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Search for "kinetic control" in Full Text gives 50 result(s) in Beilstein Journal of Organic Chemistry.
Switchable molecular tweezers: design and applications
- Pablo Msellem,
- Maksym Dekthiarenko,
- Nihal Hadj Seyd and
- Guillaume Vives
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
Graphical Abstract
Figure 1: Principle of switchable molecular tweezers.
Figure 2: Principle of pH-switchable molecular tweezers 1 [19].
Figure 3: a) pH-Switchable tweezers 2 substituted with alkyl chains as switchable lipids. b) Schematic depict...
Figure 4: Modification of spectral properties of 3 by controlled induction of Pt–Pt interactions.
Figure 5: Conformational switching of di(hydroxyphenyl)pyrimidine-based tweezer 4 upon alkylation or fluoride...
Figure 6: Hydrazone-based pH-responsive tweezers 5 for mesogenic modulation.
Figure 7: pH-Switchable molecular tweezers 6 bearing acridinium moieties.
Figure 8: a) Terpyridine and pyridine-hydrazone-pyridine analogs molecular tweezers and b) extended pyridine ...
Figure 9: Terpyridine-based molecular tweezers with M–salphen arms and their field of application. Figure 9 was adapt...
Figure 10: a) Terpyridine-based molecular tweezers for diphosphate recognition [48]; b) bishelicene chiroptical te...
Figure 11: Terpyridine-based molecular tweezers with allosteric cooperative binding.
Figure 12: Terpyridine-based molecular tweezers presenting closed by default conformation.
Figure 13: Pyridine-pyrimidine-pyridine-based molecular tweezers.
Figure 14: Coordination-responsive molecular tweezers based on nitrogen-containing ligands.
Figure 15: Molecular tweezers exploiting the remote bipyridine or pyridine binding to trigger the conformation...
Figure 16: Bipyridine-based molecular tweezers exploiting the direct s-trans to s-cis-switching for a) anion b...
Figure 17: a) Podand-based molecular tweezers [66,67]. b) Application of tweezers 32 for the catalytic allosteric reg...
Figure 18: Anion-triggered molecular tweezers based on calix[4]pyrrole.
Figure 19: Anion-triggered molecular tweezers.
Figure 20: a) Principle of the weak link approach (WLA) developed by Mirkin and its application to b) symmetri...
Figure 21: Molecular tweezers as allosteric catalyst in asymmetric epoxide opening [80].
Figure 22: Allosteric regulation of catalytic activity in ring-opening polymerization with double tweezers 41.
Figure 23: a) Conformational switching of 42 by intramolecular –S–S– bridge formation. b) Shift of conformatio...
Figure 24: a) Redox-active glycoluril-TTF tweezers 44. b) Mechanism of stepwise oxidation of said tweezers wit...
Figure 25: Mechanism of formation of the mixed-valence dimers of tweezers 45.
Figure 26: Mechanism of carbohydrate liberation upon redox-mediated conformation switching of 46.
Figure 27: a) The encapsulation properties of 47 as well as the DCTNF release process from its host–guest comp...
Figure 28: Redox-active bipyridinium-based tweezers. a) With a ferrocenyl hinge 49, b) with a propyl hinge 50 ...
Figure 29: Redox-active calix[4]arene porphyrin molecular tweezers.
Figure 30: a) Mechanism of the three orthogonal stimuli. b) Cubic scheme showing the eight different states of ...
Figure 31: Redox-controlled molecular gripper based on a diquinone resorcin[4]arene.
Figure 32: a) Shinkai's butterfly tweezers and their different host–guest properties depending on the isomer. ...
Figure 33: Cyclam-tethered tweezers and their different host–guest complexes depending on their configuration.
Figure 34: Azobenzene-based catalytic tweezers.
Figure 35: Photoswitchable PIEZO channel mimic.
Figure 36: Stilbene-based porphyrin tweezers for fullerene recognition.
Figure 37: Stiff-stilbene-based tweezers with urea or thiourea functional units for a) anion binding, b) anion...
Figure 38: Feringa’s photoswitchable organocatalyst (a) and different catalyzed reactions with that system (b)....
Figure 39: a) Irie and Takeshita’s thioindigo-based molecular tweezers. b) Family of hemithioindigo-based mole...
Figure 40: Dithienylethylene crown ether-bearing molecular tweezers reported by Irie and co-workers.
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...
Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?
- Lukáš Marek,
- Jiří Váňa,
- Jan Svoboda and
- Jiří Hanusek
Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61
- MeCN undergoes a ring transformation [1][2] to give 2-phenyl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazole (17') (Scheme 7) under kinetic control, the analogous intermediary hydroxythiazole 7a (Scheme 3) does not decompose into analogous thiazole 7a' due to much worse nucleofugality of the leaving amine
Graphical Abstract
Scheme 1: Eschenmoser coupling reaction between 3-substituted oxindoles and thioamides.
Scheme 2: Possible reactions of α-haloketones, esters and amides with primary thioamides.
Figure 1: Studied α-bromoamides and α-bromolactams.
Scheme 3: Reaction of 4-bromo-1,1-dimethyl-1,4-dihydroisoquinolin-3(2H)-one (2b) with thiobenzamide and thioa...
Scheme 4: Reaction of 4-bromo-1,1-dimethyl-1,4-dihydroisoquinolin-3(2H)-one (2b) with 4’-substituted thiobenz...
Scheme 5: Reaction of 4-bromoisoquinoline-1,3(2H,4H)-dione (3) with thiobenzamide, thioacetamide, and thioben...
Scheme 6: Reaction of N-phenyl- and N-methyl-2-bromo(phenyl)acetamide (4a,b) with thiobenzamide in acetonitri...
Scheme 7: Transformation of salt 15 under kinetic and thermodynamic control conditions [1].
Figure 2: Comparison of energy profiles (relative Gibbs energies at 298 K in kJ·mol−1 for the ECR (right) and...
Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles
- Ekaterina A. Lystsova,
- Maksim V. Dmitriev,
- Andrey N. Maslivets and
- Ekaterina E. Khramtsova
Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46
- products 6a,b,e were formed (Scheme 10). These observations are in a full accordance with the studies of similar products of 5-oxa-FPDs II [33][53][54]. We assume compounds 5 to be products of the kinetic control of the reaction, and compounds 3, of the thermodynamic one. In addition, the formation of
Graphical Abstract
Figure 1: Biologically active PBTAs.
Scheme 1: Approaches to PBTAs via annulation of benzothiazoles.
Scheme 2: Approaches to PBTAs via annulation of o-aminothiophenols.
Scheme 3: Approach to PBTAs via radical substitution reaction in 1-(2-bromophenyl)-5-(butylsulfanyl)pyrrolidi...
Scheme 4: Approach to PBTAs via intramolecular cyclizations of 1-(2-thiophenyl)pyrroles.
Scheme 5: A new approach to PBTAs via nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazin...
Figure 2: Electrophilic centers in FPDs.
Scheme 6: Reaction of APBTT 1a with methanol (2a).
Scheme 7: Derivatization of PBTA 3aa.
Scheme 8: Reaction of APBTTs 1a–h with alcohols 2a–c. Isolated yields are given; reaction scale: a mixture of ...
Scheme 9: Side-reaction of APBTTs 1 with alcohols 2.
Scheme 10: Transformations of compounds 5 in solutions.
Scheme 11: Reaction of APBTT 1a with benzylamine.
Scheme 12: Derivatization of PBTA 7a.
Scheme 13: Reaction of APBTTs 1a–h and benzylamine. Isolated yields are given; reaction scale: a mixture of 1 ...
Scheme 14: Reaction of APBTT 1a with an excess of benzylamine.
Scheme 15: Reaction of APBTT 1a with morpholine.
Scheme 16: Reaction of APBTT 1a with aniline (11a).
Scheme 17: Derivatization of PBTA 12aa.
Scheme 18: Reaction of APBTTs 1a–h and arylamines 11a–d. Isolated yields are given; reaction scale: a mixture ...
Scheme 19: Side-reaction of APBTT 1a with arylamine 11b.
Scheme 20: Reaction of APBTT 1a with compounds 16a–d.
Scheme 21: Formation of compounds 17 as an undesired process during the synthesis of APBTTs 1.
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
- level of stereoselectivity induction is important for the evaluation of the chiral templates efficiency. The estimation of the thermodynamically and kinetically controlled stereoselectivity is based on different approaches. The diastereomeric ratio of the products formed under kinetic control is related
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, ...
Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones
- Nguyen Tran Nguyen,
- Vo Viet Dai,
- Nguyen Ngoc Tri,
- Luc Van Meervelt,
- Nguyen Tien Trung and
- Wim Dehaen
Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118
- IS5 and finally forming product 10ab is the most preferred pathway, and even more favorable than both directions from 4a to yield 10ab-v2. Hence, the reaction routes to obtain 10ab-v2 are thermodynamically favorable, while yielding 10ab is under kinetic control. In order to better evaluate the
Graphical Abstract
Figure 1: Structure of naturally occurring and synthetic 2-pyrrolidone derivatives.
Figure 2: Structure of natural compounds containing a 1,5-dihydro-2H-pyrrol-2-one subunit.
Scheme 1: Synthesis of substituted 4-acetyl-3-hydroxy-3-pyrroline-2-ones 4 via three-component reaction.
Scheme 2: Proposed mechanistic path for the synthesis of substituted 4-acetyl-3-hydroxy-3-pyrroline-2-ones.
Scheme 3: Tautomerism of compounds 4a–c in DMSO.
Figure 3: View of the molecular structure of compound 10aa with atom labeling. Displacement ellipsoids are dr...
Figure 4: The PES of reaction for the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-dione 10ab enamine de...
Scheme 4: Reaction pathways from 4a, 4a’ to 10ab via IS5 in the gase phase.
Scheme 5: Reaction pathways from 4a to 10ab-v2 via IS3 in the gase phase.
Figure 5: The PES for the possible pathways (1), (2), (3), and (4) in ethanol solvent.
Figure 6: The optimized structures of some reactants, intermediates, transition states, and products in the p...
Understanding the competing pathways leading to hydropyrene and isoelisabethatriene
- Shani Zev,
- Marion Ringel,
- Ronja Driller,
- Bernhard Loll,
- Thomas Brück and
- Dan T. Major
Beilstein J. Org. Chem. 2022, 18, 972–978, doi:10.3762/bjoc.18.97
- . We show that there is a great thermodynamic preference for hydropyrene and hydropyrenol formation, and hence most likely in the synthesis of the isoelisabethatriene products kinetic control is at play. Keywords: diterpenes; enzyme mechanism; quantum mechanics; terpene synthases; thermodynamic and
- kinetic control; Introduction Terpenes constitute a ubiquitous class of natural molecules that are synthesized by terpene synthases (TPS). TPS generate a plethora of terpenes employing rich carbocation chemistry from a very limited number of substrates, known as geranyl pyrophosphate (GPP), farnesyl
- inherent chemistry in these reactions and also points to some understanding of the possible thermodynamic and kinetic control in the enzyme. Results Reaction mechanism To better understand the HP and IE reaction pathways, we performed quantum mechanics (QM) calculations using density functional theory (DFT
Graphical Abstract
Figure 1: Summary of yields of HP and IE products in hydropyrene synthase.
Scheme 1: Proposed mechanism for HP and IE routes.
Figure 2: Free energy profile of hydropyrene cation (a), and IE cation (b) formation in the gas phase. The fr...
Figure 3: Structures of intermediates C‘ and C. The distance between the double bond and the cation in interm...
Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple
- Alexander S. Filatov,
- Olesya V. Khoroshilova,
- Anna G. Larina,
- Vitali M. Boitsov and
- Alexander V. Stepakov
Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77
- revealed that the cycloaddition reactions are under kinetic control and belong to the class of inverse electron demand 1,3-DC reactions. We believe that the outcome of this work will serve as a basis for developing synthetic approaches to other bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via
Graphical Abstract
Scheme 1: Early studies concerning cyclopropene cycloadditions to azomethine ylides and cycloaddition reactio...
Scheme 2: The pilot experiment aimed at studying the cycloaddition reaction between the protonated form of Ru...
Scheme 3: Synthesis of meso-3'-azadispiro[indene-2,2'-bicyclo[3.1.0]hexane-4',2''-indene] derivatives 3b–g vi...
Figure 1: ORTEP representation of the molecular structure of 3e.
Scheme 4: The reaction of protonated Ruhemann's purple (1) with 3-methyl-3-phenylcyclopropene (2j).
Scheme 5: Attempts to carry out the cycloaddition reactions between 3,3-disubstituted cyclopropenes 2k,l and ...
Scheme 6: The reactions of protonated Ruhemann's purple (1) with unstable cyclopropenes 2m–p.
Scheme 7: The acid–base reaction of Ruhemann's purple with hydrochloric acid and relative Gibbs free energy c...
Scheme 8: Plausible mechanism of the 1,3-DC reaction of protonated Ruhemann's purple (1) with 3-methyl-3-phen...
Scheme 9: Plausible mechanism of the 1,3-DC reaction of protonated Ruhemann's purple (1) with 1-chloro-2-phen...
Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis
- Prodip Howlader and
- Michael Schmittel
Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62
- heteroleptic aggregates are quite different. While in the former often a step-by-step attachment of the different ligands to the metal centers under kinetic control is dominating, the formation of dynamic aggregates relies on effective self-sorting protocols under thermodynamic control [24]. In its initial
Graphical Abstract
Figure 1: Butterfly 1 (Figure was reprinted with permission from [45]. Copyright 2012 American Chemical Society. ...
Figure 2: Synthesis of the three-component heteroleptic molecular boat 8 and its use as a catalyst for the Kn...
Figure 3: Synthesis of the two-component triangle 14 and three-component heteroleptic prism 15 [59]. Figure was a...
Figure 4: Catalytic Michael addition reaction using the urea-decorated molecular prism 15 [59].
Figure 5: Self-assembly of two-component tetragonal prismatic architectures with different cavity size. Figur...
Figure 6: Construction of artificial LHS using rhodamine B as an acceptor and 24b as donor generating a photo...
Figure 7: Synthesis of supramolecular spheres with varying [AuCl] concentration inside the cavity. Figure was...
Figure 8: Hydroalkoxylation reaction of γ-allenol 34 in the presence of [AuCl]-encapsulated molecular spheres ...
Figure 9: Two-component heteroleptic triangles of different size containing a BINOL functionality. Figure was...
Figure 10: Asymmetric conjugate addition of chalcone 42 with trans-styrylboronic acid (43) catalyzed by BINOL-...
Figure 11: Encapsulation of monophosphoramidite-Rh(I) catalyst into a heteroleptic tetragonal prismatic cage 47...
Figure 12: (a) Representations of the basic HETPYP, HETPHEN, and HETTAP complex motifs. (b) The three-componen...
Figure 13: Two representative four-component rotors, with a (top) two-arm stator and (bottom) a four-arm stato...
Figure 14: Four-component rotors with a monohead rotator. Figure was adapted with permission from [94]. Copyright ...
Figure 15: (left) Click reaction catalyzed by rotors [Cu2(55)(60)(X)]2+. (right) Yield as a function of the ro...
Figure 16: A supramolecular AND gate. a) In truth table state (0,0) two nanoswitches serve as the receptor ens...
Figure 17: Two supramolecular double rotors (each has two rotational axes) and reference complex [Cu(78)]+ for...
Figure 18: The slider-on-deck system (82•X) (X = 83, 84, or 85). Figure is from [98] and was reprinted from the jo...
Figure 19: Catalysis of a conjugated addition reaction in the presence of the slider-on-deck system (82•X) (X ...
Figure 20: A rotating catalyst builds a catalytic machinery. For catalysis of the catalytic machinery, see Figure 21. F...
Figure 21: Catalytic machinery. Figure was adapted from [100] (“Evolution of catalytic machinery: three-component n...
Figure 22: An information system based on (re)shuffling components between supramolecular structures [99]. Figure ...
Figure 23: Switching between dimeric heteroleptic and homoleptic complex for OFF/ON catalytic formation of rot...
Figure 24: A chemically fueled catalytic system [112]. Figure was adapted from [112]. Copyright 2021 American Chemical S...
Figure 25: (Top) Operation of a fuel acid. (Bottom) Knoevenagel addition [112].
Figure 26: Development of the yield of Knoevenagel product 118 in a fueled system [112]. Figure was reprinted with ...
Figure 27: Weak-link strategy to increased catalytic activity in epoxide opening [119]. Figure was adapted from [24]. C...
Figure 28: A ON/OFF polymerization switch based on the weak-link approach [118]. Figure was reprinted with permissi...
Figure 29: A weak-link switch turning ON/OFF a Diels–Alder reaction [132]. Figure was reprinted with permission fro...
Figure 30: A catalyst duo allowing selective activation of one of two catalytic acylation reactions [133] upon subs...
Figure 31: A four-state switchable nanoswitch (redrawn from [134]).
Figure 32: Sequential catalysis as regulated by nanoswitch 138 and catalyst 139 in the presence of metal ions ...
Figure 33: Remote control of ON/OFF catalysis administrated by two nanoswitches through ion signaling (redrawn...
BINOL as a chiral element in mechanically interlocked molecules
- Matthias Krajnc and
- Jochen Niemeyer
Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53
- is formed preferentially under kinetic control (er = 67:33, total yield 23%). Interestingly, employing (R)-15 together with (rac)-19 gave a significantly lower diastereoselectivity (er = 56:44), albeit at slightly increased yield (33%). Similarly, the reaction of the chiral isomannide-based
Graphical Abstract
Figure 1: Molecular structures of (R)-BINOL (left) and (S)-BINOL (right).
Figure 2: Synthesis of Sauvage´s [2]catenanes (S,S)-5 and (S,S)-6 containing two BINOL units by the passive m...
Figure 3: Synthesis of Saito´s [2]rotaxane (R)-10 from a BINOL-based macrocycle by the active metal template ...
Figure 4: Synthesis of Stoddart´s [2]rotaxane (rac)-14 by an ammonium crown ether template.
Figure 5: Synthesis of Stoddart´s BINOL-containing [2]catenanes 18/20/22/24 by π–π recognition.
Figure 6: Synthesis of Takata´s rotaxanes featuring chiral centers on the axle: a) rotaxane (R,R,R/S)-27 obta...
Figure 7: Takata´s chiral polyacetylenes 32/33 featuring BINOL-based [2]rotaxane side chains.
Figure 8: Synthesis of Takata´s chiral thiazolium [2]rotaxanes (R)-35a/b and (R)-38.
Figure 9: Results for the asymmetric benzoin condensation of benzaldehyde (39) with catalysts (R)-35a/b and (R...
Figure 10: Synthesis of Takata´s pyridine-based [2]rotaxane (R)-42.
Figure 11: The asymmetric desymmetrization reaction of meso-1,2-diols with rotaxane (R)-42.
Figure 12: Synthesis of Niemeyer´s axially chiral [2]catenane (S,S)-47.
Figure 13: Results for the enantioselective transfer hydrogenation of 2-phenylquinoline with catalysts (S,S)-47...
Figure 14: Synthesis of Niemeyer´s chiral [2]rotaxanes (S)-56/57.
Figure 15: Results for the enantioselective Michael addition with different rotaxane catalysts (S)-56a/56b/57a/...
Figure 16: Synthesis of Beer´s [2]rotaxanes 64a/b for anion recognition.
Figure 17: Association constants of different anions (used as the Bu4N+ salts) to the [2]rotaxanes (S)-64a/b a...
Figure 18: Synthesis of Beer´s [3]rotaxane (S)-68.
Figure 19: Association constants of different anions (used as the Bu4N+-salts) to the [2]rotaxane (S)-68 and a...
Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances
- Thiago S. Silva and
- Fernando Coelho
Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112
- -cyclization products was attributed to the better overlap between the π-orbital of the enolic carbon atom and the π*-orbital of the complexed olefin terminal carbon. This suggests that, in these cases, the 6-endo-trig cyclizations are under kinetic control. The substrate generality in the methodology
Graphical Abstract
Figure 1: Some examples of natural products and drugs containing quaternary carbon centers.
Scheme 1: Simplified mechanism for olefin hydrofunctionalization using an electrophilic transition metal as a...
Scheme 2: Selected examples of quaternary carbon centers formed by the intramolecular hydroalkylation of β-di...
Scheme 3: Control experiments and the proposed mechanism for the Pd(II)-catalyzed intermolecular hydroalkylat...
Scheme 4: Intermolecular olefin hydroalkylation of less reactive ketones under Pd(II) catalysis using HCl as ...
Scheme 5: A) Selected examples of Pd(II)-mediated quaternary carbon center synthesis by intermolecular hydroa...
Scheme 6: Selected examples of quaternary carbon center synthesis by gold(III) catalysis. This is the first r...
Scheme 7: Selected examples of inter- (A) and intramolecular (B) olefin hydroalkylations promoted by a silver...
Scheme 8: A) Intermolecular hydroalkylation of N-alkenyl β-ketoamides under Au(I) catalysis in the synthesis ...
Scheme 9: Asymmetric pyrrolidine synthesis through intramolecular hydroalkylation of α-substituted N-alkenyl ...
Scheme 10: Proposed mechanism for the chiral gold(I) complex promotion of the intermolecular olefin hydroalkyl...
Scheme 11: Selected examples of carbon quaternary center synthesis by gold and evidence of catalytic system pa...
Scheme 12: Synthesis of a spiro compound via an aza-Michael addition/olefin hydroalkylation cascade promoted b...
Scheme 13: A selected example of quaternary carbon center synthesis using an Fe(III) salt as a catalyst for th...
Scheme 14: Intermolecular hydroalkylation catalyzed by a cationic iridium complex (Fuji (2019) [47]).
Scheme 15: Generic example of an olefin hydrofunctionalization via MHAT (Shenvi (2016) [51]).
Scheme 16: The first examples of olefin hydrofunctionalization run under neutral conditions (Mukaiyama (1989) [56]...
Scheme 17: A) Aryl olefin dimerization catalyzed by vitamin B12 and triggered by HAT. B) Control experiment to...
Scheme 18: Generic example of MHAT diolefin cycloisomerization and possible competitive pathways. Shenvi (2014...
Scheme 19: Selected examples of the MHAT-promoted cycloisomerization reaction of unactivated olefins leading t...
Scheme 20: Regioselective carbocyclizations promoted by an MHAT process (Norton (2008) [76]).
Scheme 21: Selected examples of quaternary carbon centers synthetized via intra- (A) and intermolecular (B) MH...
Scheme 22: A) Proposed mechanism for the Fe(III)/PhSiH3-promoted radical conjugate addition between olefins an...
Scheme 23: Examples of cascade reactions triggered by HAT for the construction of trans-decalin backbone uniti...
Scheme 24: A) Selected examples of the MHAT-promoted radical conjugate addition between olefins and p-quinone ...
Scheme 25: A) MHAT triggered radical conjugate addition/E1cB/lactonization (in some cases) cascade between ole...
Scheme 26: A) Spirocyclization promoted by Fe(III) hydroalkylation of unactivated olefins. B) Simplified mecha...
Scheme 27: A) Selected examples of the construction of a carbon quaternary center by the MHAT-triggered radica...
Scheme 28: Hydromethylation of unactivated olefins under iron-mediated MHAT (Baran (2015) [95]).
Scheme 29: The hydroalkylation of unactivated olefins via iron-mediated reductive coupling with hydrazones (Br...
Scheme 30: Selected examples of the Co(II)-catalyzed bicyclization of dialkenylarenes through the olefin hydro...
Scheme 31: Proposed mechanism for the bicyclization of dialkenylarenes triggered by a MHAT process (Vanderwal ...
Scheme 32: Enantioconvergent cross-coupling between olefins and tertiary halides (Fu (2018) [108]).
Scheme 33: Proposed mechanism for the Ni-catalyzed cross-coupling reaction between olefins and tertiary halide...
Scheme 34: Proposed catalytic cycles for a MHAT/Ni cross-coupling reaction between olefins and halides (Shenvi...
Scheme 35: Selected examples of the hydroalkylation of olefins by a dual catalytic Mn/Ni system (Shenvi (2019) ...
Scheme 36: A) Selected examples of quaternary carbon center synthesis by reductive atom transfer; TBC: 4-tert-...
Scheme 37: A) Selected examples of quaternary carbon centers synthetized by radical addition to unactivated ol...
Scheme 38: A) Selected examples of organophotocatalysis-mediated radical polyene cyclization via a PET process...
Scheme 39: A) Sc(OTf)3-mediated carbocyclization approach for the synthesis of vicinal quaternary carbon cente...
Scheme 40: Scope of the Lewis acid-catalyzed methallylation of electron-rich styrenes. Method A: B(C6F5)3 (5.0...
Scheme 41: The proposed mechanism for styrene methallylation (Oestreich (2019) [123]).
A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries
- Guido Gambacorta,
- James S. Sharley and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes
- Savva A. Ponomarev,
- Roman V. Larkovich,
- Alexander S. Aldoshin,
- Andrey A. Tabolin,
- Sema L. Ioffe,
- Jonathan Groß,
- Till Opatz and
- Valentine G. Nenajdenko
Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27
- proceed under the kinetic control since the isomer ratio remained constant throughout the reaction course regardless of the temperature (Table 1). The total effective pseudo-first order rate constants k* were obtained by plotting the experimental values of ln(c0/c) versus time with good correlations
Graphical Abstract
Scheme 1: Scope of the nitrostyrenes 1 in the Diels–Alder reaction with CPD (dr = exo:endo).
Figure 1: The structure assignment of norbornenes 2 by 1H (a) and NOE (b) NMR spectroscopy.
Figure 2: 13C NMR spectrum of the mixture of exo- and endo-isomers of norbornene 2l.
Figure 3: The predicted reaction pathway for the Diels–Alder reaction of nitrostyrene 1h with CPD is displaye...
Scheme 2: The Diels–Alder reaction of nitrostyrene 1h with spiro[2.4]hepta-4,6-diene.
Scheme 3: Diels–Alder reaction of nitrostyrenes 1 with CHD (dr = exo:endo). (а) Reaction under microwave acti...
Scheme 4: Kinetic study of reactions of 1h with CPD and CHD.
Figure 4: Kinetic curves for the reactions of nitrostyrene 1h with CPD (50–130 °C) and CHD at 110 °C.
Scheme 5: The Diels–Alder reaction of the nitrostyrene 1h with 1-methoxy-1,3-cyclohexadiene.
Scheme 6: Selected chemical transformations of norbornenes 2 (dr = exo:endo).
Pentannulation of N-heterocycles by a tandem gold-catalyzed [3,3]-rearrangement/Nazarov reaction of propargyl ester derivatives: a computational study on the crucial role of the nitrogen atom
- Giovanna Zanella,
- Martina Petrović,
- Dina Scarpi,
- Ernesto G. Occhiato and
- Enrique Gómez-Bengoa
Beilstein J. Org. Chem. 2020, 16, 3059–3068, doi:10.3762/bjoc.16.255
- ). Thus, under kinetic control, the reaction would lead to the formation of XII. However, as will be commented on later in the discussion, the experimental results clearly show the sole formation of compound 15 (Table 1), which arises from hydrolysis of an intermediate related to the complex XV. Thus, we
Graphical Abstract
Figure 1: Tandem acetate rearrangement/Nazarov cyclization of different substrates.
Figure 2: DFT-computed energy profile of the tandem Au(I)-catalyzed [3,3]-rearrangement/Nazarov reaction of 3...
Figure 3: DFT-computed energy profile of the tandem Au(I)-catalyzed [3,3]-rearrangement/Nazarov reaction of 2...
Figure 4: Computed comparison of the NBO charges of 2- and 3-substituted substrates.
Figure 5: Single-step transformation of IV to IX.
Figure 6: Triflate-promoted hydrogen abstraction and protodeauration with HOTf.
Figure 7: Triflate-mediated abstraction of the hydrogen atom Ha and protodeauration.
Scheme 1: Synthesis of the enynyl acetate starting material 14.
Scheme 2: Synthesis and cyclization of enynyl acetate 20.
Influence of per-O-sulfation upon the conformational behaviour of common furanosides
- Alexey G. Gerbst,
- Vadim B. Krylov,
- Dmitry A. Argunov,
- Maksim I. Petruk,
- Arsenii S. Solovev,
- Andrey S. Dmitrenok and
- Nikolay E. Nifantiev
Beilstein J. Org. Chem. 2019, 15, 685–694, doi:10.3762/bjoc.15.63
- -sulfated furanosides is reported. Results and Discussion Synthesis of per-O-sulfated furanosides Propyl α-D-mannofuranoside (1) was prepared from D-mannose and n-propanol via Fischer reaction using ion-exchange resin IR-120(H+) as acidic catalyst. The reaction was performed under kinetic control and was
Graphical Abstract
Scheme 1: Studied monosaccharides 1–3 and 1s–3s and their preparation.
Figure 1: The pseudo-rotation wheels showing different optimized structures of furanosides 1–3 and 1s–3s. The...
Figure 2: Schematic views of low energy conformers A–M. The minimal energy conformers are embedded in red fra...
Figure 3: Denotation of conformers obtained during rotation around C5–C6 bond.
Non-metal-templated approaches to bis(borane) derivatives of macrocyclic dibridgehead diphosphines via alkene metathesis
- Tobias Fiedler,
- Michał Barbasiewicz,
- Michael Stollenz and
- John A. Gladysz
Beilstein J. Org. Chem. 2018, 14, 2354–2365, doi:10.3762/bjoc.14.211
- the P(CH2)6CH=CH(CH2)6P tether. Importantly, all of these steps are presumed to be largely under kinetic control, consistent with experience with the types of metatheses in Scheme 1 [1][2][3][4][5][6][7][8][9][10][11][12][13][34]. Although the second route intuitively seems more favorable, after the
Graphical Abstract
Scheme 1: Syntheses of gyroscope like platinum and rhodium complexes and dibridgehead diphosphines derived th...
Scheme 2: Synthesis and alkene metathesis of the monophosphorus precursor 1·BH3.
Figure 1: The 13C{1H} NMR spectra (CDCl3, 100 MHz) of in,out-2·2BH3, (in,in/out,out)-2·2BH3, 6·2BH3, and the ...
Scheme 3: Synthesis of the diphosphorus precursor 11·2BH3.
Scheme 4: Truncated approaches to the diphosphorus precursor 11·2BH3 from 10.
Scheme 5: Alkene metathesis of the diphosphorus precursor 11·2BH3.
Scheme 6: Schematic comparison of the key alkene metathesis steps in Scheme 2 and Scheme 5.
Scheme 7: Steps that set the in,in/out,out vs in,out stereochemistry of 2·2BH3 in Scheme 2 and Scheme 5.
Scheme 8: Another non-metal-templated approach to dibridgehead diphosphorus compounds.
Scheme 9: Previously synthesized dibridgehead diphosphine diboranes.
Scheme 10: Alkene metathesis of the tetraalkenyldiphosphine diborane 19·2BH3.
Nanoreactors for green catalysis
- M. Teresa De Martino,
- Loai K. E. A. Abdelmohsen,
- Floris P. J. T. Rutjes and
- Jan C. M. van Hest
Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61
- worm-like micelles, form when 1/3 ≤ p ≤ 1/2. A typical micelle acquires a hydrophobic core that is able to accommodate hydrophobic catalysts, providing thermodynamic and kinetic control over chemical reactions [31]. Moreover, carrying out reactions in such a hydrophobic core leads to a concentration
Graphical Abstract
Figure 1: Assembly of catalyst-functionalized amphiphilic block copolymers into polymer micelles and vesicles...
Scheme 1: C–N bond formation under micellar catalyst conditions, no organic solvent involved. Adapted from re...
Scheme 2: Suzuki−Miyaura couplings with, or without, ppm Pd. Conditions: ArI 0.5 mmol 3a, Ar’B(OH)2 (0.75–1.0...
Figure 2: PQS (4a), PQS attached proline catalyst 4b. Adapted from reference [26]. Copyright 2012 American Chemic...
Figure 3: 3a) Schematic representation of a Pickering emulsion with the enzyme in the water phase (i), or wit...
Scheme 3: Cascade reaction with GOx and Myo. Adapted from reference [82].
Figure 4: Cross-linked polymersomes with Cu(OTf)2 catalyst. Reprinted with permission from [15].
Figure 5: Schematic representation of enzymatic polymerization in polymersomes. (A) CALB in the aqueous compa...
Figure 6: Representation of DSN-G0. Reprinted with permission from [100].
Figure 7: The multivalent esterase dendrimer 5 catalyzes the hydrolysis of 8-acyloxypyrene 1,3,6-trisulfonate...
Figure 8: Conversion of 4-NP in five successive cycles of reduction, catalyzed by Au@citrate, Au@PEG and Au@P...
Metal-mediated base pairs in parallel-stranded DNA
- Jens Müller
Beilstein J. Org. Chem. 2017, 13, 2671–2681, doi:10.3762/bjoc.13.265
- which a G–Pt(II)–G crosslink enforces a parallel strand orientation [70]. The preparation of this base pair was very distinct from the procedure commonly applied for the generation of Ag(I)- or Hg(II)-mediated base pairs [11], because Pt(II) reacts under kinetic control and has a high affinity for all
Graphical Abstract
Figure 1: Structure of a B-DNA duplex comprising a central C–Ag(I)–C base pair. This figure was created based...
Scheme 1: Hydrogen-bonding patterns of various reversed Watson–Crick base pairs. a) A:T; b) G:C (steric clash...
Scheme 2: Various hydrogen-bonding patterns. a) T:A:T and CH+:G:C base triples indicating how T:A and CH+:G H...
Scheme 3: Representation of a β-dA:α-dT base pair.
Scheme 4: Representation of mononuclear metal-mediated base pairs involving canonical pyrimidine nucleobases....
Scheme 5: Proposed base pairing patterns of FP–Ag(I)–FP, involving a) the Watson–Crick edge (antiparallel-str...
Scheme 6: Reaction pathway towards a parallel-stranded DNA duplex bearing a G–Pt(II)–G base pair. Adapted fro...
Scheme 7: Possible base pairing patterns of dinuclear Ag(I)-mediated base pairs. Base pairs within an antipar...
Scheme 8: Base pairing patterns of the dinuclear Ag(I)-mediated homo base pair of 1,N6-ethenoadenine (εA) wit...
Scheme 9: Additional metal-mediated base pairs involving 1,N6-ethenoadenine (εA). Base pairs within an antipa...
Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides
- Jihen Ati,
- Pierre Lafite and
- Richard Daniellou
Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180
- –enzyme intermediate can be attacked by another nucleophile than water (like an alcohol) to stereospecifically yield a new glycoside [60]. The reaction is now under kinetic control and the enzyme is named a transglycosidase. The rules that guide the balance between hydrolysis and transglycosylation are
Graphical Abstract
Figure 1: Mechanisms of O-GTs-catalysed glycosylation.
Figure 2: Desulfoglucosinolate biosynthesis by UGT74B1.
Figure 3: Examples of thiol-containing acceptors used in the chemo-enzymatic biosynthesis of S-glycosides cat...
Figure 4: Examples of C-glycosylated products biosynthesized by natural C-GT. Compounds showed are formed by ...
Figure 5: General mechanisms of the O-GHs-catalysed hydrolysis.
Figure 6: Neighbouring group participation mechanism of retaining the O-GHs-catalysed hydrolysis.
Figure 7: Mechanism of the thioligases.
Figure 8: Examples of thiol acceptors utilized with GHs.
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.
Framing major prebiotic transitions as stages of protocell development: three challenges for origins-of-life research
- Ben Shirt-Ediss,
- Sara Murillo-Sánchez and
- Kepa Ruiz-Mirazo
Beilstein J. Org. Chem. 2017, 13, 1388–1395, doi:10.3762/bjoc.13.135
- -specificity and functional integration achieved in a first protocellular scenario may be modest, but it is important that both kinetic control and spatial control mechanisms are included in the equation from the beginning, so that they can complement each other in their development. For an interesting bottom
- avenues in the field of systems chemistry [1][2]. For instance, although kinetic control mechanisms must play a central part in the explanation, dynamic kinetic stability [63] is not the answer (because replication is not all what matters for evolution, chemical or biological). It is probably too early to
Figure 1: Protocells as the main units of prebiotic evolution: three hypothetical stages of development towar...
How and why kinetics, thermodynamics, and chemistry induce the logic of biological evolution
- Addy Pross and
- Robert Pascal
Beilstein J. Org. Chem. 2017, 13, 665–674, doi:10.3762/bjoc.13.66
- -organisation of life, which, in turn, allows an assessment of semi-quantitative constraints on systems and environments from which life could evolve. Keywords: dynamic kinetic stability; kinetic control; origins of life; self-organisation; Introduction Although it is mostly understood in historic terms, the
- thermodynamic data. Indeed, there are many examples in which product formation is controlled by kinetics (reactions under kinetic control, corresponding to the situation in Figure 2), rather than by thermodynamic stabilities. In fact the presence of kinetic barriers is actually a requirement for the system to
- held far from equilibrium through the energy-fuelled supply of reactive units. Kinetic control. In many chemical reactions leading to different products, the final composition is determined by the height of the kinetic barriers corresponding to transition states (TS‡1 and TS‡2) rather than by the
Graphical Abstract
Figure 1: Self-assembly. (A) Macromolecular structures or patterns can form as the result of binding energy b...
Figure 2: Kinetic control. In many chemical reactions leading to different products, the final composition is...
Figure 3: Evolution of an autocatalytic network involving a parasite. R: resource; A: autocatalyst; B: predat...
Figure 4: Numerical simulation of the system of Figure 3 (k0 = 0.01 M min−1, k1 = 0.02 min−1, k2 = 0.4 M−1 min−1, k3 ...
Figure 5: The Raleigh–Bénard instability. Convection takes place in a liquid layer provided that the temperat...
Direct arylation catalysis with chloro[8-(dimesitylboryl)quinoline-κN]copper(I)
- Sem Raj Tamang and
- James D. Hoefelmeyer
Beilstein J. Org. Chem. 2016, 12, 2757–2762, doi:10.3762/bjoc.12.272
- substitution ratio is typical of substitutions on naphthalene under kinetic control that tend to favor the alpha C–H bonds due better resonance stabilization effects [53]. Importantly, we note the alpha protons are slightly more acidic than the beta protons [54]. The mechanism of Cu catalyzed coupling
Graphical Abstract
Scheme 1: Coordination of Cu(I) with the ambiphilic ligand 1 to form the catalyst 2.
Scheme 2: Proposed mechanism of direct arylation catalyzed by 2 (X = Cl/I; Ar = aryl).
Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction
- Ángel Cantín,
- M. Victoria Gomez and
- Antonio de la Hoz
Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208
- is reflected in the distribution products by a decrease of the endo-endo isomer (kinetic control product) jointed to an increase of the endo-exo (thermodynamic control product). Influence of catalyst surface We have seen that the DAR between cyclopentadiene and p-benzoquinone takes place thermally
Graphical Abstract
Scheme 1: Distribution of products in the Diels–Alder reaction between cyclopentadiene and p-benzoquinone.
Figure 1: Conversion in the DAR catalysed by silica Beta zeolites and Aerosil.
Figure 2: Effect of Lewis and Brønsted acid sites in the conversion (a) and selectivity (b) of the DAR.
Figure 3: Effect of pore size in the conversion (a) and selectivity (b) of the DAR.
Figure 4: Comparison of conversion (a) and selectivity (b) of the DAR catalysed by Al-Beta zeolite and MCM-41....
Figure 5: Comparison of conversion (a) and selectivity (b) of the DAR catalysed extra-large pore 3D zeolites.
Figure 6: Effect of the Si/Al ratio in the conversion (a) and selectivity (b) of the DAR.
Figure 7: Effect of the reutilization of the catalysts in the conversion (a) and selectivity (b) of the DAR.
Opportunities and challenges for direct C–H functionalization of piperazines
- Zhishi Ye,
- Kristen E. Gettys and
- Mingji Dai
Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70
- of the lithiated N-Boc-N’-alkylpiperazines with sec-BuLi and TMEDA at −78 °C, the reaction was warmed up to −30 °C with addition of a chiral ligand. The chiral ligand coordinates with the racemic lithiation product to give a diastereomeric mixture which can be resolved under thermodynamic or kinetic
- control with electrophilic quench by a variety of electrophiles. After evaluating a few chiral diamino-alkoxide ligands, ligand 24 was identified as a superior choice. As shown in Figure 7, the result was not optimal with only 30–75% of the desired α-substituted products being obtained and the
Graphical Abstract
Figure 1: Selected piperazine-containing small-molecule pharmaceuticals.
Figure 2: Strategies for the synthesis of carbon-substituted piperazines.
Figure 3: The first α-lithiation of N-Boc-protected piperazines by van Maarseveen et al. in 2005 [37].
Figure 4: α-Lithiation of N-Boc-N’-tert-butyl piperazines by Coldham et al. in 2010 [38].
Figure 5: Diamine-free α-lithiation of N-Boc-piperazines by O’Brien, Campos, et al. in 2010 [40].
Figure 6: The first enantioselective α-lithiation of N-Boc-piperazines by McDermott et al. in 2008 [41].
Figure 7: Dynamic thermodynamic resolution of lithiated of N-Boc-piperazines by Coldham et al. in 2010 [38].
Figure 8: Enantioselective α-lithiation of N-Boc-N’-alkylpiperazines by O’Brien et al. in 2013 and 2016 [42,43].
Figure 9: Asymmetric α-functionalization of N-Boc-piperazines with Ph2CO by O’Brien et al. in 2016 [43].
Figure 10: A “chiral auxiliary” strategy toward enantiopure α-functionalized piperazines by O’Brien et al. 201...
Figure 11: Installation of methyl group at the α-position of piperazines by O’Brien et al. 2016 [43].
Figure 12: α-Lithiation trapping of C-substituted N-Boc-piperazines by O’Brien et al. 2016 [43].
Figure 13: Rh-catalyzed reactions of N-(2-pyridinyl)piperazines by Murai et al. in 1997 [52].
Figure 14: Ta-catalyzed hydroaminoalkylation of piperazines by Schafer et al. in 2013 [55].
Figure 15: Photoredox catalysis for α-C–H functionalization of piperazines by MacMillan et al. in 2011 and 201...
Figure 16: Copper-catalyzed aerobic C–H oxidation of piperazines by Touré, Sames, et al. in 2013 [67].
Figure 17: Free radical approach by Undheim et al. in 1994 [68].
Figure 18: Anodic oxidation approach by Nyberg et al. in 1976 [70].
