N-heterocyclic carbene-catalyzed generation of homoenolates: gamma-butyrolactones by direct annulations of enals and aldehydes

Stephanie S Sohn; Evelyn L Rosen; Jeffrey W Bode

doi:10.1021/ja044714b

N-heterocyclic carbene-catalyzed generation of homoenolates: gamma-butyrolactones by direct annulations of enals and aldehydes

J Am Chem Soc. 2004 Nov 10;126(44):14370-1. doi: 10.1021/ja044714b.

Authors

Stephanie S Sohn¹, Evelyn L Rosen, Jeffrey W Bode

Affiliation

¹ Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106-9510, USA.

PMID: 15521753
DOI: 10.1021/ja044714b

Abstract

N-Heterocyclic carbenes, prepared in situ from diarylimidazolium salts, serve as highly effective catalysts for the generation of reactive homoenolates from alpha,beta-unsaturated aldehydes. The catalyst-bound homoenolate reacts with electrophilic aldehydes leading, via the key intermediacy of an activated carboxylate, to gamma-butyrolactones in good yields and stereoselectivities. Importantly, this process demonstrates an unprecedented reaction mode for the generation of nucleophilic carbanions with a multifunctional organocatalyst under exceptionally mild and convenient reaction conditions.