Reaction Steps
Sodium triacetoxyborohydride (140 mg, 0.66 mmol) was added to a solution of (RS)-3,3-difluoro-4-methylpiperidine hydrochloride (Description 60, 67 mg, 0.44 mmol), (RS)-α-methyl-N-(4-oxo-1-phenylcyclohexyl)-3,5-bis(trifluoromethyl)benzeneacetamide (Example 3, 150 mg, 0.33 mmol) and triethylamine (110 mL, 0.88 mmol) in dichloroethane (30 mL) and the mixture was stirred at room temperature for 72 hours. Saturated aqueous sodium hydrogen carbonate (3 mL) and dichloromethane (5 mL) were added and the layers were separated. The organic fraction was poured onto an SCX cartridge (Varian Bond Elut™; 10 mL/500 mg). The cartridge was washed with methanol (4×2 mL), then eluted with methanolic ammonia (2M, 2×2 mL). The solvent was evaporated under reduced pressure and the residue was purified by flash column chromatography on silica gel, eluting with CH2Cl2/MeOH/NH3(Aq.) (95:5:1), to give trans-(RS)-α-methyl-N-[4-(3-fluoro-1,2,5,6-tetrahydro-4-methylpyrid-1-yl)-1-phenylcyclohexyl]-3,5-bis(trifluoromethylbenzeneacetamide (16 mg, 7%); 1H NMR (360 MHz, CD3OD) δ 1.33 (3H, d, J 6.5 Hz), 1.35–2.05 (9H, m), 1.63 (3H, s), 2.36–2.63 (4H, m), 2.74–2.78 (1H, m), 2.95–3.05 (1H, m), 3.83 (1H, q, J 7.2 Hz), 7.12–7.39 (5H, m), 7.79 (2H, s), and 7.81 (1H, s); m/z (ES+) 557 (M+1); cis-(RS)-α-methyl-N-[4-(3-fluoro-1,2,5,6-tetrahydro-4-methylpyrid-1-yl)-1-phenylcyclohexyl]-3,5-bis(trifluoromethylbenzeneacetamide (12 mg, 5%); 1H NMR (400 MHz, CD3OD) δ 1.22–1.28 (1H, m), 1.44 (3H, d, J 6.8 Hz), 1.43–1.54 (1H, m), 1.62 (3H, s), 1.72–1.85 (4H, m), 2.00–2.09 (2H, m), 2.42–2.61 (5H, m), 2.91–3.00 (2H, m), 4.02 (1H, q, J 6.8 Hz), 7.12–7.28 (5H, m), 7.94 (2H, s), and 8.14 (1H, s);. m/z (ES+) 557 (M+1); (2R*,4′R*)-trans-, (2S*,4′R*)-trans-, (2R*,4′R*)-cis-, and (2S*,4′R*)-cis-α-methyl-N-[4-(3,3-difluoro-4-methylpiperidin-1-yl)-1-phenylcyclohexyl]-3,5-bis(trifluoromethylbenzeneacetamide as a mixture of diastereoisomers (13 mg, 5%); 1H NMR (360 MHz, CD3OD) δ 1.36 (3H, d, J 7.2 Hz), 1.45 (3H, d, J 6.8 Hz), 1.53–1.83 (6H, m), 1.84–1.98 (2H, m), 2.09–2.25 (2H, m), 2.37–2.51 (2H, m), 2.58–2.92 (3H, m), 2.98–3.03 (1H, m), 3.89 and 4.09 (total 1H, each q, J 7.2 Hz)}, 7.13–736 (5H, m), and 7.80–8.18 (3H, m); m/z (ES+) 577 (M+1).
