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 enantiosele ctivity in the gamma-selective substitution reaction of Grignard reagents R MgX with acyclic allylic acetates catalyzed by the arenethiolatocopper(I) c omplex (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, t he enantioselectivities observed for the gamma-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-BuMg I, more bulky Grignard reagents gave no improvement of the enantioselectivi ty in the formation of the gamma-product. (C) 2000 Elsevier Science Ltd. Al l rights reserved.