Stereoselective synthesis of (Z/E)-1,2-dibromoalkenes from terminal alkynes

A Ag–CH 3 SO 3 H co-catalyzed direct Z -selective synthesis of 1,2- cis -dibromoalkenes from alkynes has been developed. Meanwhile, the PPh 3 -promoted E -selective synthesis of 1,2- trans -dibromoalkenes from alkynes is also disclosed.