Tandem intramolecular oxa-Michael addition/decarboxylation reaction catalyzed by bifunctional cinchona alkaloids: facile synthesis of chiral flavanone derivatives

Bifunctional cinchona alkaloids were used to catalyze a tandem intramolecular oxa-Michael addition/decarboxylation reaction of alkylidene β-ketoesters 1, providing a series of flavanone derivatives with up to 97% yield and 93% ee.