Hydrochloric Acid → 1-[4-(4,5-Dihydro-5-phenyl-3-isoxazolyl)-2-thiazolyl]piperazine hydrochloride

To a solution of 1,1-dimethylethyl 4-[4-(4,5-dihydro-5-phenyl-3-isoxazolyl)-2-thiazolyl]-1-piperazineacetate (i.e. the product of Example 7, Step D) (0.7 g, 1.686 mmol) in diethyl ether (10 mL) was added a 2 M solution of hydrogen chloride in methanol (10 mL) at room temperature. The reaction mixture was stirred at room temperature for 8 h. The resulting white precipitate was filtered and dried to give 500 mg of the title compound as a white solid.