Potassium Carbonate → 4-(3-Pyridin-4-yl-[1,2,4]oxadiazol-5-ylmethyl)piperazine-1-carboxylic acid tert-butyl ester

Methanesulfonic acid 3-pyridin-4-yl-[1,2,4]oxadiazol-5-ylmethyl ester (Preparation 12, 56 mg, 0.22 mmol) and potassium carbonate (30 mg, 0.22 mmol) were added to a solution of piperazine-1-carboxylic acid tert-butyl ester (37 mg, 0.2 mmol) in acetonitrile (4 ml). The stirred mixture was heated under reflux for 18 h, the solvent removed and the residue dissolved in EtOAc-water (90:10, 50 ml). The organic phase was separated, washed with brine, dried (MgSO4) and the solvent removed to give a residue which was purified by flash chromatography (IH-EtOAc, 4:1), affording the title compound: RT=3.26 min; m/z (ES+)=346.1 [M+H]+.