title: N-heterocyclic carbene-catalyzed generation of homoenolates: gamma-butyrolactones by direct annulations of enals and aldehydes.
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.
authors.affiliation: Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106-9510, USA.
authors.forename: Stephanie S
authors.initials: SS
authors.lastname: Sohn
authors.forename: Evelyn L
authors.initials: EL
authors.lastname: Rosen
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Bode