Monobromomalononitrile: an efficient regioselective mono brominating agent towards active methylene compounds and enamines under mild conditions

Abstract

The potential of monobromomalononitrile (MBM) as a convenient source of cationic bromine in organic bromination reaction has been explored. Studies reveal that MBM can be a good substitute for N-bromosuccinimide (NBS) in various respects. Enamines and active methylene compounds bearing aromatic rings are selectively mono brominated on the vinylic and active methylene group respectively on reaction with MBM. This methodology has the advantages of easy preparation of MBM, shorter reaction time and high yields of the product formation. Moreover it provides a metal free green brominating agent which is more convenient for the pharmaceutical industry. Mono bromination reaction takes place only on active methylene groups even after addition of excess amount of MBM. Enamines containing electron withdrawing, electron donating and ortho substituted amines react smoothly affording only the vinylic mono bromo products in good yields without producing any side products.