Synthesis of novel carbohydrate-based valine-derived formamide organocatalysts by CuAAC click chemistry and their application in asymmetric reduction of imines with trichlorosilane

Abstract

Novel organocatalysts combining carbohydrate and N-formyl-l-valine derivatives were prepared by CuII-catalyzed diazo transfer and CuI-catalyzed azide–alkyne 1,3-dipolar cycloaddition CuAAC click chemistry. It was found that the carbohydrate-based valine-derived formamide organocatalyst had high catalytic activity for the asymmetric reduction of imines with trichlorosilane. The reduction can proceed at room temperature in toluene in high yield (up to 98%) and with excellent enantioselectivity (up to 94%). ‘CuAAC’ click chemistry is a bridge to link N-formyl-l-valine derived organocatalysts with carbohydrates.