Abstract The asymmetric cyclization of 2′-hydroxychalcones to flavanones is a basic, enzyme-catalyzed step in the biosynthesis of flavonoid natural products, but poses a long- standing problem for asymmetric catalysis with small molecule catalysts. Earlier claims concerning the realization of an asymmetric flavanone synthesis by means of camphorsulfonic acid as chiral Brønsted acid catalysts were reinvestigated using accurate ...
