Ethyl 2-methyl-4-(piperidin-1-yl)-1,8-naphthyridine-3-carboxylate (120.0 mg, 0.4 mmol) was dissolved in EtOH. NaOH (4.0 ml of a 1.0 M aq. solution) was added and the mixture refluxed for 3.0 days. The mixture was cooled, acidified with aq. HCl (1.0 M) and concentrated to dryness. The residue was suspended in anhydrous THF, N-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide hydrochloride (84.34 mg, 0.44 mmol), 1-hydroxybenzotriazole hydrate (30.74 mg, 0.2 mmol.) and Et3N (54.8 μl, 0.4 mmol) were added. The mixture was stirred at room temperature for 30 min. 3-(trifluoromethyl)benzyl amine (57.33 μl, 0.4 mmol) was added to the mixture and stirring continued for 18 h. H2O was added to the mixture and the product extracted with EtOAc, dried over MgSO4 and concentrated. Purification was done by flash chromatography (CH2Cl2/MeOH 98:2→96:4) giving 20.0 mg (12%) of the title compound.
