Hydrochloric Acid → 6-Methyl-2-(2-((pyridin-3-yloxy)methyl)piperazin-1-yl)benzo[d]oxazole hydrochloride

4 M HCl in 1,4-dioxane (6 mL, 24 mmol) was added to a solution of tert-butyl 4-(6-methylbenzo[d]oxazol-2-yl)-3-((pyridin-3-yloxy)methyl)piperazine-1-carboxylate di-TFA salt (91.1 mg, 0.140 mmol) in MeOH (1 mL). After 2 h, 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 brine (20 mL) was added. This was extracted with EtOAc (3×). The combined organics were dried over Na2SO4, filtered, and concentrated under reduced pressure, yielding 33.0 mg of the free-base of the desired product. The material was dissolved in MeOH (1 mL) and 4 M HCl in 1,4-dioxane (0.025 mL) was added. The mixture was concentrated under reduced pressure to give 35.5 mg (70%) of the desired product as the hydrochloride salt. LC-MS: RT=4.40 min, [M+H]+=325.1.