by HAT.
Figure 58: Direct α-arylation of alcohols promoted by H-atom transfer.
Figure 59: Proposed mechanism for the direct α-arylation of alcohols promoted by HAT.
Figure 60: C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 61: Proposed mechanism for the C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 62: C–H functionalization of nucleophiles via excited ketone/nickel dual catalysis.
Figure 63: Proposed mechanism for the C–H functionalization enabled by excited ketones.
Figure 64: Selective sp3–sp3 cross-coupling promoted by H-atom transfer.
Figure 65: Proposed mechanism for the selective sp3–sp3 cross-coupling promoted by HAT.
Figure 66: Direct C(sp3)–H acylation of amines via dual Ni/photoredox catalysis.
Figure 67: Proposed mechanism for the C–H acylation of amines via dual Ni/photoredox catalysis.
Figure 68: C–H hydroalkylation of internal alkynes via dual Ni/photoredox catalysis.
Figure 69: Proposed mechanism for the C–H hydroalkylation of internal alkynes.
Figure 70: Alternative procedure for the C–H hydroalkylation of ynones, ynoates, and ynamides.
Figure 71: Allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 72: Proposed mechanism for the allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 73: Asymmetric allylation of aldehydes via dual Cr/photoredox catalysis.
Figure 74: Proposed mechanism for the asymmetric allylation of aldehydes via dual catalysis.
Figure 75: Aldehyde C–H functionalization promoted by H-atom transfer.
Figure 76: Proposed mechanism for the C–H functionalization of aldehydes promoted by HAT.
Figure 77: Direct C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 78: Proposed mechanism for the C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 79: Direct C–H trifluoromethylation of strong aliphatic bonds promoted by HAT.
Figure 80: Proposed mechanism for the C–H trifluoromethylation of strong aliphatic bonds.
The McKenna reaction – avoiding side reactions in phosphonate deprotection
- Katarzyna Justyna,
- Joanna Małolepsza,
- Damian Kusy,
- Waldemar Maniukiewicz and
- Katarzyna M. Błażewska
Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119
- the side reactions, which originate from BTMS itself, and those resulting from not having taken appropriate precautions during the subsequent solvolysis step. By being alerted to the water-sensitive character of BTMS and the formation of the alkylating agent alkyl bromide (Scheme 1), side reactions
- for studying the possibility of an N-alkylation by alkyl bromide, formed during the silylation step. Finally, compound 13 was included to study the possibility of a chlorine for bromine exchange reaction. The phosphonocarboxylates 8 and 9 were used to explore whether the carboxyester group could be
- out overnight [26][27]. However, during the first step of the McKenna reaction, alkyl bromide is formed (Scheme 1) representing an alkylating agent, which upon prolonged reaction time, may lead to side product formation. In order to study this process, we chose phosphonate analogs 9a–d and acryl amide
Graphical Abstract
Scheme 1: Schematic overview of the McKenna reaction including the decomposition of BTMS in protic solvents. ...
Figure 1: The model compounds used for this study (in red: the functionality of the molecules vulnerable to s...
Scheme 2: Formation of the side products derived from 10. Conditions: An equimolar mixture of propargylamide ...
Scheme 3: Addition of HBr to compound 11.
Scheme 4: N-Alkylation of 9.
Scheme 5: N-Alkylation of 12.
Scheme 6: Exchange of the chlorine substituent with bromine in 2-chloro-N-phenethylacetamide (13) under McKen...
Diversity-oriented synthesis of 17-spirosteroids
- Benjamin Laroche,
- Thomas Bouvarel,
- Martin Louis-Sylvestre and
- Bastien Nay
Beilstein J. Org. Chem. 2020, 16, 880–887, doi:10.3762/bjoc.16.79
- stirring for 1.5 hours, the alkyl bromide (2 mmol) was added dropwise at 0 °C and the resulting mixture was stirred at room temperature for 16 hours. The reaction was quenched by the addition of water (10 mL). The solution was extracted with diethyl ether (3 × 20 mL), the combined organic layers were then
Graphical Abstract
Scheme 1: Two diversity-oriented strategies: (a) Diversity installed during the construction of the skeleton;...
Figure 1: Structure of four 17-ethynyl-17-hydroxysteroids 1–4 (top) and how they could be used to generate di...
Scheme 2: Synthesis of spirocyclic steroid derivatives by the RCEYM reaction. Conditions: (a) NaH (2 equiv), ...
Figure 2: Structure of metathesis catalysts.
Scheme 3: One-pot RCEYM/Diels–Alder reaction strategy applied to the mestranol and lynestrenol cores. Notes: a...
Figure 3: Rationale for the observed stereochemistry: (a) NOESY correlations observed on compound 16b, showin...
Aldehydes as powerful initiators for photochemical transformations
- Maria A. Theodoropoulou,
- Nikolaos F. Nikitas and
- Christoforos G. Kokotos
Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76
- hypothesis was that the excitation of benzaldehyde (8) to the singlet state followed by ISC to the triplet state could lead to a HAT process from the THF solvent molecule, resulting in the α-hydroxybenzyl radicals 10 or 11 and solvent radicals, which could then undergo coupling with an alkyl bromide in the
Graphical Abstract
Scheme 1: Norrish type I and II dissociations.
Scheme 2: Proposed radical pair formation after the photolysis of benzaldehyde (8).
Scheme 3: Aldehydes in the Paterno–Büchi reaction.
Scheme 4: 2,3-Diazabicyclo[2.2.1]hept-2-ene (DBH).
Scheme 5: Dissociation pathways of benzaldehyde.
Scheme 6: Reactions that lead to polarized products detectable by CIDNP.
Scheme 7: MMA (26), DEABP (27), and Michler’s ketone (28).
Scheme 8: Radical intermediates of DEABP.
Scheme 9: Photoinitiated polymerization of monomeric MMA (26) using the quinoxalines 32 and benzaldehyde (8).
Scheme 10: Acetone (4) and formaldehyde (35) as photografting initiators.
Scheme 11: Photografting by employing acetaldehyde (36) as the photoinitiator.
Scheme 12: Proposed photolysis mechanism for aliphatic ketones 44 and formaldehyde (35).
Scheme 13: Initiator 50, reductant 51, and benzaldehyde derivatives 52–54 for the polymerization of the methac...
Scheme 14: Proposed mechanism of the photomediated atom transfer radical polymerization employing the benzalde...
Scheme 15: cis/trans isomerization employing triplet states of photosensitizers.
Scheme 16: Salicylaldehyde (68) forms an internal hydrogen bond.
Scheme 17: Olefin isomerization via energy transfer from a carbonyl compound.
Scheme 18: Mechanistic pathways for the Paterno–Büchi reaction.
Scheme 19: Isomeric oxetanes formed after photochemical addition of aryl aldehydes to 2-butenes.
Scheme 20: Rotation of the C3–C4 bond of the biradical intermediate may lead to all four conformations.
Scheme 21: Photolysis products of benzaldehyde (8) in different solvents. a) In benzene or ethanol. b) In hex-...
Scheme 22: N-tert-Butylbenzamide formation proceeds via a benzoyl radical.
Scheme 23: Photochemical pinacol coupling.
Scheme 24: Photochemical ATRA catalyzed by 4-anisaldehyde (52).
Scheme 25: Proposed triplet sensitization mechanism of the ATRA reaction in the presence of 4-anisaldehyde (52...
Scheme 26: Benzaldehyde-mediated photoredox CDC reaction: compatible amides and ethers.
Scheme 27: Photoredox cross-dehydrogenative coupling (CDC) conditions and proposed reaction mechanism.
Scheme 28: Optimized conditions for the photoredox merger reaction.
Scheme 29: Proposed mechanism for the C(sp3)–H alkylation/arylation of ethers.
Scheme 30: Substrate scope for the photochemical alkylation of ethers.
Scheme 31: C(sp3)–H Functionalization of N-containing molecules.
Scheme 32: Substrate scope for the photochemical alkylation of N-containing molecules.
Scheme 33: Additional products yielded by the photochemical alkylation reaction of N-containing molecules.
Scheme 34: C(sp3)–H functionalization of thioethers.
Scheme 35: Proposed mechanism for the C(sp3)–H alkylation/arylation of N-containing molecules and thioethers.
Scheme 36: Hydroacylation using 4-cyanobenzaldehyde (53) as the photoinitiator.
Scheme 37: Selectivity for the formation of the α,α-disubstituted aldehydes.
Scheme 38: Substrate scope for the photochemical addition of aldehydes to Michael acceptors.
Scheme 39: Proposed mechanism for the hydroacylation of Michael acceptors using 4-cyanobenzaldehyde (53) as th...
Scheme 40: Catalytic arylation of aromatic aldehydes by aryl bromides in which the reaction product acts as th...
Scheme 41: Proposed mechanism for the catalytic arylation of benzaldehydes by aryl bromides in which the react...
Scheme 42: Functionalization of the chiral cyclobutanes 180.
Scheme 43: Optimized reaction conditions and proposed mechanism for the sulfonylcyanation of cyclobutenes.
Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0
- Bernd Strehmel,
- Christian Schmitz,
- Ceren Kütahya,
- Yulian Pang,
- Anke Drewitz and
- Heinz Mustroph
Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40
- presented for in situ generation of Cu(I) to initiate the polymerization with the alkyl bromide. In this system, the Cu(II) complex was exposed to UV light to form Cu(I) which can react with alkyl halide resulting in generation of reactive radicals and Cu(II), Scheme 9. Those reactive radicals add monomer
Graphical Abstract
Scheme 1: Structural patterns of several symmetric cyanines relating to trimethines (I), pentamethines (II), ...
Scheme 2: 1-Substituted 2,3,3-trimethylindolium-, 2,3,3-benzo[e]indolium-, and 2,3,3-benzo[c,d]indolium salts...
Scheme 3: Substitution of the chlorine substituent at the meso-position by a stronger nucleophilic moiety B [68].
Scheme 4: Structure of alternative chain builders for synthesis of heptamethines.
Figure 1: Simplified process chart of photophysical processes occurring in NIR absorbers.
Scheme 5: Chemical structure of the electron acceptors that were from iodonium cations 88 and triazines 89.
Figure 2: Photoinduced electron transfer under different scenarios in which each example exhibits an intrinsi...
Scheme 6: Photoexcited absorber 33 results in reaction with an iodonium cation in the respective cation radic...
Scheme 7: Reaction scheme of absorbers comprising in the molecules center a five ring bridged moiety. This le...
Scheme 8: Structure of donor compounds used in a three component system.
Figure 3: Cationic photopolymerization of an epoxide (Epikote 828) initiated by excitation of the absorber 36...
Scheme 9: Different modes of photoinitiated ATRP using UV, visible and NIR light.
Scheme 10: The structure of Sens used in photo-ATRP.
Figure 4: Comparison of the GPC traces of precursor PMMA with a) chain extended PMMA and b) PMMA-b-PS. Condit...
Figure 5: Spectral changes of the solution of 48 in the presence of [Cu(L)]Br2 (L: tris(2-pyridylmethyl)amine...
Scheme 11: Photoinduced CuAAC reactions in which photochemical reactions result in formation of the Cu(I) cata...
Scheme 12: Model reaction between benzyl azide and phenyacetylene using the absorber 48 as NIR sensitizer at 7...
Figure 6: Block copolymerization of the precursors PS-N3 and Alkyne-PCL results in the block copolymer PS-b-P...
Figure 7: UV–vis–NIR absorption changes of the solution of 48 in the presence of PMDETA, phenylacetylene and ...
Scheme 13: Workflow to design and process new materials in a setup based on an intelligent DoE to develop tech...
Scheme 14: Illustration of the iDoE setting up experiments suggested and analyzed by the A.I. After defining t...
Scheme 15: Classification of the factors for the formation of polymer networks by NIR-photocuring depending on...
The chemistry and biology of mycolactones
- Matthias Gehringer and
- Karl-Heinz Altmann
Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159
Graphical Abstract
Figure 1: Initial proposal for the core macrolactone structure (left) and the established complete structure ...
Figure 2: Mycolactone congeners and their origins.
Figure 3: Misassigned mycolactone E structure according to Small et al. [50] (11) and the correct structure (6) f...
Figure 4: Schematic illustration of Kishi’s improved mycolactone TLC detection method exploiting derivatizati...
Figure 5: Fluorescent probes derived from natural mycolactone A/B (1a,b) or its synthetic 8-desmethyl analogs...
Figure 6: Tool compounds used by Pluschke and co-workers for elucidating the molecular targets of mycolactone...
Figure 7: Synthetic strategies towards the extended mycolactone core. A) General strategies. B) Kishi’s appro...
Scheme 1: Kishi’s 1st generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 2: Kishi’s 2nd generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 3: Kishi’s 3rd generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 4: Negishi’s synthesis of the extended core structure of mycolactones. Reagents and conditions: a) (i) ...
Scheme 5: Burkart’s (incomplete) 1st generation approach towards the extended core structure of mycolactones....
Scheme 6: Burkart’s (incomplete) 1st, 2nd and 3rd generation approach towards the extended mycolactone core s...
Scheme 7: Altmann’s synthesis of alkyl iodide 91. Reagents and conditions: a) (i) PMB-trichloroacetimidate, T...
Scheme 8: Final steps of Altmann’s synthesis of the extended core structure of mycolactones. Reagents and con...
Scheme 9: Basic principles of the Aggarwal lithiation–borylation homologation process [185,186].
Scheme 10: Aggarwal’s synthesis of the C1–C11 fragment of the mycolactone core. Reagents and conditions: a) Cl...
Scheme 11: Aggarwal’s synthesis of the linear C1–C20 fragment of the mycolactone core. Reagents and conditions...
Figure 8: Synthetic strategies towards the mycolactone A/B lower side chain.
Scheme 12: Gurjar and Cherian’s synthesis of the C1’–C8’ fragment of the mycolactone A/B pentaenoate side chai...
Scheme 13: Gurjar and Cherian’s synthesis of the benzyl-protected mycolactone A/B pentaenoate side chain. Reag...
Scheme 14: Kishi’s synthesis of model compounds for elucidating the stereochemistry of the C7’–C16’ fragment o...
Scheme 15: Kishi’s synthesis of the mycolactone A/B pentaenoate side chain. (a) (i) NaH, (EtO)2P(O)CH2CO2Et, T...
Scheme 16: Feringa and Minnaard's incomplete synthesis of mycolactone A/B pentaenoate side chain. Reagents and...
Scheme 17: Altmann’s approach towards the mycolactone A/B pentaenoate side chain. Reagents and conditions: a) ...
Scheme 18: Negishi’s access to the C1’–C7’ fragment of mycolactone A. Reagents and conditions: a) (i) n-BuLi, ...
Scheme 19: Negishi’s approach to the C1’–C7’ fragment of mycolactone B. Reagents and conditions: a) (i) DIBAL-...
Scheme 20: Negishi’s synthesis of the C8’–C16’ fragment of mycolactone A/B. Reagents and conditions: a) 142, BF...
Scheme 21: Negishi’s assembly of the mycolactone A and B pentaenoate side chains. Reagents and conditions: a) ...
Scheme 22: Blanchard’s approach to the mycolactone A/B pentaenoate side chain. a) (i) Ph3P=C(Me)COOEt, CH2Cl2,...
Scheme 23: Kishi’s approach to the mycolactone C pentaenoate side chain exemplified for the 13’R,15’S-isomer 1...
Scheme 24: Altmann’s (unpublished) synthesis of the mycolactone C pentaenoate side chain. Reagents and conditi...
Scheme 25: Blanchard’s synthesis of the mycolactone C pentaenoate side chain. Reagents and conditions: a) (i) ...
Scheme 26: Kishi’s synthesis of the tetraenoate side chain of mycolactone F exemplified by enantiomer 165. Rea...
Scheme 27: Kishi’s synthesis of the mycolactone E tetraenoate side chain. Reagents and conditions: a) (i) CH2=...
Scheme 28: Wang and Dai’s synthesis of the mycolactone E tetraenoate side chain. Reagents and conditions: a) (...
Scheme 29: Kishi’s synthesis of the dithiane-protected tetraenoate side chain of the minor oxo-metabolite of m...
Scheme 30: Kishi’s synthesis of the mycolactone S1 and S2 pentaenoate side chains. Reagents and conditions: a)...
Scheme 31: Kishi’s 1st generation and Altmann’s total synthesis of mycolactone A/B (1a,b) and Negishi’s select...
Scheme 32: Kishi’s 2nd generation total synthesis of mycolactone A/B (1a,b). Reagents and conditions: a) 2,4,6...
Scheme 33: Blanchard’s synthesis of the 8-desmethylmycolactone core. Reagents and conditions: a) (i) TsCl, TEA...
Scheme 34: Altmann’s (partially unpublished) synthesis of the C20-hydroxylated mycolactone core. Reagents and ...
Scheme 35: Altmann’s and Blanchard’s approaches towards the 11-isopropyl-8-desmethylmycolactone core. Reagents...
Scheme 36: Blanchard’s synthesis of the saturated variant of the C11-isopropyl-8-desmethylmycolactone core. Re...
Scheme 37: Structure elucidation of photo-mycolactones generated from tetraenoate 224.
Scheme 38: Kishi’s synthesis of the linear precursor of the photo-mycolactone B1 lower side chain. Reagents an...
Scheme 39: Kishi’s synthesis of the photo-mycolactone B1 lower side chain. Reagents and conditions: a) LiTMP, ...
Scheme 40: Kishi’s synthesis of a stabilized lower mycolactone side chain. Reagents and conditions: a) (i) TBD...
Scheme 41: Blanchard’s variation of the C12’,C13’,C15’ stereocluster. Reagents and conditions: a) (i) DIBAL-H,...
Scheme 42: Blanchard’s synthesis of aromatic mycolactone polyenoate side chain analogs. Reagents and condition...
Scheme 43: Small’s partial synthesis of a BODIPY-labeled mycolactone derivative and Demangel’s partial synthes...
Scheme 44: Blanchard’s synthesis of the BODIPY-labeled 8-desmethylmycolactones. Reagents and conditions: a) (i...
Scheme 45: Altmann’s synthesis of biotinylated mycolactones. Reagents and conditions: a) (i) CDI, THF, rt, 2 d...
Figure 9: Kishi’s elongated n-butyl carbamoyl mycolactone A/B analog.
A direct method for the N-tetraalkylation of azamacrocycles
- Andrew J. Counsell,
- Angus T. Jones,
- Matthew H. Todd and
- Peter J. Rutledge
Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239
- deprotonate the macrocyclic amine NHs then introducing the appropriate alkyl bromide; however yields were low (35–40%) and the scope limited (in part by the harsh reaction conditions) [34]. Trabaud et al. have prepared a series of N-tetraalkyl ester and carboxylic acid derivatives using bromoester
Graphical Abstract
Scheme 1: N-Tetraalkylation of cyclam (1) and cyclen (2) with alkyl halides in partially miscible aqueous–org...
Figure 1: Ball-and-stick depiction of the crystal structure obtained for [(3)H2](ClO4)2, generated with X-See...
Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate
- Sean P. Bew,
- Glyn D. Hiatt-Gipson,
- Graham P. Mills and
- Claire E. Reeves
Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103
- -(tert-butyldimethylsilyloxy)-2-methylbut-3-en-1-ol (70) in a 78% yield (Scheme 11). Attempted conversion of the 1° alcohol on rac-70 into the corresponding 1° alkyl bromide failed to generate the desired product, instead an intractable tar was formed. Changing our approach Anzini et al. [22
- had in fact generated rac-19. Accounting for this we propose that activation of the 1° alkyl bromide with silver nitrate generates an electrophilic species similar to rac-78 which in the presence of the proximal O-acetate generates a 5-membered electrophilic acyloxonium species based on rac-79/rac-81
- to monoterpene derived O-nitrate ester synthesis was undertaken using (1R,5S)-(−)-myrtenol (84) which was quickly and efficiently converted into the corresponding optically active 1° alkyl bromide 85 which, due to its instability, was used ‘as is’ [55]. Employing our standard silver nitrate
Graphical Abstract
Scheme 1: Simplified overview outlining how a small number of different IPNs are synthesised and are able to ...
Scheme 2: Protocols for the synthesis of O-nitrated alcohols using (±)-isoprene epoxide and 2° alcohols as st...
Scheme 3: Attempted synthesis of O-nitrate ester rac-19 and rac-20 synthesis.
Scheme 4: Olah et al. O-nitrated alcohol syntheses of 23–33 using N-nitro-2,4-6-trimethylpyridinium tetrafluo...
Scheme 5: O-nitration study using 22 and the alcohols 34–37.
Scheme 6: Silver nitrate mediated synthesis of 2-oxopropyl nitrate 43.
Scheme 7: Application of isoprene for the synthesis of precursors to IPNs and synthesis via ‘halide for nitra...
Scheme 8: Synthesis of (E)-3-methyl-4-chlorobut-2-en-1-ol ((E)-60) and (Z)-3-methyl-4-chlorobut-2-en-1-ol ((Z...
Scheme 9: Using NOESY interactions to establish the conformations of the C=C bonds within (E)-10 and (Z)-9.
Scheme 10: Synthesis of isoprene nitrates (E)-11 and (Z)-12 from ketone 63.
Scheme 11: Attempted synthesis of rac-8 from O-mesylate rac-71.
Scheme 12: Synthesis of O-nitrate 73 from O-mesylate 72.
Scheme 13: Attempted synthesis of 2° alcohol containing 1° nitrate ester rac-19 and the unexpected synthesis o...
Scheme 14: Synthesis of monoterpene derived (1R,5S)-(−)-myrtenol nitrate 86.
Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems
- Kirk W. Shimkin and
- Donald A. Watson
Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248
- -withdrawing groups including esters, ketones and nitro groups were tolerated in the alkyl bromide coupling partner (Scheme 10). In addition, the reaction shows excellent functional group compatibility with respect to the styrene coupling partner, tolerating ethers, nitriles, chlorides and amines. Notably
- for the exo-methylene products. The high levels of distal selectivity are proposed to arise from steric contributions. The intermediate alkyl bromide that results from the initial atom transfer possesses two possible sites of elimination. The authors propose that the distal hydrogen is more accessible
- the alkyl bromide coupling partner was changed to an α-bromo keto ester, the radical addition is followed by a tautomerization/cyclization event that provides dihydrofurans in excellent yields [38]. The radical formation/addition events proceed largely in the same manner as the aforementioned
Graphical Abstract
Scheme 1: Reactivity of nitronate anions towards alkyl electrophiles.
Scheme 2: Ligands tested in the alkylation of nitroalkanes with alkyl halides. aNaOt-Bu as base, hexanes as s...
Scheme 3: Scope of the copper-catalyzed nitroalkane benzylation.
Scheme 4: Application of the nitro-alkylation reaction to the synthesis of phentermine.
Scheme 5: Possible mechanism of the thermal redox process.
Scheme 6: Scope of the reaction of nitroalkanes with α-bromocarbonyls.
Scheme 7: Synthesis of highly congested β-amino acids.
Scheme 8: Copper-catalyzed alkenylation reactions.
Scheme 9: Proposed mechanism of the copper-catalyzed alkenylation reaction.
Scheme 10: Scope of the copper-catalyzed alkenylation of tertiary electrophiles.
Scheme 11: Scope of the exo-methylene styrene synthesis.
Scheme 12: Phenol-directed synthesis of Z-alkenes.
Scheme 13: Scope of the phenol-directed Z-alkene synthesis.
Scheme 14: Rationale for the formal [3 + 2] cycloaddition.
Scheme 15: Scope of the formal [3 + 2] cycloaddition.
Scheme 16: Benzylation of styrenes using copper catalysis.
Scheme 17: Copper-catalyzed carboiodination of alkynes.
Scheme 18: Copper-catalyzed trans-carbohalogenation of alkynes. aNaI (2 equiv) was added.
Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes
- Luke J. O’Driscoll,
- Sissel S. Andersen,
- Marta V. Solano,
- Dan Bendixen,
- Morten Jensen,
- Troels Duedal,
- Jess Lycoops,
- Cornelia van der Pol,
- Rebecca E. Sørensen,
- Karina R. Larsen,
- Kenneth Myntman,
- Christian Henriksen,
- Stinne W. Hansen and
- Jan O. Jeppesen
Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125
- noted that the reaction with CsOH·H2O used an alkyl bromide whereas that with DBU used the more reactive alkyl iodide analogue. Therefore, this effect may not relate to the change of base alone. In summary, the use of DBU as a deprotecting reagent was found to be high-yielding, consistent and more
Graphical Abstract
Figure 1: The sequential, reversible oxidation of TTF (1) to its stable radical cation (2) and dication (3) s...
Figure 2: Structures and possible substitution positions of MPTTFs (4) and BPTTFs (5).
Scheme 1: Large-scale synthesis of 6. Reagents and conditions: a) PhMe, reflux, 19 h, 74%; b) LiBr, NaBH4, TH...
Scheme 2: Preparation of 7. Reagents and conditions: a) TsCl, Et3N, DMAP, MeCN, rt → reflux, 3.5 h, 82%; b) (...
Scheme 3: Homo and cross-coupling reactions of 6 or 7 afford BPTTFs and MPTTFs, respectively. Reagents and co...
Scheme 4: Deprotection and methylation of cyanoethyl-protected thiol moieties on MPTTFs as reported by Jeppes...
Scheme 5: Deprotection and alkylation of cyanoethyl-protected thiol moieties on MPTTFs using CsOH·H2O or DBU....
Scheme 6: Deprotection and N-arylation of tosylated MPTTFs. Reagents and conditions: a) NaOMe, THF, MeOH, ref...
Scheme 7: Deprotection and N,N-diarylation of tosylated BPTTFs. Reagents and conditions: a) NaOMe, THF, MeOH,...
Synthesis of isoprenoid bisphosphonate ethers through C–P bond formations: Potential inhibitors of geranylgeranyl diphosphate synthase
- Xiang Zhou,
- Jacqueline E. Reilly,
- Kathleen A. Loerch,
- Raymond J. Hohl and
- David F. Wiemer
Beilstein J. Org. Chem. 2014, 10, 1645–1650, doi:10.3762/bjoc.10.171
- parallel conditions went unrewarded, which might be attributed to the lower reactivity of this alkyl bromide vis-à-vis the allylic geranyl and prenyl bromides used above. Alternate strategies for preparation of compound 25 have not yet been explored, pending determination of the biological activity of the
Graphical Abstract
Figure 1: Inhibitors of isoprene biosynthesis.
Figure 2: Biosynthesis of geranylgeranyl diphosphate.
Figure 3: A known inhibitor of GGDPS (5) and a new analogue (6).
Scheme 1: Synthesis of bisphosphonate ethers 6 and 11.
Scheme 2: Synthesis of prenyl/geranyl bisphosphonate isomers.
Scheme 3: Synthesis of citronellyl bisphosphonates.
One-pot synthesis of cyanohydrin derivatives from alkyl bromides via incorporation of two one-carbon components by consecutive radical/ionic reactions
- Shuhei Sumino,
- Akira Fusano,
- Hiroyuki Okai,
- Takahide Fukuyama and
- Ilhyong Ryu
Beilstein J. Org. Chem. 2014, 10, 150–154, doi:10.3762/bjoc.10.12
- bromides and nucleophilic addition of a cyanide ion was investigated, which gave moderate to good yields of cyanohydrin derivatives in one-pot. Keywords: alkyl bromide; carbon monoxide; cyanohydrin; ethyl cyanoformate; multicomponent; radical reaction; Introduction Radical carbonylation reactions have
Graphical Abstract
Scheme 1: Sequential radical formylation and derivatization.
Scheme 2: Examination of cyanide source.
One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction
- Diego Carnaroglio,
- Katia Martina,
- Giovanni Palmisano,
- Andrea Penoni,
- Claudia Domini and
- Giancarlo Cravotto
Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274
- reaction was repeated in a bigger scale (80 mL) in a Parr reactor at the same pressure. Despite the good conversion (about 93%), the product purity was slightly lower than that of the MW-assisted reaction. To expand the scope of this method, a sequential one-pot synthesis from the alkyl bromide to the urea
- reaction of alkyl bromide with NaN3 can also be performed in MeCN. NaN3 is insoluble in MeCN at room temperature (<0.005 g/100 mL), but its solubility increases at higher temperatures. Furthermore, NaBr generated during the nucleophilic substitution is insoluble and can be removed by filtration as can the
- under vacuum. Representative “multi-pot” procedure for the synthesis of urea derivatives: NaN3 (0.477 mmol) was added to a solution of alkyl bromide (0.318 mmol) in MeCN (1.5 mL). The mixture was irradiated by MW for 3 h at 95 °C (average power 240 W) under N2 (2 bar) and magnetic stirring. After the
The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow
- Kimberley A. Roper,
- Malcolm B. Berry and
- Steven V. Ley
Beilstein J. Org. Chem. 2013, 9, 1781–1790, doi:10.3762/bjoc.9.207
- -dibromoolefination active species through multiple Ramirez reactions, the monolith could then be used to successfully perform the Appel reaction in flow. Approximately 0.55 mmol of alcohol could be transformed into the corresponding alkyl bromide following approximately 0.80 mmol of successful gem-dibromoolefination
Graphical Abstract
Scheme 1: Formation of gem-dibromoolefin 3 from the reaction of carbon tetrabromide and triphenylphosphine as...
Scheme 2: Formation of the triphenylphosphine monoliths.
Figure 1: a. An unfunctionalised triphenylphosphine monolith; b. Monolith after functionalisation with carbon...
Scheme 3: Functionalising the triphenylphosphine monolith to give the active Ramirez monolith using carbon te...
Scheme 4: Flow synthesis of gem-dibromoolefins using the functionalised triphenylphosphine monolith.
Scheme 5: Flow synthesis of bromides from the corresponding alcohols using the functionalised triphenylphosph...
Scheme 6: Mechanisms for the Ramirez and Appel reactions [41,59].
Copper-catalyzed CuAAC/intramolecular C–H arylation sequence: Synthesis of annulated 1,2,3-triazoles
- Rajkumar Jeyachandran,
- Harish Kumar Potukuchi and
- Lutz Ackermann
Beilstein J. Org. Chem. 2012, 8, 1771–1777, doi:10.3762/bjoc.8.202
- apparatus SMP3, Barlworld Scientific; values are uncorrected. General procedure for the synthesis of triazoles 4 NaN3 (1.05 equiv), CuI (10 mol %), LiOt-Bu (2.00 equiv), alkyne 1 (1.00 equiv) and alkyl bromide 2 (1.00 equiv) were dissolved in DMF (3.0 mL) and stirred at 80 °C for 20 h. Then, H2O (50 mL) was
Graphical Abstract
Scheme 1: Copper-catalyzed step-economical C–H arylation-based cascade reaction.
Scheme 2: Copper-catalyzed sequential catalysis with alkyne 1a.
Scheme 3: Copper-catalyzed reaction sequence using alkyl bromides 2. General reaction conditions: 1 (1.00 mmo...
Scheme 4: Nonsequential cascade synthesis of fully substituted triazoles 4. General reaction conditions: 1 (1...
Scheme 5: Copper-catalyzed one-pot twofold C–H/N–H arylation with azoles 5. aReaction performed at 120 °C.
The application of a monolithic triphenylphosphine reagent for conducting Appel reactions in flow microreactors
- Kimberley A. Roper,
- Heiko Lange,
- Anastasios Polyzos,
- Malcolm B. Berry,
- Ian R. Baxendale and
- Steven V. Ley
Beilstein J. Org. Chem. 2011, 7, 1648–1655, doi:10.3762/bjoc.7.194
- application of this monolith to the transformation of an alkyl alcohol into the corresponding alkyl bromide by using carbon tetrabromide in the Appel reaction. In the 1960s Ramirez and co-workers reported the formation of a phosphine–methylene species when triphenylphosphine was mixed with carbon tetrabromide
Graphical Abstract
Scheme 1: The two proposed mechanistic pathways for the Appel reaction.
Scheme 2: Functionalisation of the triphenylphosphine monolith by using carbon tetrabromide in a recycling pr...
Figure 1: a. Unfunctionalised triphenylphosphine monolith; b. Monolith after fuctionalisation with carbon tet...
Scheme 3: Flow synthesis of bromides from alcohols by using the functionalised triphenylphosphine monolith.
Figure 2: Linear decrease of the brown decolourisation.
Metathesis access to monocyclic iminocyclitol-based therapeutic agents
- Ileana Dragutan,
- Valerian Dragutan,
- Carmen Mitan,
- Hermanus C.M. Vosloo,
- Lionel Delaude and
- Albert Demonceau
Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81
- produce the (+)-DMDP (49) and (−)-bulgecinine (50) (Scheme 8). The starting point in the synthesis of (+)-broussonetine G, 53, was the same annulated oxazolone 48 which, after conversion into the Weinreb amide 51, was coupled with the alkyl bromide substituted spiro compound 52 (Scheme 9). In fact, the
Graphical Abstract
Scheme 1: Well-defined Mo- and Ru-alkylidene metathesis catalysts.
Scheme 2: Representative pyrrolidine-based iminocyclitols.
Scheme 3: Synthesis of (±)-(2R*,3R*,4S*)-2-hydroxymethylpyrrolidin-3,4-diol (18), (±)-2-hydroxymethylpyrrolid...
Scheme 4: Synthesis of enantiopure iminocyclitol (−)-(2S,3R,4S,5S)-2,5-dihydroxymethylpyrrolidin-3,4-diol (23...
Scheme 5: Synthesis of 1,4-dideoxy-1,4-imino-D-allitol (29) and formal synthesis of (2S,3R,4S)-3,4-dihydroxyp...
Scheme 6: Synthesis of iminocyclitols 35 and 36.
Scheme 7: Total synthesis of iminocyclitols 40 and 44.
Scheme 8: Synthesis of 2,5-dideoxy-2,5-imino-D-mannitol [(+)-DMDP] (49) and (−)-bulgecinine (50).
Scheme 9: Synthesis of (+)-broussonetine G (53).
Scheme 10: Structural features of broussonetines 54.
Scheme 11: Synthesis of broussonetines by cross-metathesis.
Scheme 12: Representative piperidine-based iminocyclitols.
Scheme 13: Total synthesis of 1-deoxynojirimycin (62) and 1-deoxyaltronojirimycin (65).
Scheme 14: Synthesis by RCM of 1-deoxymannonojirimycin (63) and 1-deoxyallonojirimycin (66).
Scheme 15: Total synthesis of (+)-1-deoxynojirimycin (62).
Scheme 16: Synthesis of ent-1,6-dideoxynojirimycin (83) and 5-amino-1,5,6-trideoxyaltrose (84).
Scheme 17: Synthesis of 1-deoxygalactonojirimycin (64), 1-deoxygulonojirimycin (91) and 1-deoxyidonojirimycin (...
Scheme 18: Synthesis of L-1-deoxyaltronojirimycin (96).
Scheme 19: Synthesis of 1-deoxymannonojirimycin (63) and 1-deoxyaltronojirimycin (65).
Scheme 20: Synthesis of 5-des(hydroxymethyl)-1-deoxymannonojirimycin (111) and 5-des(hydroxymethyl)-1-deoxynoj...
Scheme 21: Synthesis of D-1-deoxygulonojirimycin (91) and L-1-deoxyallonojirimycin (122).
Scheme 22: Total synthesis of fagomine (129), 3-epi-fagomine (126) and 3,4-di-epi-fagomine (130).
Scheme 23: Total synthesis of (+)-adenophorine (135).
Scheme 24: Total synthesis of (+)-5-deoxyadenophorine (138) and analogues 142–145.
Scheme 25: Synthesis by RCM of 1,6-dideoxy-1,6-iminoheptitols 148 and 149.
Scheme 26: Synthesis by RCM of oxazolidinyl azacycles 152 and 154.
Scheme 27: Representative azepane-based iminocyclitols.
Scheme 28: Synthesis of hydroxymethyl-1-(4-methylphenylsulfonyl)azepane 3,4,5-triol (169).
Scheme 29: Synthesis by RCM of tetrahydropyridin-3-ol 171 and tetrahydroazepin-3-ol 173.
EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides
- Giorgio Bencivenni,
- Riccardo Cesari,
- Daniele Nanni,
- Hassane El Mkami and
- John C. Walton
Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84
- sample was analysed by EPR spectroscopy at several different temperatures. Products analysis was performed as above. Ethyl 5-azidopentanoate (9) [48] was prepared by treatment of the corresponding alkyl bromide with sodium azide in DMSO [49]; IR (νmax, CHCl3), 1718 (CO) and 2092 (N3) cm−1; 1H NMR (400
Graphical Abstract
Scheme 1: Organic azides studied.
Scheme 2: Reaction of 4-substituted-phenyl azides with GaCl3.
Figure 1: EPR spectra after treatment of azide 2 with MCl3. (a) AlCl3 in DCM; 1st derivative spectrum at 300 ...
Figure 2: EPR spectrum after treatment of tetra-deuterated azide 3 with AlCl3. Top: 2nd derivative spectrum a...
Figure 3: EPR spectra after treatment of azide 1 with AlCl3. (a) 1st derivative spectrum in DCM at 280 K. (b)...
Figure 4: EPR spectra after GaCl3 and InCl3 reactions of azide 6. (a) 1st derivative spectrum from 6 and GaCl3...
Scheme 3: Dimer and trimer radical cations.
Figure 5: EPR spectra after GaCl3- and InCl3-promoted reactions of 2-methoxyphenyl azide 5. (a) 1st derivativ...
Figure 6: EPR spectra after In-, Ga- and Al-promoted reactions of azide 8. (a) intermediate from InCl3 treatm...
Figure 7: Experimental and simulated Davies ENDOR spectrum after the Ga-promoted reaction of azide 6 recorded...
Figure 8: DFT structures and SOMOs for dimer and trimer radical cations.
Scheme 4: Possible mechanism of formation of aromatic amines.
Scheme 5: Possible mechanism for dimer and trimer formation.
2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β2-amino acids
- Markus Nahrwold,
- Arvydas Stončius,
- Anna Penner,
- Beate Neumann,
- Hans-Georg Stammler and
- Norbert Sewald
Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43
- to the reaction mixture for an in situ conversion of the alkyl bromide to the alkyl iodide [48] did not increase reactivity. The alkylation reaction started to proceed only after warming the lithium enolate solution to −55 °C, but still remained incomplete after 20 h reaction time. By adding DMPU as
Graphical Abstract
Scheme 1: Selectively cleavable β2-amino acid precursors: Structures and reactivities of 2-tert-butyl-tetrahy...
Scheme 2: Cyclocondensation of Cbz-βAla-NH2 (3) and benzaldehyde. a) [p-TsOH], toluene, reflux, Dean–Stark tr...
Scheme 3: Protection and deprotection of 4. a) Boc2O, DMAP, CH3CN, 16 h, rt; b) 1. n-BuLi, THF, −78 °C, 30 mi...
Scheme 4: Synthesis of enantiopure 2-phenyl-tetrahydropyrimidine-4(1H)-ones. a) PhCH(OMe)2, BF3·Et2O (6.0 equ...
Figure 1: X-ray crystal structure of 10 [44].
Scheme 5: Diastereoselective alkylation of 5.
Figure 2: Comparison of coupling constants (C5–C6-ABX system) within the 1H-NMR spectra of literature known c...
Figure 3: Supposed enolate conformations.
Scheme 6: Selective ring opening of the heterocycle 11d and isolation of orthogonally protected β2-homoaspart...
