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Search for "Michael reaction" in Full Text gives 81 result(s) in Beilstein Journal of Organic Chemistry.
Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions
- Rajeev S. Menon,
- Akkattu T. Biju and
- Vijay Nair
Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47
- intermolecular aza-benzoin reaction is followed by an intramolecular oxa-Michael reaction to form the observed product (Scheme 28). Enders reported a cascade reaction which is initiated by an NHC-catalysed aza-benzoin condensation between various aldehydes and nitrosobenzenes to generate the hydroxamic acids 47
Graphical Abstract
Scheme 1: Breslow’s proposal on the mechanism of the benzoin condensation.
Scheme 2: Imidazolium carbene-catalysed homo-benzoin condensation.
Scheme 3: Homo-benzoin condensation in aqueous medium.
Scheme 4: Homobenzoin condensation catalysed by bis(benzimidazolium) salt 8.
Scheme 5: List of assorted chiral NHC-catalysts used for asymmetric homobenzoin condensation.
Scheme 6: A rigid bicyclic triazole precatalyst 15 in an efficient enantioselective benzoin reaction.
Scheme 7: Inoue’s report of cross-benzoin reactions.
Scheme 8: Cross-benzoin reactions catalysed by thiazolium salt 17.
Scheme 9: Catalyst-controlled divergence in cross-benzoin reactions.
Scheme 10: Chemoselective cross-benzoin reactions catalysed by a bulky NHC.
Scheme 11: Selective intermolecular cross-benzoin condensation reactions of aromatic and aliphatic aldehydes.
Scheme 12: Chemoselective cross-benzoin reaction of aliphatic and aromatic aldehydes.
Scheme 13: Cross-benzoin reactions of trifluoromethyl ketones developed by Enders.
Scheme 14: Cross-benzoin reactions of aldehydes and α-ketoesters.
Scheme 15: Enantioselective cross-benzoin reactions of aliphatic aldehydes and α-ketoesters.
Scheme 16: Dynamic kinetic resolution of β-halo-α-ketoesters via cross-benzoin reaction.
Scheme 17: Enantioselective benzoin reaction of aldehydes and alkynones.
Scheme 18: Aza-benzoin reaction of aldehydes and acylimines.
Scheme 19: NHC-catalysed diastereoselective synthesis of cis-2-amino 3-hydroxyindanones.
Scheme 20: Cross-aza-benzoin reactions of aldehydes with aromatic imines.
Scheme 21: Enantioselective cross aza-benzoin reaction of aliphatic aldehydes with N-Boc-imines.
Scheme 22: Chemoselective cross aza-benzoin reaction of aldehydes with N-PMP-imino esters.
Scheme 23: NHC-catalysed coupling reaction of acylsilanes with imines.
Scheme 24: Thiazolium salt-mediated enantioselective cross-aza-benzoin reaction.
Scheme 25: Aza-benzoin reaction of enals with activated ketimines.
Scheme 26: Isatin derived ketimines as electrophiles in cross aza-benzoin reaction with enals.
Scheme 27: Aza-benzoin reaction of aldehydes and phosphinoylimines catalysed by the BAC-carbene.
Scheme 28: Nitrosoarenes as the electrophilic component in benzoin-initiated cascade reaction.
Scheme 29: One-pot synthesis of hydroxamic esters via aza-benzoin reaction.
Scheme 30: Cookson and Lane’s report of intramolecular benzoin condensation.
Scheme 31: Intramolecular cross-benzoin condensation between aldehyde and ketone moieties.
Scheme 32: Intramolecular crossed aldehyde-ketone benzoin reactions.
Scheme 33: Enantioselective intramolecular crossed aldehyde-ketone benzoin reaction.
Scheme 34: Chromanone synthesis via enantioselective intramolecular cross-benzoin reaction.
Scheme 35: Intramolecular cross-benzoin reaction of chalcones.
Scheme 36: Synthesis of bicyclic tertiary alcohols by intramolecular benzoin reaction.
Scheme 37: A multicatalytic Michael–benzoin cascade process for cyclopentanone synthesis.
Scheme 38: Enamine-NHC dual-catalytic, Michael–benzoin cascade reaction.
Scheme 39: Iminium-cross-benzoin cascade reaction of enals and β-oxo sulfones.
Scheme 40: Intramolecular benzoin condensation of carbohydrate-derived dialdehydes.
Scheme 41: Enantioselective intramolecular benzoin reactions of N-tethered keto-aldehydes.
Scheme 42: Asymmetric cross-benzoin reactions promoted by camphor-derived catalysts.
Scheme 43: NHC-Brønsted base co-catalysis in a benzoin–Michael–Michael cascade.
Scheme 44: Divergent catalytic dimerization of 2-formylcinnamates.
Scheme 45: One-pot, multicatalytic asymmetric synthesis of tetrahydrocarbazole derivatives.
Scheme 46: NHC-chiral secondary amine co-catalysis for the synthesis of complex spirocyclic scaffolds.
Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors
- Ming-Liang Zhang,
- Deng-Feng Yue,
- Zhen-Hua Wang,
- Yuan Luo,
- Xiao-Ying Xu,
- Xiao-Mei Zhang and
- Wei-Cheng Yuan
Beilstein J. Org. Chem. 2016, 12, 295–300, doi:10.3762/bjoc.12.31
- bifunctional multiple hydrogen-bond amine-thiourea-catalyzed Michael reaction of acetyl phosphonates with nitroolefins, giving a series of β-substituted nitro compounds with excellent stereoselectivity [34]. Therefore, as part of our research program aimed at establishing new methods for the construction of
Graphical Abstract
Scheme 1: The strategy to construct chiral 3-substituted-3-hydroxy-1H-pyrrol-2(3H)-ones.
Figure 1: The X-ray structure of compound 4i.
Figure 2: A proposed transition state for the asymmetric Henry reaction.
Catalytic asymmetric formal synthesis of beraprost
- Yusuke Kobayashi,
- Ryuta Kuramoto and
- Yoshiji Takemoto
Beilstein J. Org. Chem. 2015, 11, 2654–2660, doi:10.3762/bjoc.11.285
- enantioselective intramolecular oxa-Michael reaction of an α,β-unsaturated amide mediated by a newly developed benzothiadiazine catalyst. The Weinreb amide moiety and bromo substituent of the Michael adduct were utilized for the C–C bond formations to construct the scaffold. All four contiguous stereocenters of
- few asymmetric syntheses relying on the optical resolution of racemic intermediates [16][17][18][23]. Herein we report the first catalytic asymmetric synthesis of the key intermediate 2 through organocatalyzed-enantioselective intramolecular oxa-Michael reaction [24][25][26]. Results and Discussion
- condensation followed by diazo-transfer reaction. The chiral dihydrobenzofuran scaffold (5 or 6) could be synthesized by asymmetric intramolecular oxa-Michael reaction (AIOM) of α,β-unsaturated amides 7 or 8. Such reactions are generally considered to be challenging due to low nucleophilicity of the oxygen
Graphical Abstract
Figure 1: Structure of PGI2 and beraprost (1).
Scheme 1: Retrosynthetic analysis of beraprost (1).
Scheme 2: Preparation of Michael precursors 7 and 8.
Scheme 3: First attempt at the synthesis of 2 from 6.
Scheme 4: Achievement of a formal synthesis of 2.
Organocatalytic and enantioselective Michael reaction between α-nitroesters and nitroalkenes. Syn/anti-selectivity control using catalysts with the same absolute backbone chirality
- Jose I. Martínez,
- Uxue Uria,
- Maria Muñiz,
- Efraím Reyes,
- Luisa Carrillo and
- Jose L. Vicario
Beilstein J. Org. Chem. 2015, 11, 2577–2583, doi:10.3762/bjoc.11.277
- Jose I. Martinez Uxue Uria Maria Muniz Efraim Reyes Luisa Carrillo Jose L. Vicario Department of Organic Chemistry II, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain 10.3762/bjoc.11.277 Abstract The asymmetric and catalytic Michael reaction between α-nitroesters and
- extension of this behaviour to the Michael reaction between α-substituted nitroacetates and nitroalkenes. The Michael reaction is regarded as a fundamental tool for the formation of C–C bonds during the synthesis of complex molecules [33][34][35], in particular, being able to control both the simple and the
- , isolating the other possible diastereoisomer anti-3a in good yield, 88:12 dr and 90% ee. Once we had confirmed the good performance of the reaction in this intermolecular Michael reaction, we proceeded to evaluate the scope of this transformation in order to establish whether this method could be useful and
Graphical Abstract
Scheme 1: Diastereodivergent cascade Michael/Michael reaction using catalysts with the same absolute chiralit...
Scheme 2: Diastereodivergent enantioselective Michael reaction using ethyl 2-nitropropanoate and β-nitrostyre...
Figure 1: ORTEP diagrams for anti-3a and syn-3o respectively.
Scheme 3: Proposed models to explain the stereochemical outcome of the reaction.
Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams
- Katherine M. Byrd
Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60
- development of asymmetric variants of the Michael reaction. In early studies, chemists relied on chiral auxiliaries [5], heterocuprates [15][16], or natural product-based [17] ligands to induce high to modest stereoselectivity. In 1991, Alexandre Alexakis and co-workers reported the first asymmetric conjugate
- initial discovery [176][177], the Mukaiyama–Michael reaction has emerged as a reliable alternative to the use of metal enolates as nucleophiles in Michael reactions. Katsuki and co-workers reported the first application of this reaction to α,β-unsaturated amides [178]. Their reactions were promoted by
Graphical Abstract
Scheme 1: Generic mechanism for the conjugate addition reaction.
Figure 1: Methods to activate unsaturated amide/lactam systems.
Scheme 2: DCA of Grignard reagents to an L-ephedrine derived chiral α,β–unsaturated amide.
Figure 2: Chiral auxiliaries used in DCA reactions.
Scheme 3: Comparison between auxiliary 5 and the Oppolzer auxiliary in a DCA reaction.
Scheme 4: Use of Evans auxiliary in a DCA reaction.
Figure 3: Lewis acid complex of the Evans auxiliary [43].
Scheme 5: DCA reactions of α,β-unsaturated amides utilizing (S,S)-(+)-pseudoephedrine and the OTBS-derivative...
Figure 4: Proposed model accounting for the diastereoselectivity observed in the 1,4-addition of Bn2NLi to α,...
Scheme 6: An example of a tandem conjugate addition–α-alkylation reaction of an α,β-unsaturated amide utilizi...
Scheme 7: Conjugate addition to an α,β-unsaturated bicyclic lactam leading to (+)-paroxetine and (+)-femoxeti...
Scheme 8: Intramolecular conjugate addition reaction to α,β-unsaturated amide.
Scheme 9: Conjugate addition to an α,β-unsaturated pyroglutamate derivative.
Scheme 10: Cu(I)–NHC-catalyzed asymmetric silylation of α,β-unsaturated lactams and amides.
Scheme 11: Asymmetric copper-catalyzed 1,4-borylation of an α,β-unsaturated amide.
Scheme 12: Asymmetric cross-coupling 49 to phenyl chloride.
Scheme 13: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated lactam.
Scheme 14: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide.
Scheme 15: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide using a chiral bicyclic dien...
Scheme 16: Synthesis of (R)-(−)-baclofen through a rhodium-catalyzed asymmetric 1,4-arylation of lactam 58.
Scheme 17: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide and lactam employing organo[...
Scheme 18: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated lactam employing benzofuran-2-ylzi...
Figure 5: Further chiral ligands that have been used in rhodium-catalyzed 1,4-additions of α,β-unsaturated am...
Scheme 19: Palladium-catalyzed asymmetric 1,4-arylation of arylsiloxanes to a α,β-unsaturated lactam.
Scheme 20: SmI2-mediated cyclization of α,β-unsaturated Weinreb amides.
Figure 6: Chiral Lewis acid complexes used in the Mukaiyama–Michael addition of α,β-unsaturated amides.
Scheme 21: Mukaiyama–Michael addition of thioester silylketene acetal to α,β-unsaturated N-alkenoyloxazolidino...
Scheme 22: Asymmetric 1,4-addition of aryl acetylides to α,β-unsaturated thioamides.
Scheme 23: Asymmetric 1,4-addition of alkyl acetylides to α,β-unsaturated thioamides.
Scheme 24: Asymmetric vinylogous conjugate additions of unsaturated butyrolactones to α,β-unsaturated thioamid...
Scheme 25: Gd-catalyzed asymmetric 1,4-cyanation of α,β-unsaturated N-acylpyrroles [205].
Scheme 26: Lewis acid-catalyzed asymmetric 1,4-cyanation of α,β-unsaturated N-acylpyrazole 107.
Scheme 27: Lewis acid mediated 1,4-addition of dibenzyl malonate to α,β-unsaturated N-acylpyrroles.
Scheme 28: Chiral Lewis acid mediated 1,4-radical addition to α,β-unsaturated N-acyloxazolidinone [224].
Scheme 29: Aza-Michael addition of O-benzylhydroxylamine to an α,β-unsaturated N-acylpyrazole.
Scheme 30: An example of the aza-Michael addition of secondary aryl amines to an α,β-unsaturated N-acyloxazoli...
Scheme 31: Aza-Michael additions of anilines to a α,β-unsaturated N-alkenoyloxazolidinone catalyzed by palladi...
Scheme 32: Aza-Michael additions of aniline to an α,β-unsaturated N-alkenoylbenzamide and N-alkenoylcarbamate ...
Scheme 33: Difference between aza-Michael addition ran using the standard protocol versus the slow addition pr...
Scheme 34: Aza-Michael additions of aryl amines salts to an α,β-unsaturated N-alkenoyloxazolidinone catalyzed ...
Scheme 35: Aza-Michael addition of N-alkenoyloxazolidiniones catalyzed by samarium diiodide [244].
Scheme 36: Asymmetric aza-Michael addition of p-anisidine to α,β-unsaturated N-alkenoyloxazolidinones catalyze...
Scheme 37: Asymmetric aza-Michael addition of O-benzylhydroxylamine to N-alkenoyloxazolidinones catalyzed by i...
Scheme 38: Asymmetric 1,4-addition of purine to an α,β-unsaturated N-alkenoylbenzamide catalyzed by (S,S)-(sal...
Scheme 39: Asymmetric 1,4-addition of phosphites to α,β-unsaturated N-acylpyrroles.
Scheme 40: Asymmetric 1,4-addition of phosphine oxides to α,β-unsaturated N-acylpyrroles.
Scheme 41: Tandem Michael-aldol reaction catalyzed by a hydrogen-bonding organocatalyst.
Scheme 42: Examples of the sulfa-Michael–aldol reaction employing α,β-unsaturated N-acylpyrazoles.
Scheme 43: Example of the sulfa-Michael addition of α,β-unsaturated N-alkenoyloxazolidinones.
Figure 7: Structure of cinchona alkaloid-based squaramide catalyst.
Scheme 44: Asymmetric intramolecular oxa-Michael addition of an α,β-unsaturated amide.
Scheme 45: Formal synthesis atorvastatin.
Recent advances in the electrochemical construction of heterocycles
- Robert Francke
Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303
- anodically generated 1,2-benzoquinone undergoes a Michael reaction with 62 under formation of adduct 63, which is further oxidized to give benzoquinone 64. Finally, anellation proceeds in a second Michael addition step under formation of heterocyclic compound 65. In the reported cases, both the generation of
Graphical Abstract
Figure 1: Common types of electrochemically induced cyclization reactions.
Scheme 1: Principle of indirect electrolysis.
Scheme 2: Anodic intramolecular cyclization of olefines in methanol.
Scheme 3: Anodic cyclization of olefines in CH2Cl2/DMSO.
Scheme 4: Intramolecular coupling of 1,6-dienes in CH2Cl2/DMSO.
Scheme 5: Cyclization of bromopropargyloxy ester 12.
Scheme 6: Proposed mechanism for the radical cyclization of bromopropargyloxy ester 12.
Scheme 7: Preparation of pyrrolidines and tetrahydrofurans via Kolbe-type electrolysis of unsaturated carboxy...
Scheme 8: Anodic cyclization of chalcone oximes 19.
Scheme 9: Generation of N-acyliminium (23) and alkoxycarbenium species (24) from amides and ethers with and w...
Scheme 10: Anodic cyclization of dipeptide 25.
Scheme 11: Anodic cyclization of a dipeptide using an electroauxiliary.
Scheme 12: Anodic cyclization of hydroxyamino compound 29.
Scheme 13: Cyclization of unsaturated thioacetals using the ArS(ArSSAr)+ mediator.
Scheme 14: Cyclization of biaryl 35 to carbazol 36 as key-step of the synthesis of glycozoline (37).
Scheme 15: Electrosynthesis of 39 as part of the total synthesis of alkaloids 40 and 41.
Scheme 16: Wacker-type cyclization of alkenyl phenols 42.
Scheme 17: Cathodic synthesis of indol derivatives.
Scheme 18: Fluoride mediated anodic cyclization of α-(phenylthio)acetamides.
Scheme 19: Synthesis of 2-substituted benzoxazoles from Schiff bases.
Scheme 20: Synthesis of euglobal model compounds via electrochemically induced Diels–Alder cycloaddition.
Scheme 21: Cycloaddition of anodically generated N-acyliminium species 58 with olefins and alkynes.
Scheme 22: Electrochemical aziridination of olefins.
Scheme 23: Proposed mechanism for the aziridination reaction.
Scheme 24: Electrochemical synthesis of benzofuran and indole derivatives.
Scheme 25: Anodic anellation of catechol derivatives 66 with different 1,3-dicarbonyl compounds.
Scheme 26: Electrosynthesis of 1,2-fused indoles from catechol and ketene N,O-acetals.
Scheme 27: Reaction of N-acyliminium pools with olefins having a nucleophilic substituent.
Scheme 28: Synthesis of thiochromans using the cation-pool method.
Scheme 29: Electrochemical synthesis and diversity-oriented modification of 73.
Chiral phosphines in nucleophilic organocatalysis
- Yumei Xiao,
- Zhanhu Sun,
- Hongchao Guo and
- Ohyun Kwon
Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218
- enantioselectivity. In a relatively successful example, the chiral aminophosphine G9 catalyzed the asymmetric double-Michael reaction between o-tosylamidophenyl malonate and 3-butyn-2-one to give the indoline derivative in 69% yield and up to 10% ee (Scheme 53). 2.15 Annulation through tandem Michael addition/Wittig
Graphical Abstract
Figure 1: Cyclic chiral phosphines based on bridged-ring skeletons.
Figure 2: Cyclic chiral phosphines based on binaphthyl skeletons.
Figure 3: Cyclic chiral phosphines based on ferrocene skeletons.
Figure 4: Cyclic chiral phosphines based on spirocyclic skeletons.
Figure 5: Cyclic chiral phosphines based on phospholane ring skeletons.
Figure 6: Acyclic chiral phosphines.
Figure 7: Multifunctional chiral phosphines based on binaphthyl skeletons.
Figure 8: Multifunctional chiral phosphines based on amino acid skeletons.
Scheme 1: Asymmetric [3 + 2] annulations of allenoates with electron-deficient olefins, catalyzed by the chir...
Scheme 2: Asymmetric [3 + 2] annulations of allenoate and enones, catalyzed by the chiral binaphthyl-based ph...
Scheme 3: Asymmetric [3 + 2] annulations of N-substituted olefins and allenoates, catalyzed by the chiral bin...
Scheme 4: Asymmetric [3 + 2] annulations of 2-aryl-1,1-dicyanoethylenes with ethyl allenoate, catalyzed by th...
Scheme 5: Asymmetric [3 + 2] annulations of 3-alkylideneindolin-2-ones with ethyl allenoate, catalyzed by the...
Scheme 6: Asymmetric [3 + 2] annulations of 2,6-diarylidenecyclohexanones with allenoates, catalyzed by the c...
Scheme 7: Asymmetric [3 + 2] annulations of allenoate with alkylidene azlactones, catalyzed by the chiral bin...
Scheme 8: Asymmetric [3 + 2] annulations of C60 with allenoates, catalyzed by the chiral phosphine B6.
Scheme 9: Asymmetric [3 + 2] annulations of α,β-unsaturated esters and ketones with an allenoate, catalyzed b...
Scheme 10: Asymmetric [3 + 2] annulations of exocyclic enones with allenoates, catalyzed by the ferrocene-modi...
Scheme 11: Asymmetric [3 + 2] annulations of enones with an allenylphosphonate, catalyzed by the ferrocene-mod...
Scheme 12: Asymmetric [3 + 2] annulations of 3-alkylidene-oxindoles with ethyl allenoate, catalyzed by the fer...
Scheme 13: Asymmetric [3 + 2] annulations of dibenzylideneacetones with ethyl allenoate, catalyzed by the ferr...
Scheme 14: Asymmetric [3 + 2] annulations of trisubstituted alkenes with ethyl allenoate, catalyzed by the fer...
Scheme 15: Asymmetric [3 + 2] annulations of 2,6-diarylidenecyclohexanones with allenoates, catalyzed by the f...
Scheme 16: Asymmetric [3 + 2] annulations of α,β-unsaturated ketones with ethyl allenoates, catalyzed by the f...
Scheme 17: Asymmetric [3 + 2] annulations of α,β-unsaturated esters with allenoates, catalyzed by the ferrocen...
Scheme 18: Asymmetric [3 + 2] annulations of alkylidene azlactones with allenoates, catalyzed by the chiral sp...
Scheme 19: Asymmetric [3 + 2] annulations of α-trimethylsilyl allenones and electron-deficient olefins, cataly...
Scheme 20: Asymmetric [3 + 2] annulations of α,β-unsaturated ketones with an allenone, catalyzed by the chiral...
Scheme 21: Asymmetric [3 + 2] annulations of cyclic enones with allenoates, catalyzed by the chiral α-amino ac...
Scheme 22: Asymmetric [3 + 2] annulations of arylidenemalononitriles and analogues with an allenoate, catalyze...
Scheme 23: Asymmetric [3 + 2] annulations of α,β-unsaturated esters with an allenoate, catalyzed by the chiral...
Scheme 24: Asymmetric [3 + 2] annulations of 3,5-dimethyl-1H-pyrazole-derived acrylamides with an allenoate, c...
Scheme 25: Asymmetric [3 + 2] annulations of maleimides with allenoates, catalyzed by the chiral phosphine H10....
Scheme 26: Asymmetric [3 + 2] annulations of α-substituted acrylates with allenoate, catalyzed by the chiral p...
Scheme 27: Asymmetric [3 + 2] annulation of an N-tosylimine with an allenoate, catalyzed by the chiral phosphi...
Scheme 28: Asymmetric [3 + 2] annulations of N-tosylimines with an allenoate, catalyzed by the chiral phosphin...
Scheme 29: Asymmetric [3 + 2] annulations of N-tosylimines with an allenoate, catalyzed by the chiral phosphin...
Scheme 30: Asymmetric [3 + 2] annulations of N-diphenylphosphinoyl aromatic imines with butynoates, catalyzed ...
Scheme 31: Asymmetric [3 + 2] annulations of N-tosylimines with allenylphosphonates, catalyzed by the chiral p...
Scheme 32: Asymmetric [3 + 2] annulation of an N-tosylimine with an allenoate, catalyzed by the chiral phosphi...
Scheme 33: Asymmetric [3 + 2] annulations of N-diphenylphosphinoyl aromatic imines with allenoates (top), cata...
Scheme 34: Asymmetric [3 + 2] annulation of N-diphenylphosphinoylimines with allenoates, catalyzed by the chir...
Scheme 35: Asymmetric [3 + 2] annulation of an azomethine imine with an allenoate, catalyzed by the chiral pho...
Scheme 36: Asymmetric [3 + 2] annulations between α,β-unsaturated esters/ketones and 3-butynoates, catalyzed b...
Scheme 37: Asymmetric intramolecular [3 + 2] annulations of electron-deficient alkenes and MBH carbonates, cat...
Scheme 38: Asymmetric [3 + 2] annulations of methyleneindolinone and methylenebenzofuranone derivatives with M...
Scheme 39: Asymmetric [3 + 2] annulations of activated isatin-based alkenes with MBH carbonates, catalyzed by ...
Scheme 40: Asymmetric [3 + 2] annulations of maleimides with MBH carbonates, catalyzed by the chiral phosphine ...
Scheme 41: A series of [3 + 2] annulations of various activated alkenes with MBH carbonates, catalyzed by the ...
Scheme 42: Asymmetric [3 + 2] annulations of an alkyne with isatins, catalyzed by the chiral phosphine F1.
Scheme 43: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphine B1.
Scheme 44: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphine H5.
Scheme 45: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphines H13 and H12.
Scheme 46: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphine H6.
Scheme 47: Kerrigan’s [2 + 2] annulations of ketenes with imines, catalyzed by the chiral phosphine B7.
Scheme 48: Asymmetric [4 + 1] annulations, catalyzed by the chiral phosphine G6.
Scheme 49: Asymmetric homodimerization of ketenes, catalyzed by the chiral phosphine F5 and F6.
Scheme 50: Aza-MBH/Michael reactions, catalyzed by the chiral phosphine G1.
Scheme 51: Tandem RC/Michael additions, catalyzed by the chiral phosphine H14.
Scheme 52: Intramolecular tandem RC/Michael addition, catalyzed by the chiral phosphine H15.
Scheme 53: Double-Michael addition, catalyzed by the chiral aminophosphine G9.
Scheme 54: Tandem Michael addition/Wittig olefinations, mediated by the chiral phosphine BIPHEP.
Scheme 55: Asymmetric Michael additions, catalyzed by the chiral phosphines H7, H8, and H9.
Scheme 56: Asymmetric γ-umpolung additions, catalyzed by the chiral phosphine A1.
Scheme 57: Asymmetric γ-umpolung additions, catalyzed by the chiral phosphines E2 and E3.
Scheme 58: Intramolecular γ-additions of hydroxy-2-alkynoates, catalyzed by the chiral phosphine D2.
Scheme 59: Intra-/intermolecular γ-additions, catalyzed by the chiral phosphine D2.
Scheme 60: Intermolecular γ-additions, catalyzed by the chiral phosphines B5 and B3.
Scheme 61: Intermolecular γ-additions, catalyzed by the chiral phosphines E6 and B4.
Scheme 62: Asymmetric allylic substitution of MBH acetates, catalyzed by the chiral phosphine G2.
Scheme 63: Allylic substitutions between MBH acetates or carbonates and an array of nucleophiles, catalyzed by...
Scheme 64: Asymmetric acylation of diols, catalyzed by the chiral phosphines E4 and E5.
Scheme 65: Kinetic resolution of secondary alcohols, catalyzed by the chiral phosphine E8 and E9.
Primary-tertiary diamine-catalyzed Michael addition of ketones to isatylidenemalononitrile derivatives
- Akshay Kumar and
- Swapandeep Singh Chimni
Beilstein J. Org. Chem. 2014, 10, 929–935, doi:10.3762/bjoc.10.91
- -component version of the reaction by a domino Knoevenagel–Michael sequence. The Michael adduct 4a was transformed into spirooxindole 6 by a reduction with sodium borohydride in a highly enantioselective manner. Keywords: 3,3'-disubstituted oxindoles; Michael reaction; organocatalysis; primary-tertiary
- diamine; spirooxindoles; Introduction The Michael reaction is one of the fundamental carbon–carbon bond forming reactions in organic synthesis, since a plethora of carbon nucleophiles and activated olefins could be expected to give versatile arrangements [1][2][3][4][5][6][7][8]. Among the various
- -tertiary diamine organocatalysts for Michael reaction via enamine activation has not been investigated so far [38]. With readily available and inexpensive natural amino acids as a chiral source, we developed very simple primary-tertiary diamine organocatalysts (Figure 2) for asymmetric aldol reactions [44
Graphical Abstract
Figure 1: Oxindole based Michael acceptors.
Figure 2: Primary-tertiary diamine organocatalysts.
Scheme 1: Diamine catalyzed Michael addition of acetone to isatylidenemalononitrile.
Scheme 2: Substrate scope of the addition of 2 with 3 catalyzed by 1a D-CSA.
Scheme 3: One-pot, three-component Knoevenagel condensation–Michael addition.
Scheme 4: Cascade reduction–cyclization for the synthesis of spirooxindole.
Phosphinate-containing heterocycles: A mini-review
- Olivier Berger and
- Jean-Luc Montchamp
Beilstein J. Org. Chem. 2014, 10, 732–740, doi:10.3762/bjoc.10.67
- synthesis of chiral bicyclic phosphinates 23a–k by domino hydrophosphinylation/Michael/Michael reaction was realized by Fourgeaud et al. (Scheme 10) [25]. Several 1-oxa-3-aza-6-phosphabicyclo[3.3.0]octanes derivatives 23a–k were obtained in yields around 70% by reacting allenes 21 with imines 22 derived
- malonate anion. Tandem hydrophosphinylation/Michael/Michael reaction of allenyl-H-phosphinates. 5-Membered “cyclo-PALA” via intramolecular Mitsunobu reaction. 6-Membered “cyclo-PALA” via intramolecular Mitsunobu reaction. Intramolecular Kabachnik–Fields reaction. Tandem Kabachnik–Fields/alkylation reaction
Graphical Abstract
Scheme 1: McCormack synthesis.
Scheme 2: Ring-closing metathesis.
Scheme 3: Phospha-Dieckmann condensation.
Scheme 4: Palladium-catalyzed oxidative arylation.
Scheme 5: Tandem cross-coupling/Dieckmann condensation.
Scheme 6: Rhodium-catalyzed double [2 + 2 + 2] cycloaddition.
Scheme 7: Silver oxide-mediated alkyne–arene annulation.
Scheme 8: Silver acetate-mediated alkyne–arene annulation.
Scheme 9: Cyclization through phosphinylation/alkylation of malonate anion.
Scheme 10: Tandem hydrophosphinylation/Michael/Michael reaction of allenyl-H-phosphinates.
Scheme 11: 5-Membered “cyclo-PALA” via intramolecular Mitsunobu reaction.
Scheme 12: 6-Membered “cyclo-PALA” via intramolecular Mitsunobu reaction.
Scheme 13: Intramolecular Kabachnik–Fields reaction.
Scheme 14: Tandem Kabachnik–Fields/alkylation reaction.
Scheme 15: Tandem Kabacknik–Fields/C–N cross-coupling reaction.
Scheme 16: Tandem Kabacknik–Fields/C-P cross-coupling reaction.
Scheme 17: Heterocyclization via amide formation.
Scheme 18: Cyclization via reductive amination.
Scheme 19: H-Phosphinate alkylation.
Scheme 20: Cyclization through intramolecular Michael addition.
Scheme 21: Double Arbuzov reaction of bis(trimethylsiloxy)phosphine.
Scheme 22: Diastereoselective ring-closing metathesis.
Scheme 23: 2-Ketophosphonate/benzene annulation.
Scheme 24: Tandem Kabachnik–Fields/transesterification reaction.
Scheme 25: Tandem Kabachnik–Fields/transesterification reaction with oxazolidine.
Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics
- Gijs Koopmanschap,
- Eelco Ruijter and
- Romano V.A. Orru
Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50
- tautomerizes, the authors proposed a plausible mechanism, in which tautomer 113 undergoes cyclization via an intramolecular Michael reaction to give intermediate 114. The next step involves cleavage of the dimethylamine group to afford the thiazole structures 115. In 2003, the same group also described a solid
Graphical Abstract
Scheme 1: The proposed mechanism of the Passerini reaction.
Scheme 2: The PADAM-strategy to α-hydroxy-β-amino amide derivatives 7. An additional oxidation provides α-ket...
Scheme 3: The general accepted Ugi-mechanism.
Scheme 4: Three commonly applied Ugi/cyclization approaches. a) UDC-process, b) UAC-sequence, c) UDAC-combina...
Scheme 5: Ugi reaction that involves the condensation of Armstrong’s convertible isocyanide.
Scheme 6: Mechanism of the U-4C-3CR towards bicyclic β-lactams.
Scheme 7: The Ugi 4C-3CR towards oxabicyclo β-lactams.
Scheme 8: Ugi MCR between an enantiopure monoterpene based β-amino acid, aldehyde and isocyanide resulting in...
Scheme 9: General MCR for β-lactams in water.
Scheme 10: a) Ugi reaction for β-lactam-linked peptidomimetics. b) Varying the β-amino acid resulted in β-lact...
Scheme 11: Ugi-4CR followed by a Pd-catalyzed Sn2 cyclization.
Scheme 12: Ugi-3CR of dipeptide mimics from 2-substituted pyrrolines.
Scheme 13: Joullié–Ugi reaction towards 2,5-disubstituted pyrrolidines.
Scheme 14: Further elaboration of the Ugi-scaffold towards bicyclic systems.
Scheme 15: Dihydroxyproline derivatives from an Ugi reaction.
Scheme 16: Diastereoselective Ugi reaction described by Banfi and co-workers.
Scheme 17: Similar Ugi reaction as in Scheme 16 but with different acids and two chiral isocyanides.
Scheme 18: Highly diastereoselective synthesis of pyrrolidine-dipeptoids via a MAO-N/MCR-procedure.
Scheme 19: MAO-N/MCR-approach towards the hepatitis C drug telaprevir.
Scheme 20: Enantioselective MAO-U-3CR procedure starting from chiral pyrroline 64.
Scheme 21: Synthesis of γ-lactams via an UDC-sequence.
Scheme 22: Utilizing bifunctional groups to provide bicyclic γ-lactam-ketopiperazines.
Scheme 23: The Ugi reaction provided both γ- as δ-lactams depending on which inputs were used.
Scheme 24: The sequential Ugi/RCM with olefinic substrates provided bicyclic lactams.
Scheme 25: a) The structural and dipole similarities of the triazole unit with the amide bond. b) The copper-c...
Scheme 26: The Ugi/Click sequence provided triazole based peptidomimetics.
Scheme 27: The Ugi/Click reaction as described by Nanajdenko.
Scheme 28: The Ugi/Click-approach by Pramitha and Bahulayan.
Scheme 29: The Ugi/Click-combination by Niu et al.
Scheme 30: Triazole linked peptidomimetics obtained from two separate MCRs and a sequential Click reaction.
Scheme 31: Copper-free synthesis of triazoles via two MCRs in one-pot.
Scheme 32: The sequential Ugi/Paal–Knorr reaction to afford pyrazoles.
Scheme 33: An intramolecular Paal–Knorr condensation provided under basic conditions pyrazolones.
Scheme 34: Similar cyclization performed under acidic conditions provided pyrazolones without the trifluoroace...
Scheme 35: The Ugi-4CR towards 2,4-disubstituted thiazoles.
Scheme 36: Solid phase approach towards thiazoles.
Scheme 37: Reaction mechanism of formation of thiazole peptidomimetics containing an additional β-lactam moiet...
Scheme 38: The synthesis of the trisubstituted thiazoles could be either performed via an Ugi reaction with pr...
Scheme 39: Performing the Ugi reaction with DMB-protected isocyanide gave access to either oxazoles or thiazol...
Scheme 40: Ugi/cyclization-approach towards 2,5-disubstituted thiazoles. The Ugi reaction was performed with d...
Scheme 41: Further derivatization of the thiazole scaffold.
Scheme 42: Three-step procedure towards the natural product bacillamide C.
Scheme 43: Ugi-4CR to oxazoles reported by Zhu and co-workers.
Scheme 44: Ugi-based synthesis of oxazole-containing peptidomimetics.
Scheme 45: TMNS3 based Ugi reaction for peptidomimics containing a tetrazole.
Scheme 46: Catalytic cycle of the enantioselective Passerini reaction towards tetrazole-based peptidomimetics.
Scheme 47: Tetrazole-based peptidomimetics via an Ugi reaction and a subsequent sigmatropic rearrangement.
Scheme 48: Resin-bound Ugi-approach towards tetrazole-based peptidomimetics.
Scheme 49: Ugi/cyclization approach towards γ/δ/ε-lactam tetrazoles.
Scheme 50: Ugi-3CR to pipecolic acid-based peptidomimetics.
Scheme 51: Staudinger–Aza-Wittig/Ugi-approach towards pipecolic acid peptidomimetics.
Figure 1: The three structural isomers of diketopiperazines. The 2,5-DKP isomer is most common.
Scheme 52: UDC-approach to obtain 2,5-DKPs, either using Armstrong’s isocyanide or via ethylglyoxalate.
Scheme 53: a) Ugi reaction in water gave either 2,5-DKP structures or spiro compounds. b) The Ugi reaction in ...
Scheme 54: Solid-phase approach towards diketopiperazines.
Scheme 55: UDAC-approach towards DKPs.
Scheme 56: The intermediate amide is activated as leaving group by acid and microwave assisted organic synthes...
Scheme 57: UDC-procedure towards active oxytocin inhibitors.
Scheme 58: An improved stereoselective MCR-approach towards the oxytocin inhibitor.
Scheme 59: The less common Ugi reaction towards DKPs, involving a Sn2-substitution.
Figure 2: Spatial similarities between a natural β-turn conformation and a DKP based β-turn mimetic [158].
Scheme 60: Ugi-based syntheses of bicyclic DKPs. The amine component is derived from a coupling between (R)-N-...
Scheme 61: Ugi-based synthesis of β-turn and γ-turn mimetics.
Figure 3: Isocyanide substituted 3,4-dihydropyridin-2-ones, dihydropyridines and the Freidinger lactams. Bio-...
Scheme 62: The mechanism of the 4-CR towards 3,4-dihydropyridine-2-ones 212.
Scheme 63: a) Multiple MCR-approach to provide DHP-peptidomimetic in two-steps. b) A one-pot 6-CR providing th...
Scheme 64: The MCR–alkylation–MCR procedure to obtain either tetrapeptoids or depsipeptides.
Scheme 65: U-3CR/cyclization employing semicarbazone as imine component gave triazine based peptidomimetics.
Scheme 66: 4CR towards triazinane-diones.
Scheme 67: The MCR–alkylation–IMCR-sequence described by our group towards triazinane dione-based peptidomimet...
Scheme 68: Ugi-4CR approaches followed by a cyclization to thiomorpholin-ones (a) and pyrrolidines (b).
Scheme 69: UDC-approach for benzodiazepinones.
Scheme 70: Ugi/Mitsunobu sequence to BDPs.
Scheme 71: A UDAC-approach to BDPs with convertible isocyanides. The corresponding amide is cleaved by microwa...
Scheme 72: microwave assisted post condensation Ugi reaction.
Scheme 73: Benzodiazepinones synthesized via the post-condensation Ugi/ Staudinger–Aza-Wittig cyclization.
Scheme 74: Two Ugi/cyclization approaches utilizing chiral carboxylic acids. Reaction (a) provided the product...
Scheme 75: The mechanism of the Gewald-3CR includes three base-catalysed steps involving first a Knoevnagel–Co...
Scheme 76: Two structural 1,4-thienodiazepine-2,5-dione isomers by U-4CR/cyclization.
Scheme 77: Tetrazole-based diazepinones by UDC-procedure.
Scheme 78: Tetrazole-based BDPs via a sequential Ugi/hydrolysis/coupling.
Scheme 79: MCR synthesis of three different tricyclic BPDs.
Scheme 80: Two similar approaches both involving an Ugi reaction and a Mitsunobu cyclization.
Scheme 81: Mitsunobu–Ugi-approach towards dihydro-1,4-benzoxazepines.
Scheme 82: Ugi reaction towards hetero-aryl fused 5-oxo-1,4-oxazepines.
Scheme 83: a) Ugi/RCM-approach towards nine-membered peptidomimetics b) Sequential peptide-coupling, deprotect...
Scheme 84: Ugi-based synthesis towards cyclic RGD-pentapeptides.
Scheme 85: Ugi/MCR-approach towards 12–15 membered macrocycles.
Scheme 86: Stereoselective Ugi/RCM approach towards 16-membered macrocycles.
Scheme 87: Passerini/RCM-sequence to 22-membered macrocycles.
Scheme 88: UDAC-approach towards 12–18-membered depsipeptides.
Figure 4: Enopeptin A with its more active derivative ADEP-4.
Scheme 89: a) The Joullié–Ugi-approach towards ADEP-4 derivatives b) Ugi-approach for the α,α-dimethylated der...
Scheme 90: Ugi–Click-strategy for 15-membered macrocyclic glyco-peptidomimetics.
Scheme 91: Ugi/Click combinations provided macrocycles containing both a triazole and an oxazole moiety.
Scheme 92: a) A solution-phase procedure towards macrocycles. b) Alternative solid-phase synthesis as was repo...
Scheme 93: Ugi/cyclization towards cyclophane based macrocycles.
Scheme 94: PADAM-strategy towards eurystatin A.
Scheme 95: PADAM-approach for cyclotheanamide.
Scheme 96: A triple MCR-approach affording RGD-pentapeptoids.
Scheme 97: Ugi-MiBs-approach towards peptoid macrocycles.
Scheme 98: Passerini-based MiB approaches towards macrocycles 345 and 346.
Scheme 99: Macrocyclic peptide formation by the use of amphoteric aziridine-based aldehydes.
Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes
- Ludovic Eberlin,
- Fabien Tripoteau,
- François Carreaux,
- Andrew Whiting and
- Bertrand Carboni
Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19
- based on a first Diels–Alder cycloaddition, as shown above. However, a recent report of Norsikian, Beau and co-workers described a novel sequence of tandem transformations which combined the Petasis reaction, intramolecular [4 + 2]-cycloaddition, cross metathesis and Michael reaction. This process gave
Graphical Abstract
Scheme 1: 1-Boron-substituted 1,3-diene in a tandem cycloaddition [4 + 2]/allylboration sequence.
Scheme 2: Lewis acid catalyst in the tandem cycloaddition [4 + 2]/allylboration sequence.
Scheme 3: Synthesis of an advanced precursor of clerodin.
Scheme 4: Intramolecular Diels–Alder/allylboration sequence.
Scheme 5: Diastereoselective Diels–Alder reaction with N-phenylmaleimide and 4-phenyltriazoline-3,5-dione.
Scheme 6: Asymmetric synthesis of a α-hydroxyalkylcyclohexane.
Scheme 7: Tandem [4 + 2]-cycloaddition/allylboration of 3-silyloxy- and 4-alkoxy-dienyl boronates.
Scheme 8: Metal-mediated cycloisomerization/Diels–Alder reaction/allylboration sequence.
Scheme 9: Cobalt-catalyzed Diels–Alder/allylboration sequence.
Scheme 10: A two-step reaction sequence for the synthesis of tetrahydronaphthalenes 12.
Scheme 11: Tandem sequence based on the Petasis borono–Mannich reaction as first key step.
Scheme 12: One-pot tandem dimerization/allylboration reaction of 1,3-diene-2-boronate.
Scheme 13: Tandem Diels–Alder/cross-coupling reactions of trifluoroborates 15.
Scheme 14: Diels–Alder/cross-coupling reactions of 16.
Scheme 15: Metal catalyzed tandem Diels–Alder/hydrolysis reactions.
Scheme 16: Synthesis of anti-1,5-diols 18 by triple aldehyde addition.
Scheme 17: Catalytic enantioselective three-component hetero-[4 + 2]-cycloaddition/allylboration sequence.
Scheme 18: Synthesis of natural products using the catalytic enantioselective HDA/allylboration sequence.
Scheme 19: Total synthesis of a thiomarinol derivative.
Scheme 20: Synthesis of an advanced intermediate 27 for the east fragment of palmerolide A.
Scheme 21: Bicyclic piperidines from tandem aza-[4 + 2]-cycloaddition/allylboration.
Scheme 22: Hydrogenolysis reactions of hydrazinopiperidines.
Scheme 23: Tandem aza-[4 + 2]-cycloaddition/allylboration/retrosulfinyl-ene sequence.
Scheme 24: Boronated heterodendralene 32 in [4 + 2]-cycloadditions.
Scheme 25: Synthesis of tricyclic imides derivatives.
Scheme 26: Synthesis of 37 via a HDA/allylboration/DA sequence.
Scheme 27: Diels–Alder/allylboration sequence.
Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products
- Alexander O. Terent'ev,
- Dmitry A. Borisov,
- Vera A. Vil’ and
- Valery M. Dembitsky
Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6
- 1,2-dioxolanes represents an intramolecular version of the Michael reaction, in which the hydroperoxide group acts as the nucleophile. Generally, the reaction is performed in fluorinated alcohols (CF3CH2OH or (CF3)2CHOH) in the presence of diethylamine or, in some cases, of cesium hydroxide. Initially
Graphical Abstract
Figure 1: Five and six-membered cyclic peroxides.
Figure 2: Artemisinin and semi-synthetic derivatives.
Scheme 1: Synthesis of 3-hydroxy-1,2-dioxolanes 3a–c.
Scheme 2: Synthesis of dioxolane 6.
Scheme 3: Photooxygenation of oxazolidines 7a–d with formation of spiro-fused oxazolidine-containing dioxolan...
Scheme 4: Oxidation of cyclopropanes 10a–e and 11a–e with preparation of 1,2-dioxolanes 12a–e.
Scheme 5: VO(acac)2-catalyzed oxidation of silylated bicycloalkanols 13a–c.
Scheme 6: Mn(II)-catalyzed oxidation of cyclopropanols 15a–g.
Scheme 7: Oxidation of aminocyclopropanes 20a–c.
Scheme 8: Synthesis of aminodioxolanes 24.
Figure 3: Trifluoromethyl-containing dioxolane 25.
Scheme 9: Synthesis of 1,2-dioxolanes 27a–e by the oxidation of cyclopropanes 26a–e.
Scheme 10: Photoinduced oxidation of methylenecyclopropanes 28.
Scheme 11: Irradiation-mediated oxidation.
Scheme 12: Application of diazene 34 for dioxolane synthesis.
Scheme 13: Mn(OAc)3-catalyzed cooxidation of arylacetylenes 37a–h and acetylacetone with atmospheric oxygen.
Scheme 14: Peroxidation of (2-vinylcyclopropyl)benzene (40).
Scheme 15: Peroxidation of 1,4-dienes 43a,b.
Scheme 16: Peroxidation of 1,5-dienes 46.
Scheme 17: Peroxidation of oxetanes 53a,b.
Scheme 18: Peroxidation of 1,6-diene 56.
Scheme 19: Synthesis of 3-alkoxy-1,2-dioxolanes 62a,b.
Scheme 20: Synthesis of spiro-bis(1,2-dioxolane) 66.
Scheme 21: Synthesis of dispiro-1,2-dioxolanes 68, 70, 71.
Scheme 22: Synthesis of spirohydroperoxydioxolanes 75a,b.
Scheme 23: Synthesis of spirohydroperoxydioxolane 77 and dihydroperoxydioxolane 79.
Scheme 24: Ozonolysis of azepino[4,5-b]indole 80.
Scheme 25: SnCl4-mediated fragmentation of ozonides 84a–l in the presence of allyltrimethylsilane.
Scheme 26: SnCl4-mediated fragmentation of bicyclic ozonide 84m in the presence of allyltrimethylsilane.
Scheme 27: MCl4-mediated fragmentation of alkoxyhydroperoxides 96 in the presence of allyltrimethylsilane.
Scheme 28: SnCl4-catalyzed reaction of monotriethylsilylperoxyacetal 108 with alkene 109.
Scheme 29: SnCl4-catalyzed reaction of triethylsilylperoxyacetals 111 with alkenes.
Scheme 30: Desilylation of tert-butyldimethylsilylperoxy ketones 131a,b followed by cyclization.
Scheme 31: Deprotection of peroxide 133 followed by cyclization.
Scheme 32: Asymmetric peroxidation of methyl vinyl ketones 137a–e.
Scheme 33: Et2NH-catalyzed intramolecular cyclization.
Scheme 34: Synthesis of oxodioxolanes 143a–j.
Scheme 35: Haloperoxidation accompanied by intramolecular ring closure.
Scheme 36: Oxidation of triterpenes 149a–d with Na2Cr2O7/N-hydroxysuccinimide.
Scheme 37: Curtius and Wolff rearrangements to form 1,2-dioxolane ring-retaining products.
Scheme 38: Oxidative desilylation of peroxide 124.
Scheme 39: Synthesis of dioxolane 158, a compound containing the aminoquinoline antimalarial pharmacophore.
Scheme 40: Diastereomers of plakinic acid A, 162a and 162b.
Scheme 41: Ozonolysis of alkenes.
Scheme 42: Cross-ozonolysis of alkenes 166 with carbonyl compounds.
Scheme 43: Ozonolysis of the bicyclic cyclohexenone 168.
Scheme 44: Cross-ozonolysis of enol ethers 172a,b with cyclohexanone.
Scheme 45: Griesbaum co-ozonolysis.
Scheme 46: Reactions of aryloxiranes 177a,b with oxygen.
Scheme 47: Intramolecular formation of 1,2,4-trioxolane 180.
Scheme 48: Formation of 1,2,4-trioxolane 180 by the reaction of 1,5-ketoacetal 181 with H2O2.
Scheme 49: 1,2,4-Trioxolane 186 with tetrazole fragment.
Scheme 50: 1,2,4-Trioxolane 188 with a pyridine fragment.
Scheme 51: 1,2,4-Trioxolane 189 with pyrimidine fragment.
Scheme 52: Synthesis of aminoquinoline-containing 1,2,4-trioxalane 191.
Scheme 53: Synthesis of arterolane.
Scheme 54: Oxidation of diarylheptadienes 197a–c with singlet oxygen.
Scheme 55: Synthesis of hexacyclinol peroxide 200.
Scheme 56: Oxidation of enone 201 and enenitrile 203 with singlet oxygen.
Scheme 57: Synthesis of 1,2-dioxanes 207 by oxidative coupling of carbonyl compounds 206 and alkenes 205.
Scheme 58: 1,2-Dioxanes 209 synthesis by co-oxidation of 1,5-dienes 208 and thiols.
Scheme 59: Synthesis of bicyclic 1,2-dioxanes 212 with aryl substituents.
Scheme 60: Isayama–Mukaiyama peroxysilylation of 1,5-dienes 213 followed by desilylation under acidic conditio...
Scheme 61: Synthesis of bicycle 218 with an 1,2-dioxane ring.
Scheme 62: Intramolecular cyclization with an oxirane-ring opening.
Scheme 63: Inramolecular cyclization with the oxetane-ring opening.
Scheme 64: Intramolecular cyclization with the attack on a keto group.
Scheme 65: Peroxidation of the carbonyl group in unsaturated ketones 228 followed by cyclization of hydroperox...
Scheme 66: CsOH and Et2NH-catalyzed cyclization.
Scheme 67: Preparation of peroxyplakoric acid methyl ethers A and D.
Scheme 68: Hg(OAc)2 in 1,2-dioxane synthesis.
Scheme 69: Reaction of 1,4-diketones 242 with hydrogen peroxide.
Scheme 70: Inramolecular cyclization with oxetane-ring opening.
Scheme 71: Inramolecular cyclization with MsO fragment substitution.
Scheme 72: Synthesis of 1,2-dioxane 255a, a structurally similar compound to natural peroxyplakoric acids.
Scheme 73: Synthesis of 1,2-dioxanes based on the intramolecular cyclization of hydroperoxides containing C=C ...
Scheme 74: Use of BCIH in the intramolecular cyclization.
Scheme 75: Palladium-catalyzed cyclization of δ-unsaturated hydroperoxides 271a–e.
Scheme 76: Intramolecular cyclization of unsaturated peroxyacetals 273a–d.
Scheme 77: Allyltrimethylsilane in the synthesis of 1,2-dioxanes 276a–d.
Scheme 78: Intramolecular cyclization using the electrophilic center of the peroxycarbenium ion 279.
Scheme 79: Synthesis of bicyclic 1,2-dioxanes.
Scheme 80: Preparation of 1,2-dioxane 286.
Scheme 81: Di(tert-butyl)peroxalate-initiated radical cyclization of unsaturated hydroperoxide 287.
Scheme 82: Oxidation of 1,4-betaines 291a–d.
Scheme 83: Synthesis of aminoquinoline-containing 1,2-dioxane 294.
Scheme 84: Synthesis of the sulfonyl-containing 1,2-dioxane.
Scheme 85: Synthesis of the amido-containing 1,2-dioxane 301.
Scheme 86: Reaction of singlet oxygen with the 1,3-diene system 302.
Scheme 87: Synthesis of (+)-premnalane А and 8-epi-premnalane A.
Scheme 88: Synthesis of the diazo group containing 1,2-dioxenes 309a–e.
Figure 4: Plakortolide Е.
Scheme 89: Synthesis of 6-epiplakortolide Е.
Scheme 90: Application of Bu3SnH for the preparation of tetrahydrofuran-containing bicyclic peroxides 318a,b.
Scheme 91: Application of Bu3SnH for the preparation of lactone-containing bicyclic peroxides 320a–f.
Scheme 92: Dihydroxylation of the double bond in the 1,2-dioxene ring 321 with OsO4.
Scheme 93: Epoxidation of 1,2-dioxenes 324.
Scheme 94: Cyclopropanation of the double bond in endoperoxides 327.
Scheme 95: Preparation of pyridazine-containing bicyclic endoperoxides 334a–c.
Scheme 96: Synthesis of 1,2,4-trioxanes 337 by the hydroperoxidation of unsaturated alcohols 335 with 1O2 and ...
Scheme 97: Synthesis of sulfur-containing 1,2,4-trioxanes 339.
Scheme 98: BF3·Et2O-catalyzed synthesis of the 1,2,4-trioxanes 342a–g.
Scheme 99: Photooxidation of enol ethers or vinyl sulfides 343.
Scheme 100: Synthesis of tricyclic peroxide 346.
Scheme 101: Reaction of endoperoxides 348a,b derived from cyclohexadienes 347a,b with 1,4-cyclohexanedione.
Scheme 102: [4 + 2]-Cycloaddition of singlet oxygen to 2Н-pyrans 350.
Scheme 103: Synthesis of 1,2,4-trioxanes 354 using peroxysilylation stage.
Scheme 104: Epoxide-ring opening in 355 with H2O2 followed by the condensation of hydroxy hydroperoxides 356 wi...
Scheme 105: Peroxidation of unsaturated ketones 358 with the H2O2/CF3COOH/H2SO4 system.
Scheme 106: Synthesis of 1,2,4-trioxanes 362 through Et2NH-catalyzed intramolecular cyclization.
Scheme 107: Reduction of the double bond in tricyclic peroxides 363.
Scheme 108: Horner–Wadsworth–Emmons reaction in the presence of peroxide group.
Scheme 109: Reduction of ester group by LiBH4 in the presence of 1,2,4-trioxane moiety.
Scheme 110: Reductive amination of keto-containing 1,2,4-trioxane 370.
Scheme 111: Reductive amination of keto-containing 1,2,4-trioxane and a Fe-containing moiety.
Scheme 112: Acid-catalyzed reactions of Н2О2 with ketones and aldehydes 374.
Scheme 113: Cyclocondensation of carbonyl compounds 376a–d using Me3SiOOSiMe3/CF3SO3SiMe3.
Scheme 114: Peroxidation of 4-methylcyclohexanone (378).
Scheme 115: Synthesis of symmetrical tetraoxanes 382a,b from aldehydes 381a,b.
Scheme 116: Synthesis of unsymmetrical tetraoxanes using of MeReO3.
Scheme 117: Synthesis of symmetrical tetraoxanes using of MeReO3.
Scheme 118: Synthesis of symmetrical tetraoxanes using of MeReO3.
Scheme 119: MeReO3 in the synthesis of symmetrical tetraoxanes with the use of aldehydes.
Scheme 120: Preparation of unsymmmetrical 1,2,4,5-tetraoxanes with high antimalarial activity.
Scheme 121: Re2O7-Catalyzed synthesis of tetraoxanes 398.
Scheme 122: H2SO4-Catalyzed synthesis of steroidal tetraoxanes 401.
Scheme 123: HBF4-Catalyzed condensation of bishydroperoxide 402 with 1,4-cyclohexanedione.
Scheme 124: BF3·Et2O-Catalyzed reaction of gem-bishydroperoxides 404 with enol ethers 405 and acetals 406.
Scheme 125: HBF4-Catalyzed cyclocondensation of bishydroperoxide 410 with ketones.
Scheme 126: Synthesis of symmetrical and unsymmetrical tetraoxanes 413 from benzaldehydes 412.
Scheme 127: Synthesis of bridged 1,2,4,5-tetraoxanes 415a–l from β-diketones 414a–l and H2O2.
Scheme 128: Dimerization of zwitterions 417.
Scheme 129: Ozonolysis of verbenone 419.
Scheme 130: Ozonolysis of O-methyl oxime 424.
Scheme 131: Peroxidation of 1,1,1-trifluorododecan-2-one 426 with oxone.
Scheme 132: Intramolecular cyclization of dialdehyde 428 with H2O2.
Scheme 133: Tetraoxanes 433–435 as by-products in peroxidation of ketals 430–432.
Scheme 134: Transformation of triperoxide 436 in diperoxide 437.
Scheme 135: Preparation and structural modifications of tetraoxanes.
Scheme 136: Structural modifications of steroidal tetraoxanes.
Scheme 137: Synthesis of 1,2,4,5-tetraoxane 454 containing the fluorescent moiety.
Scheme 138: Synthesis of tetraoxane 458 (RKA182).
Total synthesis of (−)-epimyrtine by a gold-catalyzed hydroamination approach
- Thi Thanh Huyen Trinh,
- Khanh Hung Nguyen,
- Patricia de Aguiar Amaral and
- Nicolas Gouault
Beilstein J. Org. Chem. 2013, 9, 2042–2047, doi:10.3762/bjoc.9.242
- of (−)-epimyrtine have been described to date including the intramolecular allylsilane N-acyliminium ion cyclization [6], the organocatalytic aza-Michael reaction [7], the intramolecular Mannich reaction [8], and the iminium ion cascade reaction [9][10]. More efficient, convenient and highly
Graphical Abstract
Scheme 1: Previously reported approach from β-aminoynones for the synthesis of pyridones.
Scheme 2: Retrosynthetic analysis of (−)-epimyrtine.
Scheme 3: Synthesis of (−)-epimyrtine.
The chemistry of amine radical cations produced by visible light photoredox catalysis
- Jie Hu,
- Jiang Wang,
- Theresa H. Nguyen and
- Nan Zheng
Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234
- 15 by abstraction of a hydrogen atom directly. The addition of the enol form of α-ketoester 59 to 15 furnishes the Mannich adduct 60. A retro-aza-Michael reaction via enol 61 allows cleavage of the C–N bond to yield secondary aniline 62. Aniline 62 is first oxidized to imine 63, which is further
- independently discovered that the efficiency of the same Michael reaction was greatly improved in the presence of a Brønsted acid (Scheme 23) [90]. Some of the improvements included shorter reaction time, higher yields, and use of a weaker light source (CFL). The most effective acid catalysts, of which TFA was
Graphical Abstract
Scheme 1: Amine radical cations’ mode of reactivity.
Scheme 2: Reductive quenching of photoexcited Ru complexes by Et3N.
Scheme 3: Photoredox aza-Henry reaction.
Scheme 4: Formation of iminium ions using BrCCl3 as stoichiometric oxidant.
Scheme 5: Oxidative functionalization of N-aryltetrahydroisoquinolines using Eosin Y.
Scheme 6: Synthetic and mechanistic studies of Eosin Y-catalyzed aza-Henry reaction.
Scheme 7: Oxidative functionalization of N-aryltetrahydroisoquinolines using RB and GO.
Scheme 8: Merging Ru-based photoredox catalysis and Lewis base catalysis for the Mannich reaction.
Scheme 9: Merging Au-based photoredox catalysis and Lewis base catalysis for the Mannich reaction.
Scheme 10: Merging Ru-based photoredox catalysis and Cu-catalyzed alkynylation reaction.
Scheme 11: Merging Ru-based photoredox catalysis and NHC catalysis.
Scheme 12: 1,3-Dipolar cycloaddition of photogenically formed azomethine ylides.
Scheme 13: Plausible mechanism for photoredox 1,3-dipolar cycloaddition.
Scheme 14: Photoredox-catalyzed cascade reaction for the synthesis of fused isoxazolidines.
Scheme 15: Plausible mechanism for the photoredox-catalyzed cascade reaction.
Scheme 16: Photoredox-catalyzed α-arylation of glycine derivatives.
Scheme 17: Photoredox-catalyzed α-arylation of amides.
Scheme 18: Intramolecular interception of iminium ions by sulfonamides.
Scheme 19: Intramolecular interception of iminium ions by alcohols and sulfonamides.
Scheme 20: Intermolecular interception of iminium ions by phosphites.
Scheme 21: Photoredox-catalyzed oxidative phosphonylation by Eosin Y.
Scheme 22: Conjugated addition of α-amino radicals to Michael acceptors.
Scheme 23: Conjugated addition of α-amino radicals to Michael acceptors assisted by a Brønsted acid.
Scheme 24: Conjugated addition of α-amino radicals derived from anilines to Michael acceptors.
Scheme 25: Oxygen switch between two pathways involving α-amino radicals.
Scheme 26: Interception of α-amino radicals by azodicarboxylates.
Scheme 27: α-Arylation of amines.
Scheme 28: Plausible mechanism for α-arylation of amines.
Scheme 29: Photoinduced C–C bond cleavage of tertiary amines.
Scheme 30: Photoredox cleavage of C–C bonds of 1,2-diamines.
Scheme 31: Proposed mechanism photoredox cleavage of C–C bonds.
Scheme 32: Intermolecular [3 + 2] annulation of cyclopropylamines with olefins.
Scheme 33: Proposed mechanism for intermolecular [3 + 2] annulation.
Scheme 34: Photoinduced clevage of N–N bonds of aromatic hydrazines and hydrazides.
Efficient synthesis of β’-amino-α,β-unsaturated ketones
- Isabelle Abrunhosa-Thomas,
- Aurélie Plas,
- Nishanth Kandepedu,
- Pierre Chalard and
- Yves Troin
Beilstein J. Org. Chem. 2013, 9, 486–495, doi:10.3762/bjoc.9.52
- devised for the asymmetric synthesis of β’-amino-protected-α,β enones, a valuable intermediate for the synthesis of trans 2,6-disubstituted piperidines. The scope and limitation of the aza-Michael reaction were studied with a range of substrates. We are currently working on the application of this
Graphical Abstract
Scheme 1: Asymmetric synthesis of 2-methyl-6-phenyl piperidine.
Scheme 2: (a) Davies amine, BuLi, THF, −78 °C; dr ≥ 94% ; (b) H2, Pd(OH)2, MeOH; (c) Na2CO3, PhCH2CO2Cl, CH2Cl...
Scheme 3: Modified synthetic route to15.
Scheme 4: Possible pathways to obtain phosphonate 13 (a) Davies amine, BuLi, THF, −78 °C; dr ≥ 95%; (b) H2, P...
Scheme 5: Synthesis of compound 14.
Scheme 6: General synthesis of compound 13 (a) Davies amine, BuLi, THF, −78 °C; (b) H2, Pd(OH)2/C, MeOH; (c) ...
Scheme 7: Optimization of conditions for the Horner–Wadsworth–Emmons reaction.
Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives
- Ishmael B. Masesane and
- Zelalem Yibralign Desta
Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244
- 60. However, the reaction suffered from very poor yields (15–21%). The reaction is thought to proceed through the condensation of aldehyde 60 and prolinol 61 to give a chiral iminium-ion intermediate. This intermediate then undergoes a domino reaction involving a Michael reaction with salicylaldehyde
Graphical Abstract
Scheme 1: Retrosynthetic analysis of chromane 1.
Scheme 2: General reaction of salicylaldehyde (5) and acetophenone (7) in the synthesis of flavan 10 and flav...
Scheme 3: Synthesis of flavan 16 by Xue and co-workers.
Scheme 4: Synthesis of flavans of type 10 by Mazimba and co-workers.
Scheme 5: Sashidhara and co-workers synthesis of flavone (11).
Scheme 6: Synthesis of chromane derivative 19 by Yu-Ling and co-workers.
Scheme 7: Synthesis of 2-iminochromene 21 by Costa and co-workers.
Scheme 8: Synthesis of 2-aminochromene 22 by Costa and co-workers.
Scheme 9: Costa and co-workers used Et3N in the synthesis of 2-aminochromene 24.
Scheme 10: Synthesis of 2-aminochromene 27 by Shanthi and co-workers.
Scheme 11: Enantioselective synthesis of 2-aminochromenes 32–34 by Yang and co-workers.
Scheme 12: Synthesis of 2-iminochromene derivatives of type 36 by Kovalenko and co-workers.
Scheme 13: Synthesis of 2-aminochromenes 22 and 37 by Ghorbani-Vaghei and co-workers.
Scheme 14: Synthesis of 2-aminochromene 39 by Yu and co-workers.
Scheme 15: Synthesis of 2-iminochromene 21 by Heravi and co-workers.
Scheme 16: Tandem reaction of salicylaldehyde and α,β-unsaturated compounds.
Scheme 17: Kawase and co-workers synthesis of 2,2-dimethylchromene 45.
Scheme 18: Synthesis of 2,3-disubstituted chromene 47 by Stukan and co-workers.
Scheme 19: Ravichandrans synthesis of 3-substituted chromenes 52–55.
Scheme 20: Synthesis of 3-substituted chromene 58 coumarin 59 by Paye and co-workers.
Scheme 21: Govender and co-workers asymmetric synthesis of 2-phenylchromenes 62 and 63.
Scheme 22: Asymmetric synthesis of 2-phenylchromene 62 by Li and co-workers.
Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach
- Pankaj Chauhan and
- Swapandeep Singh Chimni
Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240
- enantioselectivity (56–86% ee). The reactions carried out under HSBM afford (S)-3-hydroxyindole with higher enantioselectivity, relative to the reaction performed under traditional stirring in solvent. Michael reaction The asymmetric organocatalytic Michael addition to various unsaturated acceptors is one of the
- ball-milling conditions. O-Lauroyl-trans-4-hydroxyproline (VII) was identified as the best catalyst in aqueous media, whilst α,α-diphenylprolinol trimethylsilyl ether (VIII) turned out to be the best catalyst under ball-milling conditions. Michael reaction of aliphatic aldehydes 6 with nitroalkenes 7
- with conventional stirring, because when the reaction was carried out by conventional stirring, the product yield and stereoselectivity deteriorated significantly. Xu and co-workers reported a highly enantioselective organocatalytic Michael reaction of 1,2-carbonyl compounds to nitro-olefins under
Graphical Abstract
Scheme 1: Proline-catalysed aldol reaction in a ball-mill.
Scheme 2: Proline-catalysed aldol reaction between solid substrates (1b and 2a).
Scheme 3: (S)-Binam-L-prolinamide catalysed asymmetric aldol reaction by using a ball-mill. aConversion.
Scheme 4: Asymmetric aldol reaction assisted by ball-milling catalysed by dipeptides (A) with III and (B) wit...
Scheme 5: Thiodipeptide-catalysed asymmetric aldol reaction of (A) ketones with aldehydes and (B) acetone wit...
Scheme 6: Enantioselective Michael reaction of aldehydes with nitroalkenes catalysed by pyrrolidine-derived o...
Scheme 7: Chiral squaramide catalysed asymmetric Michael reaction assisted by ball-milling.
Scheme 8: Asymmetric organocatalytic Michael reaction assisted by pestle and mortar grinding.
Scheme 9: C-2 symmetric thiourea catalysed enantioselective MBH reaction.
Scheme 10: Quinine-catalysed ring opening of meso-anhydride by ball-milling.
Scheme 11: Ball-milling-assisted (A) synthesis of glycine schiff bases and (B) their organocatalytic asymmetri...
Scheme 12: Enantioselective amination of β-ketoester by using pestle and mortar.
Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines
- Chittaranjan Bhanja,
- Satyaban Jena,
- Sabita Nayak and
- Seetaram Mohapatra
Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191
- high yield (up to 90%) and enantioselectivity (up to 99%), whereas compound 2 having electron-withdrawing groups provided poor results. Very recently, Xu et al. [46] reported an improved protocol for the domino-oxa-Michael reaction of salicylaldehydes 1 with α,β-unsaturated aldehydes 2 employing
- ).The protocol involved a tandem oxa-Michael–Michael reaction of 3-methyl-but-2-enal (22) and (E)-2-(2-nitrovinyl)-benzene-1,4-diol (21) followed by a domino Michael–aldol condensation with aldehyde 24 in the presence of TMS-protected diphenylprolinol Ib/AcOH as catalyst, affording the hexahydro-6H
- %) (Scheme 31). In this cascade reaction, the installation of electron-withdrawing groups on the amino moiety of 2-aminobenzaldehydes is anticipated to increase the aniline N–H acidity, the abstraction of which by the tertiary amine leads to an aza-Michael reaction. The thiourea group in the chiral catalyst
Graphical Abstract
Figure 1: Some representative molecules having chromene, thiochromene or 1,2-dihydroquinolin structural motif...
Figure 2: Screened chiral proline and its derivatives as organocatalysts. Rb = rubidium.
Figure 3: Screened chiral bifunctional thiourea, its derivatives, cinchona alkaloids and other organocatalyst...
Scheme 1: Diarylprolinolether-catalyzed tandem oxa-Michael–aldol reaction reported by Arvidsson.
Scheme 2: Tandem oxa-Michael–aldol reaction developed by Córdova.
Scheme 3: Domino oxa-Michael-aldol reaction developed by Wei and Wang.
Scheme 4: Chiral amine/chiral acid catalyzed tandem oxa-Michael–aldol reaction developed by Xu et al.
Scheme 5: Modified diarylproline ether as amino catalyst in oxa-Michael–aldol reaction as reported by Xu and ...
Scheme 6: Chiral secondary amine promoted oxa-Michael–aldol cascade reactions as reported by Wang and co-work...
Scheme 7: Reaction of salicyl-N-tosylimine with aldehydes by domino oxa-Michael/aza-Baylis–Hillman reaction, ...
Scheme 8: Silyl prolinol ether-catalyzed oxa-Michael–aldol tandem reaction of alkynals with salicylaldehydes ...
Scheme 9: Oxa-Michael–aldol sequence for the synthesis of tetrahydroxanthones developed by Córdova.
Scheme 10: Synthesis of tetrahydroxanthones developed by Xu.
Scheme 11: Diphenylpyrrolinol trimethylsilyl ether catalyzed oxa-Michael–Michael–Michael–aldol reaction for th...
Scheme 12: Enantioselective cascade oxa-Michael–Michael reaction of alkynals with 2-(E)-(2-nitrovinyl)-phenols...
Scheme 13: Domino oxa-Michael–Michael–Michael–aldol reaction of 2-(2-nitrovinyl)-benzene-1,4-diol with α,β-uns...
Scheme 14: Tandem oxa-Michael–Henry reaction catalyzed by organocatalyst and salicylic acid, as reported by Xu....
Scheme 15: Asymmetric synthesis of nitrochromenes from salicylaldehydes and β-nitrostyrene, as reported by San...
Scheme 16: Domino Michael–aldol reaction between salicyaldehydes with β-nitrostyrene, as reported by Das and c...
Scheme 17: Enantioselective synthesis of 2-aryl-3-nitro-2H-chromenes, as reported by Schreiner.
Scheme 18: (S)-diphenylpyrrolinol silyl ether-promoted cascade thio-Michael–aldol reactions, as reported by Wa...
Scheme 19: Organocatalytic asymmetric domino Michael–aldol condensation of mercaptobenzaldehyde and α,β-unsatu...
Scheme 20: Organocatalytic asymmetric domino Michael–aldol condensation between mercaptobenzaldehyde and α,β-u...
Scheme 21: Hydrogen-bond-mediated Michael–aldol reaction of 2-mercaptobenzaldehyde with α,β-unsaturated oxazol...
Scheme 22: Domino Michael–aldol reaction of 2-mercaptobenzaldehydes with maleimides catalyzed by cinchona alka...
Scheme 23: Domino thio-Michael–aldol reaction between 2-mercaptoacetophenone and enals developed by Córdova an...
Scheme 24: Enantioselective tandem Michael–Henry reaction of 2-mercaptobenzaldehyde with β-nitrostyrenes repor...
Scheme 25: Enantioselective tandem Michael–Knoevenagel reaction between 2-mercaptobenzaldehydes and benzyliden...
Scheme 26: Cinchona alkaloid thiourea catalyzed Michael–Michael cascade reaction, as reported by Wang and co-w...
Scheme 27: Domino aza-Michael–aldol reaction between 2-aminobenzaldehydes and α,β-unsaturated aldehydes, as re...
Scheme 28: (S)-Diphenylprolinol TES ether-promoted aza-Michael–aldol cascade reaction, as developed by Wang’s ...
Scheme 29: Domino aza-Michael–aldol reaction reported by Hamada.
Scheme 30: Organocatalytic asymmetric synthesis of 3-nitro-1,2-dihydroquinolines by a dual activation protocol...
Scheme 31: Asymmetric synthesis of 3-nitro-1,2-dihydroquinolines by cascade aza-Michael–Henry–dehydration reac...
Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity
- Tatyana E. Shubina,
- Matthias Freund,
- Sebastian Schenker,
- Timothy Clark and
- Svetlana B. Tsogoeva
Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168
- produces the Michael product 15 with 66% yield in only 2 h. We therefore decided to study the solvent effects on the reaction outcome in the nitro-Michael reaction of diethylmalonate with trans-β-nitrostyrene further. The results are shown in Table 1. Whereas Michael reactions performed in dichloromethane
- systems, we decided to carry out a computational investigation of this guanidine-thiourea catalysed nitro-Michael reaction employing density functional calculations. Theoretical studies: DFT calculations The main goal of our calculations was to gain insight into the mechanism of the nitro-Michael addition
- not considered for the further studies. A similar Michael reaction of 1,3-dicarbonyl compounds with nitroolefins has been studied in some detail before [57][59]. It is generally proposed that the reaction proceeds first by deprotonation of the acidic proton of malonate 14 followed by formation of a
Graphical Abstract
Scheme 1: Synthesis of guanidine-thiourea organocatalyst 7.
Scheme 2: Henry reaction of 3-phenylpropionaldehyde (8) with nitromethane (9).
Scheme 3: Michael addition of (12) and (14) to trans-β-nitrostyrene (11).
Figure 1: Optimized geometries of four conformers of catalyst 7. Energies are in kcal·mol−1, B3PW91/6–31G(d) ...
Scheme 4: Energy profile for the first step of the reaction between catalyst 7 and malonate 14. Energies are ...
Figure 2: Complexes (CatN1–CatN5) between catalyst 7 and nitrostyrene 11. Energies are in kcal·mol−1, B3PW91/...
Scheme 5: Two possible routes for ternary complex formation. Energies are in kcal·mol−1, B3PW91/6–31G(d) (fir...
Figure 3: Geometries of transition states for R and S products. Relative energies (with respect to Init10) ar...
Figure 4: Geometries of transition states for R and S products. Relative energies (with respect to Init10) ar...
Figure 5: B3PW91/6–31G(d) (first entry), DFT-PCM (second entry), MP2/6–31G(d)//B3PW91/6–31G(d) (third entry) ...
Figure 6: Geometries of transition states for R and S products with 7-TABD catalyst. Relative energies (to In...
Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones
- Sergei Žari,
- Tiiu Kailas,
- Marina Kudrjashova,
- Mario Öeren,
- Ivar Järving,
- Toomas Tamm,
- Margus Lopp and
- Tõnis Kanger
Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165
- calculated VCD spectra of the reaction product 3a. Keywords: Michael addition; non-covalent catalysis; organocatalysis; squaramide; thiourea; Introduction The asymmetric 1,4-conjugated addition (Michael reaction) of C-nucleophiles to enones is a powerful tool for obtaining a significant variety of
Graphical Abstract
Figure 1: The conjugated addition to unsaturated 1,4-diketone 1.
Figure 2: Organocatalysts screened.
Figure 3: Proposed transition state.
Figure 4: Calculated (red) and experimental (blue) IR (A) and VCD spectrum (B) of compound (R)-3a.
Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles
- Pavol Jakubec,
- Dane M. Cockfield,
- Madeleine Helliwell,
- James Raftery and
- Darren J. Dixon
Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64
- with the generally high diastereocontrol in the formation of piperidinones 1a–j and 2a–l is interesting and worthy of further commentary. With the knowledge that the retro-Michael reaction does not occur under standard reaction conditions (Scheme 4) and assuming that the final step of the cascade (the
Graphical Abstract
Figure 1: Biologically active natural products and drugs containing the piperidine ring.
Scheme 1: A general strategy to 5-nitropiperidin-2-ones and related heterocycles.
Scheme 2: The synthesis of Michael adduct model substrates for the nitro-Mannich/lactamisation cascade.
Scheme 3: Nitro-Mannich/lactamisation cascade with in situ formed imines.
Figure 2: Cyclic imines employed in nitro-Mannich/lactamisation cascade.
Scheme 4: Nitro-Mannich/lactamisation cascade of diastereomeric Michael adducts 6a, 6a’’ with cyclic imine 5a....
Scheme 5: Nitro-Mannich/lactamisation cascade with cyclic imines. aDiastereomeric ratio in a crude reaction m...
Scheme 6: Possible explanations for the observed high stereoselectivities in the nitro-Mannich/lactamisation ...
Scheme 7: Thermodynamically-driven epimerisation of 5-nitropiperidin-2-ones 2m and 2m’.
Figure 3: Thermodynamically driven epimerisation of 5-nitropiperidin-2-ones 2m and 2m’; identical diastereome...
Scheme 8: One-pot three/four-component enantioselective Michael addition/nitro-Mannich/lactamisation cascade.
Scheme 9: Protodenitration of 5-nitropiperidin-2-ones.
Scheme 10: Various reductions of denitrated heterocycles.
Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method
- Zong-Bo Xie,
- Na Wang,
- Ming-Yu Wu,
- Ting He,
- Zhang-Gao Le and
- Xiao-Qi Yu
Beilstein J. Org. Chem. 2012, 8, 534–538, doi:10.3762/bjoc.8.61
- ). Some aromatic 1,3-dicarbonyl compounds were also successfully used as donors in this Michael reaction in moderate to good yields (Table 1, entries 18–21). In addition, furylnitrostyrene (1m) reacted with 1,3-cyclopentanedione (2a) as well as furan-2,4(3H,5H)-dione (2b) to give the corresponding
Graphical Abstract
Scheme 1: Michael addition under catalyst- and solvent-free conditions.
Figure 1: The grinding effect of different grinding aids. Conditions: β-nitrostyrene (14.9 mg, 0.1 mmol), 1,3...
Figure 2: Yields of the model reaction in different solvents. Conditions: β-nitrostyrene (14.9 mg, 0.1 mmol),...
Figure 3: The effect of the amount of quartz sand on the yield. Conditions: β-nitrostyrene (14.9 mg, 0.1 mmol...
Synthesis and characterization of new diiodocoumarin derivatives with promising antimicrobial activities
- Hany M. Mohamed,
- Ashraf H. F. Abd EL-Wahab,
- Ahmed M. EL-Agrody,
- Ahmed H. Bedair,
- Fathy A. Eid,
- Mostafa M. Khafagy and
- Kamal A. Abd-EL-Rehem
Beilstein J. Org. Chem. 2011, 7, 1688–1696, doi:10.3762/bjoc.7.199
- -diiodosalicylaldehyde; diethyl malonate; ethyl cyanoacetate; coumarins; Michael reaction; Introduction Coumarins and their derivatives are biologically and pharmaceutically interesting compounds known for their use as additives in food, perfumes, cosmetics, pharmaceuticals, platelet aggregation and agrochemicals [1][2
- -withdrawing carbonyl groups, the behavior of 1 towards activated methylene compounds under Michael reaction conditions was investigated. Thus, treatment of 1 with ethyl cyanoacetate/NH4OAc in boiling ethanol afforded two reaction products. The insoluble reaction product was identified as ethyl 2-(3-carbamoyl
- Michael reaction conditions to yield a cyclic Michael adduct, which underwent hydrolysis by NH3 or MeNH2 and cyclization through the elimination of H2O (Scheme 5). The structure of compound 14a was established by 13C NMR, which showed δ at 42.5 (CH2(c)), 168.4 cm–1 (CONH), and 170 cm–1 (CO). The
Graphical Abstract
Scheme 1: Synthesis of 6,8-diiodocoumarin derivatives 1–7.
Scheme 2: Proposed fragmentation pathways for the EI ions of the substituted 6,8-diiodocoumarins 3 and 7.
Scheme 3: Synthesis of 6,8-diiodocoumarin-3-N-carboxamide derivatives 8–11.
Scheme 4: Synthesis of ethyl cyanoacetate and pyridine derivatives 12 and 13.
Scheme 5: Synthesis of 1,3-oxazocine derivatives 14a,b.
Figure 1: Graphical representation of the antibacterial activity of tested compounds compared to ampicillin.
Figure 2: Graphical representation of antifungal activity of tested compounds, compared to calforan.
Efficient gold(I)/silver(I)-cocatalyzed cascade intermolecular N-Michael addition/intramolecular hydroalkylation of unactivated alkenes with α-ketones
- Ya-Ping Xiao,
- Xin-Yuan Liu and
- Chi-Ming Che
Beilstein J. Org. Chem. 2011, 7, 1100–1107, doi:10.3762/bjoc.7.126
- simple starting materials [41]. We initially envisioned that the gold(I)-catalyzed cascade process could be established starting from the intermolecular N-Michael reaction of α,β-unsaturated ketone 1 and substituted allylamine 2 to furnish an α-ketone intermediate I [42][43][44] (for gold-catalyzed
- intramolecular N-Michael reaction see [42][43]), which further undergoes a subsequent gold(I)-catalyzed hydroalkylation to give pyrrolidine compounds 3 (Scheme 1); these compounds are versatile synthetic building blocks for organic synthesis and are important structural elements of many therapeutic drug
- of the intermolecular N-Michael reaction. Upon subsequent treatment of phenyl vinyl ketone (1a) with N-tosylallylamine (2a) in the presence of 10 mol % of AgClO4 at 90 °C for 3 h, the α-ketone intermediate 4 was formed in 85% yield, however, no product 3a was observed. Even after a longer reaction
Graphical Abstract
Scheme 1: Cascade intermolecular N-Michael addition/intramolecular hydroalkylation of unactivated alkenes wit...
Scheme 2: Some control experiments.
Scheme 3: The reaction pathway.
Single enantiomer synthesis of α-(trifluoromethyl)-β-lactam
- Václav Jurčík,
- Alexandra M. Z. Slawin and
- David O'Hagan
Beilstein J. Org. Chem. 2011, 7, 759–766, doi:10.3762/bjoc.7.86
- explored for the hydrogenolysis of 5a, however cleavage of the C–N bond proved very difficult and a satisfactory method could not be found. Therefore, (S)-α-(p-methoxyphenyl)ethylamine (3b) was explored as an alternative amine for the aza-Michael reaction, as removal of this amine using ceric ammonium
- nitrate (CAN) oxidation offered a milder deprotection method [15]. The aza-Michael reaction proved straightforward to generate 4b and then cyclisation again using thionyl chloride and triethylamine gave β-lactams 5b in a 40% de, presumably again a thermodynamically biased isomer ratio. The
Graphical Abstract
Figure 1: Enantiomers of α-(trifluoromethyl)-β-lactam (1).
Scheme 1: Synthetic route involving a diastereoisomeric separation to α-(trifluoromethyl)-β-lactam ((S)-1) fr...
Figure 2: X-ray structures of (a) β-lactam (S)-1 and (b) (αR,3R)-5c. (a) Determination of the absolute stereo...
Scheme 2: Synthesis of stereoisomers 5c. The stereochemistry of the major isomer (αR,3R)-5c was solved by X-r...
