Add 3,5-bis(trifluoromethyl)benzylamine (423 mg, 1.62 mmol) followed by titanium isopropoxide (645 mg, 2.27 mmol) to 6-Methyl-5-oxo-2,3,4,5-tetrahydro-benzo[b]azepine-1-carboxylic acid isopropyl ester (423 mg, 1.62 mmol) at room temperature under an atmosphere of nitrogen and stir the solution for 14 h. Add methanol (6.7 mL) and sodium borohydride (92 mg, 2.43 mmol) and stir the mixture under nitrogen at room temperature for 45 min. Add 0.1M NaOH, stir for 30 min. Filter through celite and wash the residue with AcOEt. Separate organic layer, extract aqueous with AcOEt. Wash organic layer with brine and dry the 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, to afford (+/−)-5-(3,5-Bis-trifluoromethyl-benzylamino)-6-methyl-2,3,4,5-tetrahydro-benzo[b]azepine-1-carboxylic acid isopropyl ester (27 mg, 3%). Add acetic anhydride (0.037 mL, 0.39 mmol) dropwise to a solution of the amine (27 mg, 0.055 mmol) and pyridine (0.038 mL, 0.43 mmol) in dichloromethane (0.5 mL). Stir under nitrogen at room temperature for 14 h. Add 1 M hydrochloric acid and extract with dichloromethane. Dry the organic layer over anhydrous sodium sulfate, filter and remove the solvent under reduced pressure. Purify the residue by flash chromatography, eluting with hexanes/ethyl acetate, to afford the title compound (28 mg, 96%); MS (ES+): 531 (M+H).
