Methyl chloroformate → 5-[(Tert-butoxycarbonylmethyl-methoxycarbonyl-amino)-methyl]-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-ethyl ester

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Reaction Steps

Methyl chloroformate (0.065 mL, 0.85 mmol) was added to a solution of 5-[(tert-butoxycarbonylmethyl-amino)-methyl]-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-ethyl ester (300 mg, 0.77 mmol) and 4-methylmorpholine (0.12 mL, 1.2 mmol) in dichloromethane (10 mL) at 0° C. After 15 minutes the mixture was diluted with dichloromethane (30 mL) and washed with water (15 mL), saturated ammonium chloride (15 mL) and saturated sodium chloride (15 mL). The organic phase was dried over sodium sulfate and the solvent was removed under reduced pressure to provide 5-[(tert-butoxycarbonylmethyl-methoxycarbonyl-amino)-methyl]-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-ethyl ester (304 mg, 0.68 mmol, 88%). C21H36N2O8 calculated 444.3, observed [M+1]+445.3; rt=2.58 min.

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