Progress in Catalytic Asymmetric Protonation : Progress in Catalytic Asymmetric Protonation

Treatment of alpha,alpha-dichloroaldehydes with various phenols in the presence of chiral triazolium salt catalysts and excess base results in the synthesis of alpha-chloro aryl esters in good yield and enantioselectivity. The reaction is tolerant of various functionality on the aldehyde as well as several electronically diverse phenols. The product chloroesters were further transformed into chloroacid, chlorohydrin, and azidoesters with nearly complete retention of enantioselectivity.