1,4-Dioxane hydrochloride → N-(4-{2-[2-(acetylamino)-1,3-thiazol-4-yl]ethyl}benzyl)hydrazinecarboxamide hydrochloride

To a suspension of tert-butyl 2-[(4-{2-[2-(acetylamino)-1,3-thiazol-4-yl]ethyl}benzyl)carbamoyl]hydrazinecarboxylate (281.8 mg, 0.65 mmol) in anhydrous dichloromethane (3.25 ml) was added 4M-hydrogen chloride dioxane solution (3.25 ml, 13.0 mmol). After stirring at room temperature for 1 hr, the reaction mixture was concentrated under reduced pressure. Ethyl acetate was added to the residue, and the mixture was concentrated again under reduced pressure. The operation was performed 3 times to remove hydrogen chloride gas azeotropically. The residue was suspended in ethyl acetate and filtered. The filtered product was washed with ethyl acetate, and dried under reduced pressure to give the title compound (245.1 mg, quantitative) as a white solid.