Hydrochloric Acid → 1-(1,2-Diamino-1-methylethyl)-1-cyclopropanecarboxylate dihydrochloride

0.82 g (3.83 mmol) of the crude tert-butyl 1-(1,2-diamino-1-methyl ethyl)-1-cyclopropanecarboxylate was dissolved in concentrated hydrochloric acid (5 mL) at room temperature, and the solution was stirred at the same temperature for 30 minutes. After adding water to the reaction solution, the solvent was removed by distillation under reduced pressure. The residue was azeotropically distilled with ethanol (twice) to obtain 0.82 g (3.55 mmol, 93%) of the crude target compound as a pale yellow foam solid. The thus obtained crude product was used in the subsequent reaction with no further purification.