Acetic Acid → 6-Chloro-4-(1-((4-(4-fluorophenyl)-1-methylpiperidin-4-yl)methoxy)ethyl)-1-methyl-1h-benzo[d]imidazol-2(3h)-one trifluoroacetic acid salt

Participants

Reaction Steps

tert-Butyl 4-((1-(6-chloro-1-methyl-2-oxo-3-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydro-1H-benzo[d]imidazol-4-yl)ethoxy)methyl)-4-(4-fluorophenyl)piperidine-1-carboxylate (16.5 mg, 0.025 mmol) was dissolved in trifluoroacetic acid (40% in dichloromethane, 1 mL) and stirred at room temperature for 1 h. The reaction was concentrated and loaded onto a strong cation exchange cartridge in methanol. The cartridge was flushed with several volumes of methanol which were discarded. The crude piperidine was eluted with 2M ammonia in methanol and concentrated. The crude product was dissolved in acetonitrile (1 mL) and treated with formalin (50 μL) followed quickly by sodium cyanoborohydride (3.2 mg, 0.05 mmol). To this was added two small drops of acetic acid over 5 minutes. The reaction was concentrated and the residue taken up in ethyl acetate, washed with saturated sodium bicarbonate, then brine, dried over magnesium sulfate, and concentrated. The crude product was dissolved in ethanol (10 mL) and heated at reflux overnight. The reaction was concentrated and purified by preparative HPLC (28% B isocratic method, TFA/ACN) to give 9.0 mg (64%) as a colorless film. 1H-NMR (CD3OD, 500 MHz) δ 7.43 (dd, J=8.9, 4.9 Hz, 1.5H), 7.33 (dd, J=8.9, 5.2 Hz, 0.5H), 7.13 (m, 1.5H), 7.04 (m, 1.5H), 6.72 (d, J=1.8 Hz, 0.7H), 6.67 (d, J=1.8 Hz, 0.3H), 4.5 1 (q, J=6.4 Hz, 1H), 3.15-3.52 (m, 9H), 2.40-3.00 (m, 7H), 2.08 (m, 2H), 1.38 (d, J=6.4 Hz, 3H). Mass spec.: 432.1 (MH)+.

Provenance & Evidence