Enantioselective Activation of Stable Carboxylate Esters as Enolate Equivalents <i>via</i> N-Heterocyclic Carbene Catalysts
Organic LettersPublished 9 April 2012
Hao Lin, Yu Du, Hui Lv, Xingkuan Chen, Huishen Jiang, Yaling Shao
Citations203
SJR quartileQ1
SJR score1.24
SNIP1.03
Generate an AI Snapshot to get a quick, structured summary of this paper.
Study Snapshot
ObjectiveStudy objective
MethodsResearch methodology
PopulationPopulation studied
Sample sizeSample sizes
OutcomesStudy outcomes here
ResultsStudy results comes here
LimitationsResearch study limitations comes here
A concise AI-generated summary of the paper will appear here once you click Generate AI Snapshot.
TL;DR
The first N-Heterocyclic Carbene (NHC) mediated activation of stable carboxylate esters to generate enolate intermediates is disclosed, which undergo enantioselective reactions with α,β-unsaturated imines.
Abstract
The first N-Heterocyclic Carbene (NHC) mediated activation of stable carboxylate esters to generate enolate intermediates is disclosed. The catalytically generated arylacetic ester enolates undergo enantioselective reactions with α,β-unsaturated imines.
Keywords
Chemistry
Chemical ReviewsOrganocatalysis by N-Heterocyclic Carbenes
3,014 Citations2007Dieter Enders, Oliver Niemeier +1 more
The inversion of the classical reactivity (Umpolung) opens up new synthetic pathways in biochemical processes as nucleophilic acylations and in nature, the coenzyme thiamine (vitamin B1), a natural thiazolium salt, utilizes a catalytic variant of this concept in biochemical process as nucleophile acylation.
Chemical ReviewsAsymmetric Enamine Catalysis
2,830 Citations2007Santanu Mukherjee, Jung Woon Yang +2 more
Angewandte Chemie International EditionN‐Heterocyclic Carbenes as Organocatalysts
1,438 Citations2007Nicolas Marion, Silvia Díez‐González +1 more
This work highlights the ever-increasing number of reactions that can be promoted by N-heterocyclic carbenes and investigates the role of benzoin condensation in these reactions.
Accounts of Chemical ResearchNucleophilic Carbenes in Asymmetric Organocatalysis
1,040 Citations2004Dieter Enders, Tim Balensiefer
After a long and difficult search, stable carbenes are finally isolated, characterized, and in the chemist's hands, and the experiments of decades have finally resulted in successful enantioselective benzoin condensations and enantiOSElective intramolecular Stetter reactions.
Angewandte Chemie International EditionN‐Heterocyclic Carbene Catalyzed Domino Reactions
980 Citations2011André Grossmann, Dieter Enders
A critical consideration of domino, cascade, and tandem catalysis in the case of N-heterocyclic carbenes catalysts is presented and recent publications in this area are highlighted.
Chemical ReviewsEnantioselective Amino Acid Synthesis by Chiral Phase-Transfer Catalysis
827 Citations2003Keiji Maruoka, Takashi Ooi
Accounts of Chemical ResearchExtending NHC-Catalysis: Coupling Aldehydes with Unconventional Reaction Partners
764 Citations2011Akkattu T. Biju, Nadine Kuhl +1 more
An efficient intermolecular Stetter reaction is developed for the formation of α-amino acid derivatives, with broad aldehyde scope and high enantiomeric excess, and tailor-made thiazolylidene catalysts allowed the unprecedented use of nonactivated olefins and alkynes as aldehydes coupling partners.
Chemical Society ReviewsRecent advances in carbon–carbon bond-forming reactions involving homoenolates generated by NHC catalysis
642 Citations2008Vijay Nair, Sreekumar Vellalath +1 more
The versatility of NHC-bound homoenolate is illustrated by its annulation with various carbonyl compounds leading to gamma-butyrolactones, spiro-gamma- butyrolactsones, and delta-lactones.
Chemical Society ReviewsEmploying homoenolates generated by NHC catalysis in carbon–carbon bond-forming reactions: state of the art
592 Citations2011Vijay Nair, Rajeev S. Menon +5 more
This tutorial review focuses on these and other types of homoenolate reactions reported recently, and in the process, updates the previous account published in 2008 in this journal.
Journal of the American Chemical SocietyHighly Enantioselective Azadiene Diels−Alder Reactions Catalyzed by Chiral N-Heterocyclic Carbenes
579 Citations2006Ming He, Justin R. Struble +1 more
In contrast to uncatalyzed variants, this organocatalytic process proceeds at room temperature without stoichiometric reagents, producing synthetically valuable, enantiomerically pure cis-3,4-disubstituted dihydropyridinone products.
Chemical ReviewsNucleophilic Chiral Amines as Catalysts in Asymmetric Synthesis
508 Citations2003Stefan France, David Guérin +2 more
This paper presents Kinetic Resolution of Alcohols and Amines and Catalysis on Sequentially-Linked Columns, a large-scale study of single-crystal catalysis, which aims at determining the carrier and removal status of Amines in response to alcohol.
Journal of the American Chemical SocietyNHC Catalyzed Oxidations of Aldehydes to Esters: Chemoselective Acylation of Alcohols in Presence of Amines
493 Citations2010Suman De Sarkar, Stefan Grimme +1 more
Accounts of Chemical ResearchAsymmetric Catalysis with “Planar-Chiral” Derivatives of 4-(Dimethylamino)pyridine
465 Citations2004Gregory C. Fu
"planar-chiral" derivatives of 4-(dimethylamino)pyridine (DMAP) are developed, a highly versatile nucleophilic catalyst that are effective in a diverse array of processes, including the Staudinger synthesis of beta-lactams, the acylation of silyl ketene acetals, and the kinetic resolution of amines.
Chemical ScienceCooperative Lewis acid/N-heterocyclic carbene catalysis
463 Citations2011Daniel T. Cohen, Karl A. Scheidt
The incorporation of a Lewis acid into Brønsted base-catalyzed conjugate addition allowed for an increase in yields and enhancement of the reactivity, reversal of the diastereo- or regioselectivity, and activation of previously inactive electrophiles.
Accounts of Chemical ResearchEnantioselective Nucleophilic Catalysis with “Planar-Chiral” Heterocycles
443 Citations2000Gregory C. Fu
Angewandte Chemie International EditionExtending Mechanistic Routes in Heterazolium Catalysis–Promising Concepts for Versatile Synthetic Methods
394 Citations2005Kirsten Zeitler
Journal of the American Chemical SocietyConversion of α-Haloaldehydes into Acylating Agents by an Internal Redox Reaction Catalyzed by Nucleophilic Carbenes
383 Citations2004Nathan T. Reynolds, Javier Read de Alaniz +1 more
It is reported that treatment of an alpha-haloaldehyde with a nucleophile in the presence of catalytic amounts of nucleophilic carbenes results in an internal redox reaction giving rise to a dehalogenated acylating agent as an intermediate by a new reaction manifold.
Journal of the American Chemical SocietyNucleophilic Carbene and HOAt Relay Catalysis in an Amide Bond Coupling: An Orthogonal Peptide Bond Forming Reaction
368 Citations2007Harit U. Vora, Tomislav Rovis
A catalyzed internal redox process provides a route from α- reducible aldehydes and amines to α-reduced amides and proceeds in excellent yields using a variety of primary and secondary alkyl and aryl amines.
Organic LettersN-Heterocyclic Carbenes as Versatile Nucleophilic Catalysts for Transesterification/Acylation Reactions
352 Citations2002Gabriela A. Grasa, Rebecca M. Kissling +1 more
Imidazol-2-ylidenes, a family of N-heterocyclic carbenes (NHC), are efficient catalysts in the transesterification between esters and alcohols and form efficiently the corresponding esters in very short reaction times.
Journal of the American Chemical SocietyN-Heterocyclic Carbene-Catalyzed Redox Amidations of α-Functionalized Aldehydes with Amines
350 Citations2007Jeffrey W. Bode, Stephanie S. Sohn
Organic LettersChiral N-Heterocyclic Carbene Catalyzed Staudinger Reaction of Ketenes with Imines: Highly Enantioselective Synthesis of <i>N</i>-Boc β-Lactams
348 Citations2007Yanrong Zhang, Lin He +3 more
N-heterocyclic carbenes were demonstrated to be efficient catalysts for the Staudinger reaction of ketenes with N-tosyl, N-benzyloxycarbonyl, or N-tert-butoxy Carbonyl imines, and two possible catalytic pathways, initiated by the addition of NHC to ketenes or imines were discussed.
Chemical ReviewsChiral Dialkylaminopyridine Catalysts in Asymmetric Synthesis
334 Citations2007Ryan P. Wurz
Journal of the American Chemical SocietyChiral N-Heterocyclic Carbene Catalyzed, Enantioselective Oxodiene Diels−Alder Reactions with Low Catalyst Loadings
332 Citations2006Ming He, Gerson J. Uc +1 more
Chiral N-heterocyclic carbene catalyzed redox reactions of racemic alpha-chloroaldehydes lead to the generation of chiral enolates suitable for highly enantioselective inverse-electron-demand 1-oxodiene Diels-Alder reactions.
Organic LettersExpanding the Catalytic Activity of Nucleophilic N-Heterocyclic Carbenes for Transesterification Reactions
328 Citations2002G.W. Nyce, Jorge A. Lamboy +3 more
The use of nucleophilic N-heterocyclic carbenes as efficient transesterification catalysts were found to be mild, selective, and more active than traditional organic nucleophiles.
Chemical ReviewsRecent Developments in the Use of Catalytic Asymmetric Ammonium Enolates in Chemical Synthesis
321 Citations2007Matthew J. Gaunt, Carin C. C. Johansson
This review details the recent development of methods that use chiral tertiary amine catalysts as a source to generate asymmetric ammonium enolates, which often require more complex synthesis and often display enhanced reactivity compared to their cinchona alkaloid counterparts.
Journal of the American Chemical SocietyCatalytic Generation of Activated Carboxylates: Direct, Stereoselective Synthesis of β-Hydroxyesters from Epoxyaldehydes
313 Citations2004Kenneth Yu‐Kin Chow, Jeffrey W. Bode
This chemistry unveils a mechanistically viable solution to the catalytic, waste-free synthesis of esters, and provides a new method for the synthesis of anti-aldol adducts.
Journal of the American Chemical Society<i>N</i>-Heterocyclic Carbene-Catalyzed Generation of α,β-Unsaturated Acyl Imidazoliums: Synthesis of Dihydropyranones by their Reaction with Enolates
300 Citations2009Sarah J. Ryan, Lisa Candish +1 more
Catalytic generation of alpha,beta-unsaturated acyl imidazolium cations and enolates has been achieved, and their involvement in a Michael addition acylation sequence exploited, to provide a range of dihydropyranones.
PubMedDiscovering New Reactions with N-Heterocyclic Carbene Catalysis.
283 Citations2009Eric M. Phillips, Audrey Chan +1 more
The successful isolation of carbenes with less bulky substituents demonstrates that electronic factors may have greater impact on the stability of the carbene than steric ones.
Journal of the American Chemical SocietyOrganocatalytic Functionalization of Carboxylic Acids: Isothiourea-Catalyzed Asymmetric Intra- and Intermolecular Michael Addition−Lactonizations
274 Citations2011Dorine Belmessieri, Louis C. Morrill +3 more
Tetramisole promotes the catalytic asymmetric intramolecular Michael addition-lactonization of a variety of enone acids, giving carbo- and heterocyclic products with high diastereo- and enantiocontrol that are readily derivatized to afford functionalized indene and dihydrobenzofuran carboxylates.
Journal of the American Chemical SocietyEnantioselective Protonation of Catalytically Generated Chiral Enolates as an Approach to the Synthesis of α-Chloroesters
271 Citations2005Nathan T. Reynolds, Tomislav Rovis
Treatment of alpha,alpha-dichloroaldehydes with various phenols in the presence of chiral triazolium salt catalysts and excess base results in the synthesis of alpha-chloro aryl esters in good yield and enantioselectivity.
Journal of the American Chemical SocietyEnantioselective Synthesis of α,α-Disubstituted Cyclopentenes by an <i>N</i>-Heterocyclic Carbene-Catalyzed Desymmetrization of 1,3-Diketones
254 Citations2007Manabu Wadamoto, Eric M. Phillips +2 more
Organic & Biomolecular ChemistryN-Heterocyclic carbene catalysed β-lactam synthesis
243 Citations2008Nicolas Duguet, Craig D. Campbell +2 more
N-Heterocyclic carbenes promote the formal [2+2] cycloaddition of ketenes with N-tosyl imines to give the corresponding beta-lactams in good to excellent isolated yields; chiral NHCs give beta-Lactam in high e.e. after crystallisation.
Angewandte Chemie International Edition[4+2] Cycloaddition of Ketenes with <i>N</i>‐Benzoyldiazenes Catalyzed by N‐Heterocyclic Carbenes
239 Citations2008Xueliang Huang, Lin He +2 more
An unprecedented enantioselective [4+2] cycloaddition reaction of ketenes with N-benzoyldiazenes catalyzed by chiral NHCs to give 1,3,4-oxadiazin-6-ones is reported.
Angewandte Chemie International EditionOrganocatalytic Regio‐ and Stereoselective Inverse‐Electron‐Demand Aza‐Diels–Alder Reaction of α,β‐Unsaturated Aldehydes and <i>N</i>‐Tosyl‐1‐aza‐1,3‐butadienes
222 Citations2009Bo Han, Zhao‐Quan He +5 more
A highly enantioselective inverse-electron-demand aza-Diels–Alder reaction of N-sulfonyl 1-aza-1,3-butadienes and aliphatic aldehydes to form optically pure piperidines through enamine activation is presented.
Accounts of Chemical ResearchAdvances in the Catalytic, Asymmetric Synthesis of β-Lactams
219 Citations2004Stefan France, Anthony Weatherwax +2 more
The contribution to the catalytic, asymmetric synthesis of beta-lactams through a flexible [2 + 2] cycloaddition strategy is illustrated and the scope of the methodology is explored.
TetrahedronCatalytic, asymmetric reactions of ketenes and ketene enolates
212 Citations2009Daniel H. Paull, Anthony Weatherwax +1 more
Ketenes are versatile starting materials for a wide variety of compounds of interest and have been used as precursors for everything from industrially produced acetic acid to antibiotics and more, and through catalytic, asymmetric methodology, researchers have successfully utilized ketenes in a range of reaction manifolds.
Angewandte Chemie International EditionA Highly Enantioselective Intramolecular Michael Reaction Catalyzed by N‐Heterocyclic Carbenes
211 Citations2007Eric M. Phillips, Manabu Wadamoto +2 more
N-heterocyclic carbenes (NHCs) are highly selective catalysts for the intramolecular Michael reaction of substrates 1 to afford dicarbonyl compounds 2 after the addition of an exogenous nucleophile.
PubMedAsymmetric <i>N</i>-Heterocyclic Carbene (NHC) Catalyzed Acyl Anion Reactivity.
205 Citations2011Harit U. Vora, Tomislav Rovis
The present review will discuss the advent and development of NHCs in the generation of acyl anion equivalents and their use in synthesis.
Chemical ScienceThe effect of the N-mesityl group in NHC-catalyzed reactions
203 Citations2011Jessada Mahatthananchai, Jeffrey W. Bode
Angewandte Chemie International EditionOrganocatalytic Asymmetric Inverse‐Electron‐Demand Aza‐Diels–Alder Reaction of <i>N</i>‐Sulfonyl‐1‐aza‐1,3‐butadienes and Aldehydes
198 Citations2008Bo Han, Jun‐Long Li +3 more
An unprecedented asymmetric aza-Diels–Alder of N-sulfonyl-1aza-1,3-butadienes and aldehydes might be developed by employing a similar strategy and the enantioselectivity could be improved.
Chemistry LettersDevelopment of Chiral Bicyclic Triazolium Salt Organic Catalysts: The Importance of the <i>N</i>-Aryl Substituent
180 Citations2007Tomislav Rovis
Angewandte ChemieOrganocatalytic Asymmetric Inverse‐Electron‐Demand Aza‐Diels–Alder Reaction of <i>N</i>‐Sulfonyl‐1‐aza‐1,3‐butadienes and Aldehydes
171 Citations2008Bo Han, Jun‐Long Li +3 more
Proceedings of the National Academy of SciencesChiral N-heterocyclic carbene-catalyzed generation of ester enolate equivalents from α,β-unsaturated aldehydes for enantioselective Diels–Alder reactions
170 Citations2010Juthanat Kaeobamrung, Marisa C. Kozlowski +1 more
The enolate structure is investigated using computational methods and it is found that it prefers conformations perpendicular to the triazolium core.
Angewandte Chemie International EditionDihydropyridones: Catalytic Asymmetric Synthesis, N‐ to C‐Sulfonyl Transfer, and Derivatizations
163 Citations2012Carmen Simal, Tomáš Lébl +2 more
Journal of the American Chemical SocietyN-Heterocyclic Carbene Catalyzed Asymmetric Hydration: Direct Synthesis of α-Protio and α-Deuterio α-Chloro and α-Fluoro Carboxylic Acids
163 Citations2010Harit U. Vora, Tomislav Rovis
The developed reaction allows for installation of analpha-deuterium to give rise to enantioenriched alpha-deutero alpha-halo acids using D(2)O as the deuteron source.
Chemistry LettersDual Activation in N-Heterocyclic Carbene-organocatalysis
155 Citations2011Keiichi Hirano, Isabel Piel +1 more
The Journal of Organic ChemistryFormal Cycloaddition of Disubstituted Ketenes with 2-Oxoaldehydes Catalyzed by Chiral N-Heterocyclic Carbenes
149 Citations2008Lin He, Hui Lv +2 more
Chiral N-hetereocyclic carbenes were found to be efficient catalysts for the formal [2 + 2] cycloaddition reactions of alkyl(aryl)ketenes with 2-oxoaldehydes to afford beta-lactones with alpha-quaternary-beta-tertiary stereocenters in high yields with good diastereoselectivities and excellent enantioselectivity.
Organic LettersChiral NHC-Catalyzed Oxodiene Diels−Alder Reactions with α-Chloroaldehyde Bisulfite Salts
138 Citations2008Ming He, Brendan J. Beahm +1 more
This new protocol makes possible enantioselective additions from commercially available chloroacetaldehyde sodium bisulfite and demonstrates that this unique class of catalysts readily tolerates aqueous conditions.
Organic LettersEnantioselective Diels–Alder Reactions of Enals and Alkylidene Diketones Catalyzed by N-Heterocyclic Carbenes
132 Citations2011Xinqiang Fang, Xingkuan Chen +1 more
An electron-withdrawing group was introduced to the α-position of chalcones, and the resulting alkylidene diketones showed new reactivities with enals under the catalysis of N-heterocyclic carbenes (NHCs).
Angewandte Chemie International EditionN‐Heterocyclic Carbene Catalysis: Enantioselective Formal [2+2] Cycloaddition of Ketenes and <i>N</i>‐Sulfinylanilines
126 Citations2011Tengyue Jian, Lin He +2 more
It is envisioned that the 3-oxo-b-sultams could be easily synthesized by oxidation of the corresponding 1,2-thiazetidin3-one 1-oxides, which could be accessed from the [2+2] cycloaddition of ketenes with N-sulfinylamines.
Organic LettersThe Total Synthesis of (−)-7-Deoxyloganin via <i>N</i>-Heterocyclic Carbene Catalyzed Rearrangement of α,β-Unsaturated Enol Esters
123 Citations2010Lisa Candish, David W. Lupton
The diastereoselective N-heterocyclic carbene (NHC) catalyzed rearrangement of α,β-unsaturated enol ester has been used to assemble dihydropyranone (S)-3b, a material embodying the bicyclic core of the iridoid family of natural products.
Chemical CommunicationsEnantioselective [4+2] cycloaddition of ketenes and 1-azadienes catalyzed by N-heterocyclic carbenes
120 Citations2010Tengyue Jian, Pan‐Lin Shao +1 more
Optically active highly functionalized 3,4-dihydropyridin-2-ones were synthesized by N-heterocyclic carbene-catalyzed [4+2] enantioselective cycloaddition of ketenes and 1-azadienes.
Organic Letters<i>N</i>-Heterocyclic Carbene Catalyzed Ring Expansion of Formylcyclopropanes: Synthesis of 3,4-Dihydro-α-pyrone Derivatives
116 Citations2009Gongqiang Li, Li‐Xin Dai +1 more
N-Heterocyclic carbene catalyzed ring expansion of readily accessible 2-acyl-1-formylcyclopropanes led to 3,4-dihydro-alpha-pyrones in good to excellent yields.
Journal of the American Chemical Society<i>N</i>-Heterocyclic Carbene-Catalyzed Enantioselective Mannich Reactions with α-Aryloxyacetaldehydes
114 Citations2009Yasufumi Kawanaka, Eric M. Phillips +1 more
N-Heterocyclic carbenes catalyze a new Mannich-type reaction to form beta-amino acid derivatives in high yield and enantioselectivity in a new carbene catalysis concept and the activated ester products formed in situ are manipulated to form a variety of useful compounds.
Journal of the American Chemical SocietyCatalytic, Enantioselective [4 + 2]-Cycloadditions of Ketene Enolates and <i>o</i>-Quinones: Efficient Entry to Chiral, α-Oxygenated Carboxylic Acid Derivatives
113 Citations2006Tefsit Bekele, Meha H. Shah +4 more
Chemical Communicationsα-Aroyloxyaldehydes: scope and limitations as alternatives to α-haloaldehydes for NHC-catalysed redox transformations
111 Citations2010Kenneth B. Ling, Andrew D. Smith
α-Aroyloxyaldehydes are readily prepared bench stable synthetic intermediates that act as α-haloaldehyde surrogates for NHC-promoted redox esterifications and in [4+2] cycloadditions.
Organic LettersEfficient N-Heterocyclic Carbene-Catalyzed <i>O</i>- to C-Acyl Transfer
111 Citations2006Jennifer E. Thomson, Kathryn Rix +1 more
An N-heterocyclic carbene promotes the rearrangement of alpha-amino acid derived O-acyl carbonates to their corresponding C-acylated isomers, generating a C-C bond and a quaternary stereocenter with high efficiency, under mild reaction conditions and with low catalyst loadings.
Dalton TransactionsFused polycyclic nucleophilic carbenes – synthesis, structure, and function
107 Citations2009Anthony J. Arduengo, Luigi I. Iconaru
Fused polycyclic carbenes is a broad chemical class that has opened many new opportunities for improvements in chemical transformations and invention of new processes from both a structural and reactivity perspective.
Organic Letters<i>N</i>-Heterocyclic Carbene Catalyzed Ring Expansion of 4-Formyl-β-lactams: Synthesis of Succinimide Derivatives
107 Citations2007Gongqiang Li, Yi Li +2 more
N-heterocyclic carbene has been employed as an efficient catalyst for ring expansion of 4-formyl-beta-lactams, allowing the facile synthesis of succinimide derivatives.
Current Organic ChemistryN-Heterocyclic Carbene-Catalyzed Redox Reactions of &#945;-Functionalized Aldehydes
103 Citations2011Zi‐Qiang Rong, Wei Zhang +2 more
Organic LettersNHC-Catalyzed Ring Expansion of Oxacycloalkane-2-carboxaldehydes: A Versatile Synthesis of Lactones
101 Citations2009Li Wang, Karen Thai +1 more
Imidazolinium-derived carbenes catalyze the ring-expansion lactonization of oxacycloalkane-2-carboxaldehydes and a variety of functionalized five-, six-, and seven-membered lactones can be formed efficiently under mild reaction conditions.
Organic LettersSynthesis of an <i>N</i>-Mesityl Substituted Chiral Imidazolium Salt for NHC-Catalyzed Reactions
96 Citations2008Justin R. Struble, Juthanat Kaeobamrung +1 more
These studies confirm striking differences in reactivity and mechanism between the two classes of imidazolium precursors across a number of NHC-catalyzed processes.
Organic LettersFormal Diels–Alder Reactions of Chalcones and Formylcyclopropanes Catalyzed by Chiral N-Heterocyclic Carbenes
91 Citations2011Hui Lv, Junming Mo +2 more
The challenging N-heterocyclic carbene-bounded enolate intermediates from formylcyclopropanes were captured for new C-C bond forming reactions and could be easily transformed to optically pure multisubstituted cyclohexane derivatives.
Organic LettersNHC-Catalyzed Reactions of Aryloxyacetaldehydes: A Domino Elimination/Conjugate Addition/Acylation Process for the Synthesis of Substituted Coumarins
85 Citations2008Eric M. Phillips, Manabu Wadamoto +3 more
N-heterocyclic carbenes (NHCs) catalyze a domino Michael addition/acylation reaction to form 3,4-dihydrocoumarins.
Advanced Synthesis & CatalysisN‐Heterocyclic Carbene‐Mediated Enantioselective Addition of Phenols to Unsymmetrical Alkylarylketenes
81 Citations2009Carmen Concellón, Nicolas Duguet +1 more
Organic Letters<i>N</i>-Heterocyclic Carbene-Catalyzed Internal Redox Reaction of Alkynals: An Efficient Synthesis of Allenoates
72 Citations2012Yu‐Ming Zhao, Yik Tam +3 more
An efficient N-heterocyclic carbene (NHC)-catalyzed internal redox reaction of alkynals that bear a γ leaving group has been developed and provides a new access to a range of allenoates in good yields.
Chemical CommunicationsInvestigating organocatalytic reactions: mass spectrometric studies of a conjugate umpolung reaction
68 Citations2006Wolfgang Schräder, Peni Purwa Handayani +2 more
An organocatalyzed conjugate umpolung reaction has been studied in detail using electrospray mass spectrometry, which allows to support the catalytic cycle by intercepting intermediates.
Organic LettersOrganocatalytic Enantioselective Synthesis of Nitrogen-Substituted Dihydropyran-2-ones, a Key Synthetic Intermediate of 1β-Methylcarbapenems
65 Citations2009Shöji Kobayashi, Tatsuhiro Kinoshita +3 more
Organocatalytic enantioselective cycloadditions providing nitrogen-substituted dihydropyran-2-ones were developed in two catalytic systems and the (3R,4R)-product was a versatile intermediate in the synthesis of 1beta-methylcarbapenem antibiotics.
The Journal of Organic ChemistryN-Heterocyclic Carbene-Catalyzed Domino Ring-Opening/Redox Amidation/Cyclization Reactions of Formylcyclopropane 1,1-Diesters: Direct Construction of a 6−5−6 Tricyclic Hydropyrido[1,2-<i>a</i>]indole Skeleton
60 Citations2009Ding Du, Linxia Li +1 more
This methodology provides an efficient and direct construction of a 6-5-6 tricyclic hydropyrido[1,2-a]indole skeleton, which can be potentially applied for the synthesis of several types of polycyclic indole alkaloids.
Journal of the American Chemical SocietyA Surprising Mechanistic “Switch” in Lewis Acid Activation: A Bifunctional, Asymmetric Approach to α-Hydroxy Acid Derivatives
60 Citations2008Ciby J. Abraham, Daniel H. Paull +4 more
A detailed synthetic and mechanistic study of an unusual bifunctional, sequential hetero-Diels-Alder/ring-opening reaction in which chiral, metal complexed ketene enolates react with o-quinones to afford highly enantioenriched, alpha-hydroxylated carbonyl derivatives in excellent yield.
Organic LettersHighly Enantioselective Cyclizations of Conjugated Trienes with Low Catalyst Loadings: A Robust Chiral <i>N</i>-Heterocyclic Carbene Enabled by Acetic Acid Cocatalyst
52 Citations2012Guansai Liu, Phillip D. Wilkerson +2 more
It is discovered that acetic acid not only could coexist with NHCs but also could greatly stabilize the active catalyst, which enables a long-lived catalyst with high reactivity and selectivity.
Chemical CommunicationsDirect organocatalytic synthesis of enantiopure succinimides from β-lactam aldehydes through ring expansion promoted by azolium salt precatalysts
49 Citations2007Benito Alcaide, Pedro Almendros +2 more
A single-step catalytic ring expansion approach from 4-oxoazetidine-2-carbaldehydes to enantiopure succinimides has been achieved by the use of a base and a thiazolium salt precatalyst.
European Journal of Organic ChemistryNHC‐Mediated Chlorination of Unsymmetrical Ketenes: Catalysis and Asymmetry
47 Citations2010James J. Douglas, Kenneth B. Ling +4 more
NHCs promote the efficient chlorination of unsymmetrical disubstituted ketenes with a range of chlorinating agents; chiral NHCs display promising levels of asymmetric induction in the chlorination process with up to 61 % observed using 2,3,4,5,6,6-hexachlorocyclohexa-2,4-dienone.
CHIMIA International Journal for ChemistryCatalytic, Asymmetric Inverse Electron Demand Hetero Diels-Alder Reactions of o-Benzoquinone Derivatives and Ketene Enolates
27 Citations2007Daniel H. Paull, Jamison Wolfer +3 more
…