Hydrazine → 1,1-dimethylethyl 4-[[5-(4-fluorophenyl)-4,5-dihydro-4-hydroxy-4-(4-pyridinyl)-1H-pyrazol-3-yl]methyl]-1-piperidinecarboxylate

Participants

Reaction Steps

To a solution of 1,1-dimethylethyl 4-[2-[3-(4-fluorophenyl)-2-(4-pyridinyl) oxiranyl]-2-oxoethyl]-1-piperidinecarboxylate prepared in step 4 of this Example (3.45 g, 7.8409 mmol) in ethanol (15 mL), anhydrous hydrazine (0.50 mL, 15.6818 mmol) was added. The reaction was heated to reflux overnight. The reaction solution was cooled to room temperature and ethanol was removed under reduced pressure. The resulting residue was taken into ethyl acetate, washed with water and brine, and dried over MgSO4. After filtration the solvent was removed under reduced pressure. The crude residue was purified by chromatography (silica gel, 2:1-1:1-1:2 hexane/ethyl acetate) to give 1,1-dimethylethyl 4-[[5-(4-fluorophenyl)-4,5-dihydro-4-hydroxy-4-(4-pyridinyl)-1H-pyrazol-3-yl]methyl]-1-piperidinecarboxylate (1.9187 g, 53.9%). This intermediate (1.8611 g, 4.0993 mmol) was dissolved in dry methylene chloride (40 mL) and treated with Martin sulfurane dehydrating reagent (4.13 g, 6.1490 mmol). The reaction solution was stirred at room temperature under N2 overnight, then diluted with ethyl acetate, washed with 1N sodium hydroxide solution, water and brine, dried over MgSO4. After filtration the solvents were removed. The resulting crude pruduct mixture was purified by flash chromatoghaphy (silica gel, 2:1-1:1-1:2 Hexane/ethyl acetate) to give 1,1-dimethylethyl 4-[[5-(4-fluorophenyl)-4-(4-pyridinyl)-1H-pyrazol-3-yl]methyl]-1-piperidinecarboxylate (0.6964 g, 39%).

Provenance & Evidence