Asymmetric Induction in the Arenethiolatocopper(I)-Catalyzed Substitution Reaction of Grignard Reagents with Allylic Substrates

The influence of some experimental parameters on the regio- and enantioselectivity in the γ-selective substitution reaction of Grignard reagents RMgX with acyclic allylic acetates catalyzed by the arenethiolatocopper(I) complex (S)-1 was studied. When more bulky arenethiolatocopper(I) complexes than (S)-1 were employed in a reaction of allylic acetate 3 with n-BuMgI, the enantioselectivities observed for the γ-product were lower. With an arenethiolatocopper(I) catalyst prepared in situ, several Grignard reagents were studied in a substitution reaction with acetate 2. Compared to n-BuMgI, more bulky Grignard reagents gave no improvement of the enantioselectivity in the formation of the γ-product.