2-methylpropyl 6-(4-{[2-(3-fluorophenyl)-4-oxopiperidin-1-yl]carbonyl}-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl)-1H-imidazo[4,5-b]pyridine-1-carboxylate (0.19 g, 0.32 mmol) and potassium carbonate (0.20 g, 1.4 mmol) in methanol (10 mL) was stirred for 45 minutes at 25° C. The mixture was diluted with ethyl acetate (80 mL) washed with water (50 mL) and brine (25 mL), then dried over anhydrous sodium sulfate, filtered and concentrated. The residue was chromatographed on silica gel (methanol/ethyl acetate 1:10). Residue obtained by the concentration of product containing fractions was stirred 18 hours at 25° C. in diethyl ether (20 mL) and the solid product thus formed was isolated by filtration to give 2-(3-fluorophenyl)-1-{[7-(3H-imidazo[4,5-b]pyridin-6-yl)-2,3-dihydro-1,4-benzoxazepin-4(5H)-yl]carbonyl}piperidin-4-one (0.45 g, 27% yield). 1H NMR (400 MHz, d6-DMSO): 8.62 (s, 1H), 8.47 (s, 1H), 8.18 (s, 1H), 7.69 (d, 1H), 7.57 (d, 1H), 7.24 (q, 1H), 7.10-7.01 (m, 4H), 5.19 (t, 1H), 4.61 (m, 2H), 4.24 (m, 2H), 3.72 (m, 3H), 3.41 (m, 2H), 2.84 (m, 2H), 2.61 (m, 1H), 2.34 (d, 1H); MS (EI) for C27H24FN5O3: 486 (MH+).
