Lewis acid-catalyzed hydrometalation and carbometalation of unactivated alkynes

Hydrosilylation, hydrostannation, carbosilylation, and carbostannation of unactivated alkynes with organosilanes, or organostannanes proceed effectively in the presence of catalytic amounts of Lewis acids to produce the corresponding vinylsilyl or vinylstannyl compounds in a highly regio- and stereoselective way. Although it is well known that transition metal catalyzed hydrometalations and carbometalations, in general, proceed in a cis-manner, the Lewis acid-catalyzed reactions proceed in a trans-manner exclusively. The coordination of a triple bond to Lewis acids is proposed as a key step for the Lewis acid catalyzed reactions.