1-[1-(Diphenylmethyl)azetidin-3-yl]piperidine-4-carboxylic acid (0.35 g, 0.9 mmol) was dissolved in DMF (8 mL) and to the solution were added TBTU (0.39 g, 1.2 mmol), DIPEA (0.21 mL, 1.2 mmol) and a solution of dimethylamine (3.0 mL, 2M in THF, 6 mmol). The mixture was stirred at RT for 14 h. An aqueous solution of NaHCO3 was added and the mixture was extracted three times with methylene chloride. The combined organic layers were washed with brine and dried over MgSO4. The solvent was removed by evaporation and the product was purified by reversed phase chromatography (C8) using acetonitrile and aqueous ammonium acetate solution (0.1 M) as eluent. There was obtained 0.20 g (59%) of 1-[1-(diphenylmethyl)azetidin-3-yl]-N,N-dimethylpiperidine-4-carboxamide. 1H NMR (500 MHz, CDCl3): δ 1.6-2.0 (cm, 6H), 2.4-2.5 (m, 1H), 2.8 (m, 2H), 2.9-3.0 (m, 5H), 3.1 (s, 3H), 3.4 (t, 2H), 4.4 (s, 1H), 7.2 (t, 2H), 7.3 (t, 4H), 7.4 (d, 4H); LCMS: m/z 378 (M+1)+.
