To a solution of benzooxazole-2-ylamine (35.8 mg, 0.267 mmol) in CH2Cl2 (6.0 mL) was added N,N′-disuccinimidyl carbonate (68.4 mg, 0.267 mmol). The reaction mixture was stirred at rt for 6 h, then treated with 1-[3-(4-chloro-phenoxy)-benzyl]-piperazine hydrochloride (100 mg, 0.267 mmol) and diisopropylethylamine (92 μL, 0.536 mmol) and stirred for an additional 16 h at rt. The reaction mixture was diluted with EtOAc (100 mL) and extracted with H2O (100 mL) then saturated aqueous NaCl (50 mL). The organic layer was dried (MgSO4), and concentrated. The crude residue was purified (FCC, 2 N NH3 in MeOH/DCM) to give 4-[3-(4-chloro-phenoxy)-benzyl]-piperazine-1-carboxylic acid benzooxazol-2-ylamide (78.0 mg, 63%). MS (ESI+): calcd for C25H23ClN4O3 m/z 462.15, found 463.5 (M+H)+. 1H NMR (d6-DMSO): 12.13 (br s, 1H), 7.46-7.39 (m, 3H), 7.36 (t, J=7.9, 1H), 7.30 (br s, 1H), 7.22 (t, J=7.6, 1H), 7.18-7.11 (m, 2H), 7.04 (d, J=9.0, 2H), 7.00 (br s, 1H), 6.94-6.91 (m, 1H), 3.73-3.54 (br m, 4H), 3.50 (s, 2H), 2.40-2.31 (m, 4H).
