A solution of 3 g of (4-bromo-phenyl)-(2-methyl-4-methoxyphenyl)-methanone (prepared from 3-methylanisole and 4-bromobenzoyl chloride by Friedel-Crafts reaction analogously to Ex. 14a) in 100 ml of tetrachloromethane is treated with 2.1 g of N-bromosuccinimide and a spatula tip of dibenzoyl peroxide. The reaction mixture is stirred at room temperature for 6 hrs. under irradiation, subsequently diluted with 100 ml of methylene chloride and washed in succession with saturated sodium hydrogen carbonate solution and saturated sodium chloride solution. The organic phase is dried, filtered and immediately reacted. The solution is added dropwise to a mixture, previously stirred at 0° C., of 2.13 g of tert-butyl N-hydroxy-carbamate and 0.38 g of sodium hydride in 30 ml of TMF. The reaction mixture is warmed to room temperature and stirred. For the working-up, the mixture is treated with 60 ml of saturated ammonium chloride solution and the separated organic phase is washed with saturated sodium chloride solution, dried over sodium sulphate and concentrated. After chromatography of the residue (silica gel, ethyl acetate-hexane, 10:90 to 25:75) there are obtained 2.65 g of tert-butyl [2-(4-bromo-benzoyl)-5-methoxy-benzyloxy]-carbamate, MS: m/e 436 (M+H+, 1 Br).
