Methyl (1S,2R,3S,4R)-3-aminobicyclo[2.2.1]heptane-2-carboxylate hydrochloride (prepared as described in Example 6c, 0.32 g, 1.58 mmol) was dissolved in methanol (8 mL). Sodium acetate (0.26 g, 3.16 mmol) was added followed by 4 Å powdered molecular sieves (0.33 g) and 3,4-difluoro benzaldehyde (0.17 mL, 1.58 mmol). Sodium cyanoborohydride (0.22 g, 3.16 mmol) was added and the mixture was stirred at 25° C. for 16 h. The mixture was poured into a mixture of saturated aqueous sodium bicarbonate solution (20 mL) and ethyl acetate (30 mL). After shaking, both layers were passed through a plug of Celite. The organic layer was further washed with saturated aqueous sodium bicarbonate solution (10 mL), saturated aqueous brine solution (10 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to afford the crude product, methyl (1S,2R,3S,4R)-3-(3,4-difluoro-benzylamino)-bicyclo[2.2.1]heptane-2-carboxylate (0.36 g, 1.22 mmol, 78%), as a clear oil. LC-MS (ESI) calcd for C16H19F2NO2 295.32, found 296.3 [M+H+].
