Catalytic Enantioselective Synthesis of Flavanones and Chromanones
摘要:
The enantioselective synthesis of flavanones and chromanones is described. Bifunctional thiourea catalysts promote an asymmetric oxo-conjugate addition to a beta-ketoester alkylidene in high yields with excellent enantioselectivity (80-94% ee) for aryl and alkyl substrates. Decarboxylation of the beta-ketoester proceeds smoothly in a one-pot procedure to afford the enantioenriched flavanones and chromanones.
Asymmetric Intramolecular Oxa-Michael Addition of Activated α,β-Unsaturated Ketones Catalyzed by a Chiral<i>N</i>,<i>N</i>′-Dioxide Nickel(II) Complex: Highly Enantioselective Synthesis of Flavanones