Hydrochloric Acid → tert-butyl (2-(1-methyl-1H-pyrazol-4-yl)-2-(6-(trifluoromethyl)pyridin-3-yl)ethyl)carbamate

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Ethyl 3-(1-methyl-1H-pyrazol-4-yl)-3-(6-(trifluoromethyl)pyridin-3-yl)propanoate (1.15 g, 3.51 mmol) was mixed with trimethylsilanol, sodium salt solution in THF (30 ml, 30.0 mmol, 1 molar) and stirred for 24 hours at room temperature. Trimethylsilanol, sodium salt solution in THF (30 ml, 30.0 mmol, 1 molar) added and mixture stiffed overnight at room temperature, LCMS shows incomplete comversion and reaction heated at reflux for 3 hours. The mixture was cooled on an ice bath and HCl in Et2O (48.0 g, 40 ml, 80 mmol, 2 molar) was added and after 10 min the mixture was concentrated in vacuo. The crude reaction mixture was then suspended dry THF (150 mL) and the solid filtred off. The liquid phase was concentrated in vacuo and used for next step without purification. 3-(1-methyl-1H-pyrazol-4-yl)-3-(6-(trifluoromethyl)pyridin-3-yl)propanoic acid (0.531 g, 1.774 mmol) dissolved in tert-butanol (10 ml. TEA (0.395 g, 0.544 ml, 3.90 mmol) and diphenylphosphoryl azide (0.59 g, 0.46 ml, 2.1 mmol) were added. Heated at 80° C. for 29 hours. The reaction was poured into H2O (50 mL) and extracted with EA (3×50 mL), the combined org. phases washed with brine, dried over MgSO4, concentrated in vacuo and purified by flash chromatography to yield 49 mg (7%) tert-butyl (2-(1-methyl-1H-pyrazol-4-yl)-2-(6-(trifluoromethyl)pyridin-3-yl)ethyl)carbamate.

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