A mixture in DMF (1 ml) of trans-4-[2-(4-thieno[2,3-c]pyridin-7-yl-piperazin-1-yl)-ethyl]-cyclohexylamine trihydrochloride (intermediate A; 90 mg, 0.20 mmol), propionic acid (15 mg, 0.20), iPr2NEt (103 mg, 0.80 mmol) and TBTU (67 mg, 0.21 mmol) was stirred 18 h at room temperature. Sat. aq. NaHCO3 sol. was added and the product was extracted with EtOAc (3×). The organic layers were washed with water and brine, dried (MgSO4) and the solvent was evaporated. The crude product was purified by flash chromatography on silica gel (CH2Cl2/MeOH 95:5) to yield the title compound as an off-white crystalline solid (66 mg, 83%), MS (ISP) m/z=401.3 [(M+H)+].
