Asymmetric Cyclization of 2′-Hydroxychalcones to Flavanones: Catalysis by Chiral Brønsted Acids and Bases
作者:Claudia Dittmer、Gerhard Raabe、Lukas Hintermann
DOI:10.1002/ejoc.200700682
日期:2007.12
the realization of an asymmetric flavanone synthesis by means of camphorsulfonic acid as chiral Bronsted acid catalysts were reinvestigated using accurate HPLC methods for quantification of enantiomer ratios. The previous claims of asymmetric induction were thus shown to be untenable. On the other hand, cinchonaalkaloids serve as chiral Bronsted base mediators for the asymmetric cyclization of either