To a stirred solution at room temperature of VIII (140 mg, 0.68 mmol) in anhydrous DMF (5 ml) under nitrogen were added Et3N (104 μl, 0.75 mmol) and BOP reagent (331 mg, 0.75 mmol), respectively. After 30 min, a solution of 3-(aminomethyl)pyridine (90 μl, 0.88 mmol) or R1R2NH (1.2–1.3 equiv.), Et3N (284 μl, 2.04 mmol) in anhydrous DMF (2 ml) was added dropwise. After 4 h, the reaction mixture was poured into a saturated aqueous solution of NH4Cl, and diluted with AcOEt. After separation, the organic layer was successively washed with sat NH4Cl, H2O and brine, dried over MgSO4, filtered, and concentrated. The crude residue was then purified by flash chromatography on silica gel (MeOH/CH2Cl2:5/95→7/93) to afford the title compound IXb (185 mg, 0.62 mmol, 92% yield) as a white solid. 1H NMR (300 MHz, CDCl3) δ(ppm): 8.67–8.44 (m, 2H), AB system (δA=8.03, δB=7.55, J=8.4 Hz, 4H), 7.78–7.64 (m, 2H), 7.33–7.26 (m, 1H), 6.54 (d, J=15.8 Hz, 1H), 6.38 (bs, 1H), 4.61 (d, J=6.2 Hz, 2H), 3.92 (s, 3H).
