4-[2-(2,4-Difluoro-phenyl)-1-methoxycarbonyl-2-oxo-ethylcarbamoyl]-piperidine-1-carboxylic acid benzyl ester → 4-[5-(2,4-Difluoro-phenyl)-4-methoxycarbonyl-oxazol-2-yl]-piperidine-1-carboxylic acid benzyl ester

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Reaction Steps

To a 1 liter round bottom flask fitted with a condenser, nitrogen inlet, and magnetic stir bar is added 4-[2-(2,4-Difluoro-phenyl)-1-methoxycarbonyl-2-oxo-ethylcarbamoyl]-piperidine-1-carboxylic acid benzyl ester, (32 g, 67.4 mmol), and 120 mL of thionyl chloride. The mixture is immersed in an oil bath preheated to 70° C. and stirred for 10 minutes. The reaction is removed, cooled to room temperature and concentrated to an amber oil. The amber oil is carefully treated with about 50 g of ice, and 350 mL of saturated sodium bicarbonate. The resulting mixture is extracted with 3×100 mL of diethyl ether. The organic layers are combined, washed with brine, dried over magnesium sulfate and concentrated to a thick amber paste to yield the title compound.

Provenance & Evidence