Reaction Steps
To a round bottom flask was added 1-((1R,2R)-2-((S)-1-(4-nitrophenyl)piperidin-3-ylamino)cyclohexyl)-3-phenylurea (prepared as described in Example 1) (30 mg, 0.069 mmol), formaldehyde (0.079 mL, 1.028 mmol) (37% in water), acetic acid (0.2 mL), CH2Cl2 (1 mL) and NaSO4 (3 gms). The reaction was stirred at rt for 2 hrs. Then sodium cyanoborohydride (21.54 mg, 0.343 mmol) was added to the reaction and the reaction was stirred for an additional 1 hr. After this time, the reaction was quenched with water (2 ml). The reaction was partitioned between CH2Cl2 (15 ml) and saturated aqueous NaHCO3 (10 ml). The organic layer was washed with water (10 ml) and saturated aqueous NaCl (10 ml). The organic layer was dried over MgSO4, filtered and concentrated. The residue was purified by RP prep-HPLC (Method A). The desired fractions were concentrated to give the product, 1-((1R,2R)-2-(methyl((S)-1-(4-nitrophenyl)piperidin-3-yl)amino)cyclohexyl)-3-phenylurea (18 mg, 0.038 mmol, 55.2% yield) as a yellow solid. Anal. Calcd. for C25H33N5O3 m/z 451.5, found: 452.3 (M+H)+; 1H NMR (500 MHz, CDCl3) δ ppm 10.60 (br. s., 1H), 7.89 (d, J=8.80 Hz, 2H), 7.52 (br. s., 1H), 7.33 (d, J=8.25 Hz, 2H), 7.30-7.19 (m, 2H), 7.03 (t, J=7.15 Hz, 1H), 6.75 (d, J=8.80 Hz, 2H), 3.87-3.56 (m, 4H), 3.51-3.34 (m, 4H), 3.23-3.13 (m, 1H), 2.82 (br. s., 3H), 2.25-1.32 (m, 10H); 13C NMR (126 MHz, CDCl3) δ ppm 158.25, 154.02, 139.91, 138.67, 128.85, 125.71, 123.04, 118.88, 114.37, 68.41, 60.22, 50.63, 48.67, 48.25, 32.33, 31.60, 25.29, 25.13, 24.18, 23.74, 22.28.
