Hydrochloric Acid → (+/-)-9-[Acetyl-(3,5-bis-trifluoromethyl-benzyl)-amino]-2,3,6,7,8,9-hexahydro-1H-5-aza-cyclohepta[f]indene-5-carboxylic acid isopropyl ester

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Reaction Steps

Add 3,5-bis(trifluoromethyl)benzylamine (187 mg, 0.77 mmol) followed by titanium isopropoxide (835 mg, 2.94 mmol) to 9-Oxo-2,3,6,7,8,9-hexahydro-1H-5-aza-cyclohepta[f]indene-5-carboxylic acid isopropyl ester (200 mg, 0.7 mmol) at room temperature under an atmosphere of nitrogen and stir the solution for 3 days. Add methanol (3 mL) and sodium borohydride (40 mg, 1.05 mmol) and stir the mixture under nitrogen at room temperature for 16 hours. Add sodium bicarbonate saturated solution. 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 silica cartridge, eluting with hexanes/ethyl acetate 9:1, to afford of (+/−)-9-(3,5-bis-trifluoromethyl-benzylamino)-2,3,6,7,8,9-hexahydro-1H-5-aza-cyclohepta[f]indene-5-carboxylic acid isopropyl ester (220 mg). Add acetic anhydride (0.22 mL, 2.33 mmol) dropwise to a solution of the amine (80 mg, 0.155 mmol) and pyridine (0.18 mL, 2.33 mmol) in dichloromethane (1 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 silica gel cartridge, eluting with hexanes/ethyl acetate 4:1, to afford the title compound (64 mg, 74%); MS (ES+): 579 (M+H+Na).

Provenance & Evidence