To a stirred solution of the product of Step A (0.436 g, 2 mmol) in anhydrous CH2Cl2 (10 ml) and Et3N (0.3 ml) mesyl chloride (0.4 ml) was added at 0° C. and stirring was continued for 1 h. The solvents were evaporated to dryness under reduced pressure and the residue was diluted to 50 ml with EtOAc and washed with H2O. The organic layer was separated and dried over MgSO4 and filtered. The filtrate was evaporated to give the crude product (0.63 g) as pale paste, which was taken up in anhydrous toluene and 4-fluoro-N-isopropylaniline (0.5 ml) was added to it. The mixture was stirred overnight at reflux and the solvent was evaporated. The residue was purified by FCC(SiO2, hexane/EtOAc) to give the title compound (0.14 g, 20%), as light creamy paste. 1H-NMR (CDCl3) 9.98 (s, 1H,); 7.82 (d, 2H, J=8.31 Hz); 7.66 (d, 2H, J=8.31 Hz); 7.28 (d, 1H, J=3.69 Hz); 6.93-6.86 (m, 3H); 6.81-6.76 (m, 2H); 4.79 (s, 2H); 4.08-3.99 (m, 1H); 1.22 (d, 6H, J=6.6 Hz).
