N-heterocyclic carbene catalyzed annulation of enals to aurone analogs: synthesis of cyclopentene-fused spirobenzofuran-3-ones.

A nucleophilic heterocyclic carbene mediated homoenolate annulation of enals to aurone analogs leading to the efficient synthesis of cyclopentene-fused spirobenzofuran-3-ones is reported.

A novel intramolecular homoenolate annulation leading to the formation of cyclopentene-fused macrocycles.

A nucleophilic heterocyclic carbene-mediated intramolecular homoenolate reaction strategy for the efficient synthesis of cyclopentene-fused macrocycles is reported.

N-Heterocyclic carbene catalyzed reaction of cinnamils leading to the formation of 2,3,8-triaryl vinyl fulvenes: an uncommon transformation.

An unexpected transformation of 1,6-diarylhexa-1,5-diene-3,4-diones (cinnamils) to 2,3,8-triaryl vinyl fulvenes via N-Heterocyclic Carbene (NHC) catalysis is reported. Mechanistic as well as synthetic novelty is the hallmark of this reaction.

A cascade reaction actuated by nucleophilic heterocyclic carbene catalyzed intramolecular addition of enals via homoenolate to α,ß-unsaturated esters: efficient synthesis of coumarin derivatives.

A nucleophilic heterocyclic carbene mediated intramolecular homoenolate reaction strategy for the efficient synthesis of 4-alkyl substituted coumarins is described.

Employing homoenolates generated by NHC catalysis in carbon-carbon bond-forming reactions: state of the art.

Homoenolate is a reactive intermediate that possesses an anionic or nucleophilic carbon ß to a carbonyl group or its synthetic equivalent. The recent discovery that homoenolates can be generated from α,ß-unsaturated aldehydes via N-Heterocyclic Carbene (NHC) catalysis has led to the development of a number of new reactions. A majority of such reactions include the use of carbon-based electrophiles, such as aldehydes, imines, enones, dienones etc. resulting in the formation of a variety of annulated as well as acyclic products. The easy availability of chiral NHCs has allowed the development of very efficient enantioselective variants of these reactions also. The tolerance showed by NHCs towards magnesium and titanium based Lewis acids has been exploited in the invention of cooperative catalytic processes. 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.

A novel NHC-catalyzed transformation of 2H-chromene-3-carboxaldehydes to 3-methyl-2H-chromen-2-ones.

An unexpected transformation of 2H-chromene-3-carboxaldehydes to coumarin derivatives, mediated by NHC, is reported.

NHC catalyzed transformation of aromatic aldehydes to acids by carbon dioxide: an unexpected reaction.

A facile NHC-mediated reaction of aromatic aldehydes with carbon dioxide leading to carboxylic acids is described. The present protocol is mechanistically important, and it can serve as a tool for the sequestration of carbon dioxide.

A novel pseudo four component reaction involving homoenolate for the synthesis of gamma-aminobutyric acid (GABA) derivatives.

Homoenolate generated from alpha,beta-unsaturated aldehydes by NHC catalysis underwent facile addition to conjugated sulfonimines, generated in situ, and subsequent methanolysis to afford protected GABA derivatives stereoselectively and in high yields, thus constituting a novel pseudo four component reaction.

Novel nucleophilic heterocyclic carbene mediated stereoselective conjugate addition of enals to nitrostyrenes via homoenolate.

A stereoselective Michael addition of homoenolate, generated from enals by nucleophilic heterocyclic carbene (NHC) catalysis, to beta-nitrostyrenes is reported for the first time. The products of this reaction obtained in good yields are of potential value in the synthesis of a variety of acyclic and heterocyclic compounds.