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.
Ruthenium-NHC-Catalyzed Asymmetric Hydrogenation of Flavones and Chromones: General Access to Enantiomerically Enriched Flavanones, Flavanols, Chromanones, and Chromanols
作者:Dongbing Zhao、Bernhard Beiring、Frank Glorius
DOI:10.1002/anie.201302573
日期:2013.8.5
Two to four! Readily available flavones and chromones were efficiently converted into four valuable chiral classes of O‐heterocycles—flavanones, chromanones, flavanols, and chromanols—by means of an enantioselective Ru/NHC‐catalyzed hydrogenation process (see scheme; NHC=N‐heterocyclic carbene, PCC=pyridinium chlorochromate).
Tandem intramolecular oxa-Michael addition/decarboxylation reaction catalyzed by bifunctional cinchona alkaloids: facile synthesis of chiral flavanone derivatives
作者:Hai-Feng Wang、Hua Xiao、Xiao-Wei Wang、Gang Zhao
DOI:10.1016/j.tet.2011.05.088
日期:2011.7
Bifunctionalcinchonaalkaloids 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.