Benzyl chloroformate → N-[2-(ethoxycarbonyl)butyl]-N-benzyloxycarbonylalanine

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Reaction Steps

To a suspension of N-[2-(ethoxycarbonyl)butyl]alanine (2.2 g, 10 mmol) and potassium carbonate (2.2 g, 16 mmol) in a mixture of acetone (30 mL) and water (2.5 mL) was added benzyl chloroformate (2.0 mL, 2.4 g, 14 mmol) at 0-5° C. After stirring for 2 h at ambient temperature the solid was filtered off, the solvent was evaporated, the residue was stirred with cold aqueous sodium hydroxide solution [prepared from ice (20 g) and aqueous sodium hydroxide solution (1N, 40 mL)] and extracted with ethyl acetate (40 mL). The aqueous layer was acidified with an aqueous solution of hydrochloric acid 1/1 (20 mL) and the mixture was extracted with ethyl acetate (40 mL). After drying and evaporation N-[2-(ethoxycarbonyl)butyl]-N-benzyloxycarbonylalanine (1.66 g, 47%) was obtained as a yellow oil which can be used in the next reaction without further purification.

Provenance & Evidence