Dichloromethane → 1-tert-Butyl 2-methyl (2S,4R)-4-((methanesulfonyl)oxy)pyrrolidine-1,2-dicarboxylate

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Reaction Conditions

Reaction Steps

In a 1.0 L 4-necked RB flask fitted with a mechanical stirrer and a reflux condenser and under a nitrogen blanket, 1-tert-butyl(2S,4R) 2-methyl 4-hydroxypyrrolidine-1,2-dicarboxylate (100 gm) and dichloromethane (1000 ml) were added at a temperature 25-35° C. while stirring. The reaction mixture was cooled to 0-5° C. and triethyl amine (18.2 g, 0.180M) was added. The reaction temperature was maintained for 15 min and then methane sulfonyl chloride (16.6 g, 0.145M) was added dropwise at 0-5° C. while stirring. The reaction mixture was maintained for 3-4 hr at 0-5° C. The reaction was monitored by TLC. After ascertaining the completion of the reaction, water (168 ml) was added while stirring and the layers were separated. One more dichloromethane (600 ml) extraction was given to aqueous layer. Two water washings were given to the MDC layer. The dichloromethane layer was dried over anhydrous sodium sulphate. The MDC layer (95%) was concentrated under vacuum below 45° C. After distillation n-hexane (600 ml) was added and the mixture stirred for 20 min at 0-5° C. The solid precipitate was filtered and the product was washed with hexane (200 ml). The product was dried at 40-45° C. under vacuum.

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