The synthesis of allenes by Cu(I)-catalyzed regio- and stereoselective reduction of propargylic carbonates with hydrosilanes.

Cu(I)-catalyzed anti-S(N)2'-type reduction of internal propargylic carbonates with hydrosilanes affords various di- and trisubstituted allenes with high regioselectivities; the reactions are compatible with functional groups and work efficiently for the synthesis of optically-active allenes.