Pyridine → (2R)-1-((tert-butoxy)carbonyl)-4-oxopyrrolidine-2-carboxylic acid

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Reaction Steps

6.1 12.2 g (122 mmol) of chromium(VI) oxide are added to a mixture, held at 0° C., of 22 ml of pyridine and 50 ml of dichloromethane, and the mixture is stirred at the same temperature for 30 minutes. The solution is allowed to warm to room temperature, and a solution of 5.00 g of cis-Boc-4-hydroxy-D-proline in 80 ml of dichloromethane is added dropwise over the course of 5 minutes. After stirring at room temperature for 1 hour, the solution is filtered, and the filtrate is evaporated. The residue is partitioned between 1N HCl and tert-butyl methyl ether. The organic phase is dried over sodium sulfate, evaporated and recrystallised from diethyl ether/petroleum ether, giving Boc-4-keto-D-proline as a colourless solid; ESI 130.

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