Reaction Steps
To a stirred solution of 1-(3-oxo-propyl)-3-(4-trifluoromethyl-phenyl)-1,4,6,7-tetrahydro-pyrazolo[4,3-c]pyridine-5-carboxylic acid tert-butyl ester (0.99 g, 23.6 mmol) in CH2Cl2 (20 mL) were added 1-methyl-3-piperidin-4-yl-1,3-dihydro-benzoimidazol-2-one (0.60 g, 25.9 mmol) and glacial AcOH (0.13 mL, 23.6 mmol) in that order and stirred for 20 min. NaBH(OAc)3 (0.65 g, 30.6 mmol) was added and stirred under nitrogen for 2 h. Saturated NaHCO3 (20 mL) was added and stirred for 30 min, and the layers were separated. The organic extract was washed with brine, dried over Na2SO4, and concentrated under reduced pressure. MPLC of the crude afforded the desired compound as a white solid (1.27 g, 85%). TLC (silica, 7% MeOH/CH2Cl2): Rf=0.35. MS (electrospray): exact mass calculated for C34H41F3N6O3, 638.32. m/z found, 639.3 [M+H]+, 661.2 [M+Na]+. 1H NMR (400 MHz, CDCl3): 7.81 (br d, J=8.0 Hz, 2H), 7.68 (br s, 2H), 7.25 (dd, J=1.6, 7.5 Hz, 1H), 7.15-7.07 (m, 2H), 7.02(dd, J=1.6, 7.9 Hz, 1H), 4.70 (br s, 2H), 4.38 (tt, J=4.2, 12.4 Hz, 1H), 4.18 (t, J=6.8 Hz, 2H), 3.82 (s, 2H), 3.45 (s, 3H), 3.07 (d, J=11.6 Hz, 2H), 2.84 (t, J=5.5 Hz, 2H), 2.53-2.42 (m, 2H), 2.44 (t, J=6.7 Hz, 2H), 2.21-2.03 (m, 4H), 1.84 (d, J=12.0 Hz, 2H), 1.52 (s, 9H).
