Cesium carbonate → 6-Chloro-5-(3,3-difluoro-pyrrolidin-1-yl)-pyridine-2-carboxylic acid methyl ester

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Under nitrogen atmosphere, a suspension of 5-bromo-6-chloro-pyridine-2-carboxylic acid methyl ester (Example 9 c, 1.5 g, 6 mmol), 3,3-difluoropyrrolidine hydrochloride (CAN 163457-23-6, 0.64 g, 6 mmol), tris(dibenzylideneacetone)dipalladium (CAN 51364-51-3, 120 mg, 0.12 mmol), (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (CAN 76189-55-4, 150 mg, 0.24 mmol) and cesium carbonate (3.9 g, 12 mmol) in toluene (30 mL) was stirred at 110° C. overnight. After concentration, the residue was partitioned between water (30 mL) and ethyl acetate (30 mL). The aqueous phase was extracted with ethyl acetate (2×30 mL). The combined organic phase was washed with brine (30 mL), dried over anhydrous sodium sulfate, filtered and concentrated to give the crude product. The crude product was purified by column chromatography (silica gel, 15 g, 10% ethyl acetate in petroleum ether) to give the target compound (0.5 g, 30%) as light-yellow solid; MS (EI): m/e=277.0 [M+H]+.

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