Tert-butyl 3-(((2,3-dihydro(1,4)dioxino(2,3-c)pyridin-7-ylmethyl)(trifluoroacetyl)amino)methyl)piperidine-1-carboxylate → N-(2,3-dihydro(1,4)dioxino(2,3-c)pyridin-7-ylmethyl)-2,2,2-trifluoro-N-(piperidin-3-ylmethyl)acetamide

To a solution of 0.43 g of tert-butyl 3-(((2,3-dihydro(1,4)dioxino(2,3-c)pyridin-7-ylmethyl)(trifluoroacetyl)amino)methyl)piperidine-1-carboxylate in 3 mL of chloroform, 3 mL of trifluoroacetic acid was added, and the mixture was stirred at room temperature for 1 hour 40 minutes. The solvent was distilled off under reduced pressure. The resultant residue was charged with chloroform and water, and adjusted to pH 8.0 with an aqueous sodium hydrogen carbonate solution and a 20% aqueous sodium hydroxide solution. The organic layer was separated, and the aqueous layer was extracted with chloroform. The organic layer and the extract were combined, the resultant solution was washed with water and a saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 0.15 g of N-(2,3-dihydro(1,4)dioxino(2,3-c)pyridin-7-ylmethyl)-2,2,2-trifluoro-N-(piperidin-3-ylmethyl)acetamide as a light yellow oily substance.