Reaction Steps
Cesium fluoride (0.037 g, 0.244 mmol) was added to a solution of rac-methyl 3-methyl-4-(1-methyl-7-oxo-3-(pyridin-2-yl)-1,4,5,6,7,8-hexahydrocyclohepta[c]pyrazol-4-yl)benzoate (0.190 g, 0.488 mmol) in DME (50 mL). The mixture was stirred at rt for about 20 min then it was cooled in an ice bath and (trifluoromethyl)trimethylsilane (1.44 mL, 9.76 mmol) was added in a dropwise manner. After about 30 min, (trifluoromethyl)trimethylsilane (1.44 mL, 9.76 mmol) was added. After about 45 min, the mixture was partitioned between EtOAc (100 mL) and saturated aqueous NH4Cl solution (100 mL). The organic layer was washed with brine (100 mL), dried with Na2SO4, filtered and concentrated in vacuo. The residue was dissolved in EtOAc (20 mL) and 1 M tetrabutylammonium fluoride in THF (0.54 mL, 0.54 mmol) was added. The mixture was stirred at rt for about 1 h then it was washed with saturated NH4Cl (2×50 mL) and brine (50 mL). The organic layer was dried with Na2SO4, filtered and concentrated in vacuo. The residue was purified by column chromatography (SiO2, 25-50% EtOAc/heptane) to give rac-methyl 4-((4R,7S)-7-hydroxy-1-methyl-3-(pyridin-2-yl)-7-(trifluoromethyl)-1,4,5,6,7,8-hexahydrocyclohepta[c]pyrazol-4-yl)-3-methylbenzoate (0.018 g, 8%): LC-MS (Table 1, Method g) Rt=2.28 min, m/z 460 (M+H)+; 1H-NMR (DMSO, Bruker 400 MHz) δ 8.31-8.27 (m, 1H), 7.75-7.72 (m, 1H), 7.69-7.67 (m, 1H), 7.65-7.60 (m, 1H), 7.53-7.49 (m, 1H), 7.10-7.05 (m, 1H), 6.95 (d, J=8.1 Hz, 1H), 6.30 (s, 1H), 5.22-5.14 (m, 1H), 3.85 (s, 3H), 3.76 (s, 3H), 3.34-3.32 (m, 2H), 2.62 (s, 3H), 2.20-2.08 (m, 1H), 1.98-1.90 (m, 1H), 1.86-1.74 (m, 2H). and rac-methyl 4-((4R,7R)-7-hydroxy-1-methyl-3-(pyridin-2-yl)-7-(trifluoromethyl)-1,4,5,6,7,8-hexahydrocyclohepta[c]pyrazol-4-yl)-3-methylbenzoate (0.034 g, 15%): LC-MS (Table 1, Method g) Rt=2.28 min, m/z 460 (M+H)+; 1H-NMR (DMSO, Bruker 400 MHz) δ 8.35-8.38 (m, 1H), 7.77-7.74 (m, 1H), 7.71-7.69 (m, 1H), 7.68-7.63 (m, 1H), 7.57-7.52 (m, 1H), 7.14-7.10 (m, 1H), 6.96-6.93 (m, 1H), 6.18 (s, 1H), 5.51-5.45 (m, 1H), 3.90 (s, 3H), 3.76 (s, 3H), 3.36-3.17 (m, 2H), 2.56 (s, 3H), 2.29-2.20 (m, 1H), 1.90-1.79 (m, 1H), 1.76-1.65 (m, 2H).
