Copper-catalyzed ring-opening of heterobicyclic alkenes with Grignard reagents:: Remarkably high anti-stereocontrol

Unlike most of the reported protocols for the ring-opening reaction of heterobicyclic alkenes with carbon nucleophiles which typically occur with syn selectivity, the alkylative ring-opening reaction of [2.2.1]oxa- and azabicyclic alkenes with Grignard reagents in the presence of a catalytic amount of copper(l) takes place with very high or complete anti-stereocontrol under smooth reaction conditions. This new procedure proved to be wide in scope with respect to both the Grignard reagent and the bicyclic alkene. Especially noteworthy is the facile ring-opening reaction of low reactive substrates such as nonaromatic oxabicyclic alkenes and aza-benzonorbornadienes under this catalyst system.