Regioselective and Stereospecific Hydrostannation on Terminal Alkynes.

We report a ruthenium-catalyzed regioselective and stereospecific hydrostannation of terminal alkynes in a switchable solvent system under ambient conditions. This method exhibits excellent selectivity and functional group tolerance, enabling controlled Markovnikov and anti-Markovnikov addition of tributyl tin hydride to the C(sp)-C(sp) bond. The stereospecific formation of (E)-β-vinylstannane from (Z)-β-vinylstannane by isomerization at high temperatures was verified through a detailed NMR study. We also demonstrated the utility of this method by synthesizing an organotin-containing boronic ester that can be used for sequential cross-coupling reactions as a nucleophilic partner.