The solution of 68.9 g (0.29 mol) of tert-butyl (1S)-2-hydroxy-1-phenylethylcarbamate and triethylamine (40.36 mL, 0.29 mol) in 700 mL of dry dichloromethane under inert atmosphere was cooled to −10° C. and 24.79 mL (0.319 mol) of mesylchloride were added dropwise. After 2 hours at 0° C. the mixture was poured into ice and water and extracted with dichloromethane. The organic phase was washed with diluted HCl, aqueous NaHCO3, brine and dried over Na2SO4 yielding 89.8 g of the product (98% yield).
