Hydrochloric Acid → (4-Phenyl-4,5,6,7-tetrahydro-benzothiazol-2-yl)-piperidin-4-yl-amine dihydrochloride

To a solution of 4-(4-phenyl-4,5,6,7-tetrahydro-benzothiazol-2-ylamino)-piperidine-1-carboxylic acid tert-butyl ester (1.575 g, 3.8 mmol) in methylene chloride (13.8 mL) was added 2 M HCl solution in diethyl ether (6.9 mL). The reaction was stirred at room temperature over the weekend. The solvent was removed under reduced pressure and the residue was treated with diethyl ether and evaporated. The title compound was obtained as a light yellow solid (1.32 g, 90%).