1-((2R,4R)-2-(1H-benzo[d]imidazol-2-yl)-1-methylpiperidin-4-yl)-3-(4-cyanophenyl)urea synthesis

Yield:1095173-64-0 73%

Reaction Conditions:

Stage #1: (2R,4R)-tert-butyl 2-((2-aminophenyl)carbamoyl)-4-(3-(4-cyanophenyl)ureido)piperidine-1-carboxylatewith acetic acid at 65; for 2 h;
Stage #2: with trifluoroacetic acid at 20; for 2 h;
Stage #3: formaldehydwith water;sodium cyanoborohydride;sodium hydrogencarbonatemore than 3 stages;

Steps:

31

1-[(2R,4R)-2-(1H-benzimidazol-2-yl)-1-methylpiperidin-4-yl]-3-(4-cyanophenyl)urea; (2R,4R)-tert-butyl 2-((2-amino-phenyl)carbamoyl)-4-(3-(4-cyanophenyl)ureido)piperidine-1-carboxylate (1600 mg, 3.34 mmol) was dissolved in acetic acid (10 mL) and stirred at 65° C. for 2 hours. The reaction mixture was concentrated under reduced pressure to remove acetic acid. Trifluoroacetic acid (10 mL) was added to the residue. The resulting solution was stirred at room temperature for 2 hours. The reaction mixture was concentrated to remove TFA and the resulting product was used in the next step without further purification. 37% formaldehyde solution (1.24 mL, 16.7 mmol) in water was added to a solution of the residue in methanol (20 mL) and the reaction mixture was stirred at room temperature for 1 hour, then 1M sodium cyanoborohydride in THF (10.5 mL, 10.5 mmol) was added at 0° C. The reaction mixture was stirred at room temperature for 18 hours and the solvent was evaporated under vacuum. Saturated sodium bicarbonate solution (50 mL), water (100 mL) and ethyl acetate (200 mL) were added and the mixture was stirred about 30 min. The organic layer was separated, dried over MgSO₄, and concentrated. The resulting product was purified by Companion (ReadySep 40 g, silica gel packed) using CH₃OH/CH₂Cl₂ from 1-5% as eluent to provide the title compound as an off-white solid 915 mg (73%). LC-MS: 375.3, 373.3 (t=1.5min). ¹H NMR (acetone-D6): δ 1.81 (m, 2H), 1.9-2.05 (m, 2H), 2.10 (m, 1H), 2.17 (s, 3H), 2.52 (m, 1H), 2.94 (m, 1H), 3,86 (m, 1H), 4.2 (m, 1H), 6.4 (d, 1H), 7.16 (m, 2H), 7.52 (m, 2H), 7.60 (m, 2H), 7.62 (m, 2H), 8.46 (s, 1H).

References:

US2009/5416,2009,A1 Location in patent:Page/Page column 47; 54