Catalytic One-Pot Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones.

An efficient one-pot synthesis of trisubstituted allenes from readily available terminal alkynes and ketones is realized. A wide range of trisubstituted allenes may be synthesized efficiently via this method. Preliminary mechanistic studies revealed that CuI and Ti(OEt)4 are in charge of the formation of propargylic amine, while ZnBr2 is responsible for the transformation from propargylic amine to allene.