Asymmetric O-H insertion reaction of carbenoids catalyzed by chiral bicyclo bisoxazoline copper(I) and (II) complexes

Chiral copper(I) and (II)-bicyclobisoxazoline complexes were found to catalyze the insertion of alpha-diazocarbonylcompounds into O-H bonds of alcohols. The insertion reactions of various alpha-diazopropionates proceeded with moderate yields (40-90%) and high enantioselectivities (up to 92% and 94% with copper(I) and copper(II)-catalysts, respectively). A predominant effect on the enantiocontrol of the reaction was observed when copper(I) and (II)-catalysts were associated with NaBARF and molecular sieves (4 angstrom). (C) 2016 Elsevier Ltd. All rights reserved.