Alumina was found to activate Cu(I) catalysts in hydroboration of alkynes. This allowed
to develop a simple and efficient protocol for hydroboration of alkynes with B2Pin2 using inexpensive CuCl/PPh3 catalytic system. The approach does not require moisture-sensitive activators and
stepwise preparation of ‘activated’ Cu complex. The developed conditions were applied
to the preparation of β-styrylboronates from terminal and internal alkynes with excellent
regio- and stereoselectivity. The procedure can also be extended to other terminal
alkynes by the appropriate choice of ligand.
Key words
alumina - copper - hydroboration - alkynes - vinylboronic esters - stereoselective
synthesis