Hydrochloric Acid → 1-[3-(Thiophen-2-yl)-1,2,4-thiadiazol-5-yl]piperazine

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Reaction Steps

To a solution of tert-butyl 4-[3-(2-thienyl)-1,2,4-thiadiazol-5-yl]piperazine-1-carboxylate (4.30 g, 12.2 mmol) in ethyl acetate (70 ml) was added a solution of 4 N hydrochloric acid in ethyl acetate (35 ml), and the mixture was stirred at room temperature for 18 hours and half. Hexane (150 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 poured to the residue, and 2.31 g (75.0%) of the desired product as a solid was separated by filtration.

Provenance & Evidence