Copper-catalyzed decarboxylative hydroboration of phenylpropiolic acids under ligand-free or both ligand- and base-free conditions

An efficient copper-catalyzed decarboxylative hydroboration of phenylpropiolic acids with bis(pinacolato)diboron was developed, affording beta-vinylboronates as the only products in high yields. Extra hydrogen sources such as methanol are not needed in this catalytic system. This reaction could be performed successfully under ligand- and base-free conditions. It demonstrated that phenylpropiolic acids can be employed as alkyne synthons in the hydroboration reaction and exhibited good reactivity and higher selectivity than terminal alkynes. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.