Rational electronic tuning of CBS catalyst for highly enantioselective boranereduction of trifluoroacetophenone

Abstract

α,α,α-Trifluoroacetophenone (2), which is susceptible to noncatalytic reduction by BH₃, could be reduced to chiral alcohol up to 90% ee by using electronically tuned-CBS catalyst (1) with BH₃. The enantioselectivities highly correlated with the differential orbital energies between 1–BH₃ adduct and 2, which were calculated by DFT method.