Oxidative bromination of ketones using ammonium bromide and oxone®

A highly efficient, environmentally safe and economic method for selective alpha-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and beta-keto esters and alpha,alpha-dibromination of 1,3-diketones and beta-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone (R) as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted alpha-position predominantly. Aromatisation of tetralones is also carried out with this reagent system. (C) 2011 Elsevier Ltd. All rights reserved.