Catalyst-Free and Solvent-Free Hydroboration of Alkynes and Alkenes with Catecholborane

A catalyst-free and solvent hydroboration of alkynes and alkenes with catecholborane was reported. Various alkynes and alkenes including aromatic and aliphatic groups were smoothly converted into the corresponding anti-Markovnikov alkenyl and alkyl boronate esters in high yields and high regio/stereoselectivity at room temperature and 50., respectively. The gram-scale hydroboration and further versatile conversions demonstrated great potential in the practical application. A plausible reaction mechanism was proposed based on the corresponding density function theory (DFT) calculations.