Chemoselective Bromination of Active Methylene and Methyne Compounds by Potassium Bromide, Hydrochloric Acid and Hydrogen Peroxide

Abstract

Abstract: Active methylene and methyne compounds can bechemoselectively brominated in high yields using potassiumbromide, hydrochloric acid, and hydrogen peroxide at room temper-ature. Key words: halogenation, halaides, green chemistry, bromination,active methylene compounds Halogenated active methylene and methyne compoundsare very important synthetic intermediates for the nucleo-philic substitutions in synthetic organic chemistry. Theclassical methods of halogenation of active methylene andmethyne compounds 1 are the reaction with bromine 1 orsulfuryl chloride, 2 however, they suffer from drawbackssuch as toxicity of the reagents, generation of acidicgasses after the reaction, or overhalogenation of thearomatic rings in 1 . Although a number of new methodsof this transformation have previously been developed,most of them have severe disadvantages such as theproduction of undesirable waste. 3–5 Khan and co-workers recently developed chemoselectivebromination of active methylene compounds by employ-ing the vanadium pentoxide catalyzed (V