Pyridine → 2-Tert-butyl 5-methyl pyridine-2,5-dicarboxylate

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Reaction Steps

5-(Methoxycarbonyl)pyridine-2-carboxylic acid (7.72 g, 42.65 mmol) was suspended in tert-butanol (70 mL) and pyridine (25 mL) and cooled in an ice-water bath. 4-Toluenesulfonyl chloride (19.4 g, 102 mmol) was added in one portion and the mixture was stirred 30 minutes in the ice-water bath. The reaction mixture was warmed to room temperature and stirred for 16 h. The reaction mixture was then slowly poured into a stirring mixture of saturated aqueous sodium bicarbonate (300 mL) and ethyl ether (150 mL). The resulting two-phase mixture was then extracted with ethyl ether (3×150 mL). The extracts were combined, washed with brine, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The crude product (5.8 g, 51% yield) was used in the next step without further purification.

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