Convenient procedures for the asymmetric reductions utilizing α,α-diphenyl- pyrrolidinemethanol and borane complexes generated using the I2/NaBH4 system

Abstract

Syntheses of oxazaborolidine in situ in benzene using α,α-diphenylpyrrolidinemethanol and diborane, generated from the iodine-sodium borohydride system are described. The oxazaboro- lidine (10 mole%), generated by the reaction of α,α-diphenylpyrrolidinemethanol and diborane in benzene followed by heating with N,N-diethylaniline, in combination with boranetetrahydrofuran complex reduces acetophenone to 1-phenylethanol in 94.7% ee. © 1994.