Organocatalytic trans Phosphinoboration of Internal Alkynes.

: We report the first trans phosphinoboration of internal alkynes. Employing an organophosphine catalyst, alkynoate esters and the phosphinoboronate Ph 2 P-Bpin are efficiently converted to the corresponding trans α-phosphino-β-boryl acrylate products in moderate to good yield with high regio- and Z -selectivity. This reaction operates under mild conditions and demonstrates good atom economy, requiring only a modest excess of the phosphinoboronate. X-ray crystallography experiments allowed structural assignment of the unprecedented and densely functionalized ( Z )-α-phosphino-β-boryl acrylate products.