Acetic Anhydride → 1-(4-(6-Methoxybenzo[d]thiazol-2-yl)-3-((pyridin-3-yloxy)methyl)piperazin-1-yl)ethanone dihydrochloride

Acetic anhydride (0.100 mL) was added to a solution of 6-methoxy-2-(2-((pyridin-3-yloxy)methyl)piperazin-1-yl)benzo[d]thiazole hydrochloride (73.2 mg, 0.186 mmol) in THF (2 mL), and the mixture was heated to 70° C. for 2 h. Upon cooling to rt, the reaction mixture was concentrated under reduced pressure and purified by HPLC (5 to 50% MeCN/0.1% TFA in H2O/0.1% TFA gradient). The fractions containing the desired product were brought to pH 12 with 1 N NaOH and were extracted with EtOAc (3×). The combined organics were dried over Na2SO4, filtered, and concentrated under reduced pressure. The material was dissolved in MeOH (1 mL) and treated with 4 M HCl in 1,4-dioxane (6 mL). This was concentrated under reduced pressure, yielding 74.3 mg (85%) of the title compound as a white solid. LC-MS: RT=6.10 min, [M+H]+=399.0.