To a solution of 7-(piperazin-1-yl)-2,3-dihydro-furo[2,3-c]pyridine (0.96 g, 4.68 mmol) in dichloromethane (30 ml) and MeOH (0.8 ml) was added at room temperature commercially available trans-tert-butyl-4-(2-oxoethyl)-cyclohexylcarbamate (1.71 mg, 6.02 mmol) and triethylamine (1.02 g, 1.4 ml, 10 mmol) and the solution was allowed to stir for 30 min. Sodium triacetoxyboron hydride (1.91 g, 9.03 mmol) was added step wise and the mixture was allowed to stir for 4 h at room temperature. The solution was added to ice/2N sodium carbonate solution (50 ml), extracted with dichloromethane (2×30 ml). The combined organic layers were dried (MgSO4) and evaporated. The crude material (2.53 g) was purified by flash chromatography on silica gel (20% to 100% dichloromethane/dichloromethane-MeOH 9:1) to yield trans-(4-{2-[4-(2,3-dihydro-furo[2,3-c]pyridin-7-yl)-piperazin-1-yl]-ethyl}-cyclohexyl)-carbamic acid tert-butyl ester as off-white solid (1.3 g, 65%), MS (ISP) m/z=431.5 [(M+H)+], mp 141° C.
