B(C6F5)3-catalyzed bisthiolation of terminal alkynes: regioselective metal-free synthesis of 2-methyl-1,3-dithiolanes

We report a metal-free protocol for the bisthiolation of terminal alkynes with 1,2-ethanedithiol catalyzed by commercially available tris(pentafluorophenyl)borane B(C 6 F 5 ) 3 . This readily implementable, scalable reaction operates under mild conditions, showing broad substrate compatibility. Developed method demonstrates excellent yields and Markovnikov regioselectivity across a range of substrates. A plausible reaction mechanism proceeding via alkyne-catalyst zwitterionic intermediates was also proposed. Efficient derivatization of model dithiolane product highlighted its suitability for subsequent functionalization.