Chemoselective Synthesis of 1,1-Disubstituted Vinyl Triflates from Terminal Alkynes Using TfOH in the Presence of TMSN3.

1,1-Disubstituted vinyl triflates are synthesized by direct hydrotriflation of terminal alkynes employing a combination of TfOH and TMSN3 in DCM at room temperature. Interestingly, under these conditions, only terminal alkynes were selectively converted to the corresponding vinyl triflates, while internal alkynes were not reacted. A broad range of substrates were successfully converted to the corresponding 1,1-disubstituted vinyl triflates in good to excellent yields even those with internal alkyne moieties present in the molecules.