Hydrochloric Acid → 1-(3-Pyridin-2-yl-1,2,4-thiadiazol-5-yl)piperazine

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Reaction Steps

tert-Butyl 4-(3-pyridin-2-yl-1,2,4-thiadiazol-5-yl)piperazine-1-carboxylate (6.35 g, 17.0 mmol) was dissolved in tetrahydrofuran (100 ml), and a solution of 4 N hydrogen chloride in ethyl acetate (50 ml) was added thereto, followed by stirring at room temperature for 5 hours. Hexane (250 ml) was poured to the reaction mixture, and a solid was separated by filtration. The obtained solid was dissolved in an aqueous saturated sodium hydrogen carbonate solution, followed by stirring at room temperature for 2 hours. Water was poured to the reaction mixture, and the resulting solution was extracted with a mixed solution of ethyl acetate/tetrahydrofuran (1:1). The extract was washed with water and dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. Hexane was added to the residue, and 2.79 g (67.0%) of the desired product as a solid was separated by filtration.

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