An organocatalyzed method for synthesizing
chiral γ,γ-disubstituted
γ-butenolides via direct vinylogous aldol reactions of γ-substituted
β,γ-butenolides with aldehydes is reported. This reaction
is catalyzed by a squaramide–sulfonamide organocatalyst to
afford a range of anti-aldol adducts possessing vicinal
quaternary and tertiary stereocenters with high to excellent enantioselectivities
(reaching 95% ee). This is the first report of a successful stereoselective
direct vinylogous aldol reaction of aldehydes with γ-substituted
β,γ-butenolides.
Asymmetric conjugate additions of phosphonates to trans-crotonophenone and chalcone derivatives using a diaminomethylenemalononitrile organocatalyst resulted in the generation of the corresponding chiral γ-ketophosphonates in high yields with excellent enantioselectivities (up to 95% ee). This report is the first successful example of asymmetric 1,4-additions of phosphonate to α,β-unsaturated ketones using an organocatalyst.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.