Fig. 1: Different reaction models induced by chiral BINOL aldehyde catalysts.

a Reaction model I induced by 3-formyl BINOL aldehyde I. b Reaction model II induced by 2-formyl BINOL aldehyde II.
a Reaction model I induced by 3-formyl BINOL aldehyde I. b Reaction model II induced by 2-formyl BINOL aldehyde II.