CuBr2-catalyzed enantioselective routes to highly functionalized and naturally occurring allenes

Here we show the CuBr2-catalyzed approach for highly enantioselective synthesis (90-98% ee) of allenes bearing a very broad array of unmasked synthetically attractive functionalities from aldehydes and terminal alkynyl bearing reactive functionalities with the absolute configuration controlled by applying readily available (R)- or ( S)-alpha,alpha-diphenylprolinol. Following this protocol, the highly enantioselective synthesis of some naturally occurring allenes loaded with reactive functionalities becomes simple: a terminal alkyne plus an aldehyde. In comparison, they were reported to be synthesized either from similar level generic chemicals with much more steps or in lower ees.