(Z)-Selective Hydroboration of Terminal Alkynes Catalyzed by a PSP-Pincer Rhodium Complex.

A highly (Z)-selective hydroboration of terminal alkynes was achieved using a thioxanthene-based PSP-pincer rhodium catalyst. This hydroboration exhibited good chemoselectivity toward alkynes over carbonyl compounds such as ketones and aldehydes. The mechanistic studies indicated the involvement of rhodium-vinylidene intermediates, and the high (Z)-selectivity could be attributed to the rigid and electron-rich nature of the PSP-rhodium catalyst.