Highly regio- and stereoselective synthesis of alkenylboronic esters by copper-catalyzed boron additions to disubstituted alkynes

The copper-catalyzed addition of bis(pinacolato)diboron to internal alkynes in the presence of methanol generates alkenylboron compounds with high levels of regio- and stereoselectivities. The catalytic efficiency is increased by using monodentate phosphine ligands, especially P(p-tolyl)(3) and a range of internal alkynes was borylated in good yields.