A mild and environmentally acceptable synthetic protocol for chemoselective α-bromination of β-keto esters and 1,3-diketones

A wide variety of unsubstituted beta-keto esters can be brominated chemoselectively to the corresponding alpha-monobromo-beta-keto esters by Using a combination of vanadium pentoxide, hydrogen peroxide and ammomium bromide in a biphasic system, dichloromethane-water at 0-5 degrees C. In addition, alpha-mono substituted beta-keto esters, cyclic P-keto-esters and 1,3-diketones can also be brominated selectively using the same protocol. (c) 2006 Elsevier Ltd. All rights reserved.