Add sodium triacetoxyborohydride (0.40 g, 1.89 mmol) to a mixture of 3-fluoro-5-trifluoromethyl benzaldehyde (0.096 mL, 0.69 mmol), acetic acid (0.030 mL, 0.625 mmol)) and (S)-tert-Butyl 5-amino-7-methyl-8-trifluoromethyl-2,3,4,5-tetrahydrobenzo[b]azepine-1-carboxylate (Example 3, Step 13) (0.215 g, 0.63 mmol) in dichloroethane (3.0 mL). Stir the mixture at room temperature under an atmosphere of nitrogen for 20 h. Add a saturated solution of sodium bicarbonate, separate the layers and extract the aqueous layer with dichloromethane. Dry the combined organic layers over anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure. Purify the residue by flash chromatography, eluting with hexanes/ethyl acetate (gradient eluent, 0-30% ethyl acetate in hexane), to afford the title compound (0.32 g, 98%). MS (ES+): 521 (M+H).
