N-Bromosaccharin/$Mg(ClO_4)_2$ is an effective and regioselective system for ${alpha}$-monobromination of 1,3-dicarbonyl compounds. A wide variety of ${eta}$-keto esters and 1,3-diketones in reaction with this system afforded a regioselectively ${alpha}$-monobrominated products. The bromination reaction can be conducted at 0-5 $^{circ}C$ either in solution or under solvent-free conditions.