trans-[4-(2-oxo-ethyl)-cyclohexyl]-carbamic acid tert-butyl ester [CAS-Nr. 215790-29-7] (1.0 g, 4 mmol) was added to a solution under N2 of commercially available 4-piperazine-1-yl-thieno[3,2-c]pyridine [CAS-Nr. 106261-27-2] (0.85 g, 4 mmol) in 1,2-dichloroethane (45 ml) and AcOH (0.22 ml, 4 mmol). The resulting reaction mixture was stirred 8 h at room temperature before addition of Na(AcO)3BH (1.2 g, 6 mmol). Stirring was continued over night at room temperature. Sat. aq. NaHCO3 sol. was added and the product was extracted with EtOAc (2×). The combined organic layers were washed with H2O and brine. After drying (MgSO4) the solvent was evaporated and the product was purified by flash chromatography on silica gel (CH2Cl2/MeOH, 100:0 to 90:10) to yield trans-{4-[2-(4-thieno[3,2-c]pyridin-4-yl-piperazin-1-yl)-ethyl]-cyclohexyl}-carbamic acid tert-butyl ester as a light yellow solid (1.2 g, 72%), MS (ISP) m/z=445.3 [(M+H)+].
