The general procedure for the synthesis of ethyl 1-(BOC-amino)cyclopropane-1-carboxylate from di-tert-butyl dicarbonate and ethyl 1-aminocyclopropane-1-carboxylate hydrochloride was as follows: to a solution of 1-aminocyclopropane carboxylic acid ethyl ester hydrochloride (3.22 g, 19.4 mmol) in dichloromethane (35 mL) was added triethylamine (2.71 mL, 19.4 mmol) to form a suspension. A solution of dichloromethane (5 mL) of di-tert-butyl dicarbonate (4.24 g, 19.4 mmol) was added slowly and dropwise over about 5 hours. The reaction mixture was stirred overnight at room temperature. After completion of the reaction, extraction was carried out by adding 1 M aqueous KHSO4 solution (100 mL) and dichloromethane (50 mL). The organic layer was separated, dried over anhydrous sodium sulfate, the solvent was evaporated under reduced pressure and co-evaporated with tetrahydrofuran (2×) to give 4.31 g (97% yield) of ethyl 1-(BOC-amino)cyclopropanecarboxylate.
