The regiochemistry of the stannylcupration of allenes: synthesis of allylstannanes using the lower order cuprate (Bu3Sn)CuCNLi

The lower order cuprate (Bu3Sn)CuCNLi, prepared by mixing 1 equiv of tributylstannyllithium and 1 equiv of copper(I) cyanide, reacts with allenes showing a regiochemistry opposite to that previously reported for higher order stannylcuprates. Capture of the intermediate allylstannane–vinylcuprate species with different electrophiles allows the selective formation of allylstannanes with different substitution pattern. Reaction with acetylenes was also checked.