1211518-35-2

Methyl 6-Chloro-5-(trifluoromethyl)picolinate is used in preparation of pyridine amides as cannabinoid CB2 receptor agonists.

Methyl oxo-5-trifluoromethylpyridine-2-carboxylate (2.2 g, 10 mmol) was added batchwise to phosphoric acid trichloride (CAS 10025-87-3, 10 mL) at 0 °C, the reaction mixture was stirred and reacted at 50 °C overnight. Upon completion of the reaction, the solvent was removed by vacuum distillation to give a brown oil. The oily substance was dissolved in ethyl acetate (30 mL) and minimally neutralized with aqueous sodium carbonate. The neutralized mixture was extracted with ethyl acetate (2 x 30 mL), the organic phases were combined and washed with brine (30 mL), dried over anhydrous sodium sulfate, filtered and concentrated to give a light brown solid. Purification of the above solid by column chromatography (silica gel, 15 g, 3% petroleum ether solution of ethyl acetate) resulted in methyl 6-chloro-5-(trifluoromethyl)pyridinecarboxylate (1.5 g, 63% yield) as a white solid; mass spectrum (EI): m/e = 240.0 [M + H]+.

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