Hydrothiolation of Unactivated Alkynes Catalyzed by Indium(III) Bromide

Indium(III) bromide is found to catalyze efficiently the hydrothiolation of unactivated alkynes with various thiols under mild conditions to produce the corresponding dithioacetals in excellent yields. However, addition of aromatic thiols on aromatic alkynes gave the β-vinyl sulfides in high yields. This new procedure offers significant advantages such as high conversions, short reaction times, and simplicity in operation.