Regiospecific and stereoselective synthesis of (E)- and (Z)-2-phosphino-1-alkenyl boronates via Cu-catalyzed hydroboration of alkynylphosphines

We have developed the regiospecific and stereoselective synthesis of (E)- and (Z)-2-phosphino-1-alkenyl boronates via Cu-catalyzed hydroboration of alkynylphosphines. A remarkable ligand-controlled stereoselectivity in the transformation is presented. The study on the coordination chemistry of the new phosphine/borane compounds with gold suggests the presence of very weak Au → B interaction in the gold complex 4 ligated by (E)-2-phosphino-1-alkenyl boronate 2a.