Highly Enantioselective Trapping of Carboxylic Oxonium Ylides with Imines for Direct Assembly of Enantioenriched γ-Butenolides

Enantioenrichedγ-butenolides are valuable structural cores in many pharmaceuticals and natural products,but their direct and catalytically asymmetric assembly remains rare.Here,we report an efficient,atom-economic synthetic strategy for enantioenrichedγ-butenolides via a unique enantioselective reaction of cyclopropene carboxylic acids with imines under the synergistic catalysis of Rh2(esp)2/chiral Brønsted acid system.The reaction involved trapping of carboxylic oxonium ylides,generated from cyclopropene carboxylic acids,which presented as the first asymmetric trapping reactive intermediate in the process.

A sustainable synthesis of 3,3-disubstituted oxindoles via CuBr-catalysed capture of carboxylic oxonium ylides with isatylidene malononitrile

We herein reported a sustainable synthesis of 3,3-disubstituted oxindoles via a Michael-type reaction based on the CuBr-catalysed capture of carboxylic oxonium ylides with isatylidene malononitrile.The reaction is characterized by a high atom economy and low economic constraints.The catalyst CuBr could be conveniently recyclized.The products of the reaction were found to be inhibitory against Na ion channels.We expect the reaction to shed the light on synthesis of biologically interesting molecules directed by principles of green chemistry.