Intermediate 28 (490 mg, 1.32 mmol), N-Benzylpiprazine (280 mg, 1.6 mmol), K2CO3 (190 mg, 1.4 mmol), CuCl (6.5 mg, 0.05 mmol), acetyl acetone (17 mg, 0.12 mmol) were dissolved in NMP (2 ml). This reaction mixture was stirred at 130° C. for 15 h under N2 atmosphere. Work up (EtOAc/H2O) followed by column purification on 60-120 mesh silica gel using a gradient mixture of EtOAc and Petether (1:1) as eluent afforded 5-(4-benzylpiperazin-1-yl)-2-[2-fluoro-4-(methylsulfonyl)phenyl]benzo[d]oxazole (250 mg) as a yellow solid. 5-(4-Benzylpiperazin-1-yl)-2-[2-fluoro-4-(methylsulfonyl)phenyl]benzo[d]oxazole (130 mg, 0.28 mmol) dissolved in DCM (15 ml) and added isopropylchloro formate (102 mg, 0.84 mmol). This mixture was stirred at reflux for 18 h. Work up (DCM/H2O) followed by purification of the crude by column chromatography on 230-400 mesh silica gel using a gradient mixture of EtOAc and Petether (30:70) as eluent afforded the titled compound (25 mg) as a pale-yellow solid. M.P.: 231-234° C. 1H-NMR (δ ppm, CDCl3, 400 MHz): 8.28 (d, J 8.7, 1H), 7.96 (d, J 1.6, 1H), 7.68-7.64 (m, 2H), 7.57-7.47 (m, 2H), 4.95 (septet, J 6.2, 1H), 3.71-3.63 (m, 4H), 3.12-3.06 (m, 4H), 1.26 (d, J 6.2, 6H).
