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.