Triphenylphosphine (1.15 g, 4.39 mmol) and N-bromosuccinimide (0.79 g, 4.39 mmol) were added to a 0° C. solution of N-Cbz-diethanolamine (1 g, 4.18 mmol) in 40 ml of methylene chloride. The reaction was stirred at room temperature for 4 hours and then cooled to 0° C. 2,6-Lutidine (0.97 ml, 8.36 mmol) was added, followed by the dropwise addition of triisopropylsilyl triflate (1.35 ml, 5 mmol). The reaction was stirred at room temperature for 12 h, diluted with water, and concentrated under vacuum and the residue was extracted with ethyl acetate (2×50 ml). The organic layer was washed with 0.5 M HCl, saturated sodium bicarbonate, brine and dried over sodium sulfate. Evaporation of the solvent followed by chromatography (SiO2 Biotage 40 M, 3%-5% ethyl acetate/hexanes) gave (2-bromo-ethyl)-(2-triisopropylsilanyloxy-ethyl)-carbamic acid benzyl ester (400 mg) as a clear oil.
