To a solution of (5-bromo-3-chloro-2-fluoro-benzyl)-carbamic acid tert-butyl ester (3 g, 8.86 mmol) in DMF (45 mL) was added zinc cyanide (1.04 g, 8.86 mmol) and Pd(Ph3P)4 (1.02 g, 0.886 mmol). The reaction mixture was stirred at 120° C. for 15 min in a microwave apparatus (Personal Chemistry, Biotage). After cooling to RT, the mixture was filtered through Celite and rinsed down with EtOAc. The filtrate was washed with saturated aqueous NH4Cl solution (4×75 mL), dried (Na2SO4) and evaporated in vacuo. Purification by flash column chromatography on silica gel (eluent gradient: c-hexane/EtOAc 9:1 to 3:1) afforded the title compound as white solid. TLC Rf (c-hexane/EtOAc 3:1)=0.35; tR (HPLC conditions c): 5.28 min.
