Modified Chiral Triazolium Salts for Enantioselective Benzoin Cyclization of Enolizable Keto-Aldehydes: Synthesis of (+)-Sappanone B
摘要:
Asymmetric synthesis of (+)-sappanone B (1), a natural product with a 3-hydroxy chromanone structure, was achieved via enantioselective benzoin cyclization by using a modified Rovis catalyst and triethylamine. This catalyst enabled the successful benzoin cyclization of readily enolizable keto-aldehydes.
Rh-Catalyzed Carbonyl Hydroacylation: An Enantioselective Approach to Lactones
作者:Zengming Shen、Hasan A. Khan、Vy M. Dong
DOI:10.1021/ja7109025
日期:2008.3.1
This communication describes the design and execution of a novel approach to forming chiral lactones via C−H bond activation. The strategy features an unprecedented enantioselective Rh-catalyzed hydroacylation of carbon−oxygen double bonds. Representative keto-aldehydes (derived from salicylaldehyde) undergo cyclization with complete regioselectivity to afford seven-membered lactones in great enantiomeric