A metal-free regioselective hydrobromination of alkynes has been developed to provide the Markovnikov-type vinyl bromides in good yields using dibromomethane/N,N-dimethylaniline as in-situ 'HBr' source. This protocol also represents an elegant example of the activation of sp(2) C-H and C-Br bonds in one pot, in which 'HBr' is generated and transferred under mild metal-free conditions. D-incorporated experiments were employed to investigate the reaction mechanism and a plausible reaction path was proposed. (C) 2014 Elsevier Ltd. All rights reserved.
Organic synthesis using haloboration reaction. I. A simple and selective synthesis of 2-bromo- and 2-iodo-1-alkenes