Sodium Bicarbonate → (+/-)-2-(Cyclohex-2-en-1-yl)-5-{[4-(1H-pyrazol-1-yl)phenyl]methyl}-2,5-dihydro-3H-pyrazolo[4,3-c]quinolin-3-one

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Reaction Steps

(±)-2-(trans-2-Hydroxycyclohexyl)-5-{[4-(1H-pyrazol-1-yl)phenyl]methyl}-2,5-dihydro-3H-pyrazolo[4,3-c]quinolin-3-one (Example 508, 78 mg, 0.18 mmol) was suspended in dichloromethane (3 mL) and treated with bis[α,α-bis(trifluoromethyl)benzyloxy]diphenylsulfur (Martin's sulfurane, 0.18 g, 0.27 mmol, 1.5 equiv). After stirring for 1 hour, additional Martin's sulfurane (75 mg, 0.18 mmol, 1 equiv) was added and the mixture was stirred at ambient temperature for an additional 16 hours. The mixture was then placed into an oil bath preheated to 45° C. for 6 hours, cooled to ambient temperature, treated with sodium bicarbonate (1.5 mL, aqueous saturated) and stirred vigorously for 30 minutes. The mixture was poured into sodium bicarbonate (50 mL, aqueous saturated) and extracted with dichloromethane (2×75 mL). The combined organic extracts were dried with sodium sulfate, filtered and concentrated in vacuo. The residue was purified by silica gel gradient chromatography (100:0 90:10; dichloromethane:methanol), providing partially purified material. The mixture was purified by preparative reverse phase HPLC (80:20 to 25:75; water containing 0.1% trifluoroacetic acid:acetonitrile containing 0.1% trifluoroacetic acid). The appropriate fractions were poured into sodium bicarbonate (15 mL, aqueous saturated) and extracted once with ethyl acetate (30 mL). The organic layer was dried with sodium sulfate, filtered and concentrated in vacuo, providing the titled compound: 1H-NMR (400 MHz, CDCl3) δ 8.44 (1H, dd, J=4.6, 2.0 Hz), 8.42 (1H, s), 7.89 (1H, d, J=2.6 Hz), 7.72 (1H, d, J=1.8 Hz), 7.70 (2H, d, J=8.6 Hz), 7.46-7.43 (2H, m), 7.41-7.37 (1H, m), 7.28-7.28 (2H, m), 6.47 (1H, dd, J=2.4, 1.9 Hz), 6.03-5.98 (1H, m), 5.75 (1H, br d, J=9.8 Hz), 5.47 (2H, s), 5.29-5.22 (1H, m), 2.30-2.20 (1H, m), 2.14-1.98 (4H, m), 1.85-1.73 (1H, m) ppm; high resolution mass spectrometry (ES+) m/z 422.1981 [(M+H)+; calculated for C26H24N5O: 422.1975].

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