Highly Stereo- and Regioselective Hydrostannylation of Internal Alkynes Promoted by Simple Boric Acid in Air

Facile hydrostannylation of alkynes in air: The ability to prepare vinylstannanes of high regio- and sterochemical fidelity in a safe manner employing a simple operational set up, especially on a large scale, has remained elusive. This study has shown that all of the autoxidation products of Et(3) B and boronic acids are capable of promoting hydrostannylation. Most importantly, simple boric acid itself can also promote the hydrostannylation of highly functionalized internal alkynes with complete selectivity under very mild conditions (RT to 80 °C) in air.