Pyridine → 1-tert-Butyl 2-methyl (2S,4R)-4-[(4-methylbenzene-1-sulfonyl)oxy]pyrrolidine-1,2-dicarboxylate

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Reaction Steps

To a solution of (2S,4R)-4-hydroxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester (10 g, 40.77 mmol) in methylene chloride (56 mL) at 0° C. was added pyridine (30 mL), followed by dropwise addition of a solution of p-toluenesulfonyl chloride (9.4 g, 49.30 mmol) in methylene chloride. The reaction mixture was warmed to room temperature and then refluxed for 16 h. The reaction mixture was concentrated, re-dissolved in methylene chloride, and washed with water and brine. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated to give (2S,4R)-4-(toluene-4-sulfonyloxy)-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester (14.4 g, 88.4% yield) as a light yellow sticky solid. The crude was used in the next step without further purification. MS calcd. for C18H26NO7S [(M+H)+] 400.0, obsd. 400.0.

Provenance & Evidence