反应详情

H2O2 (70%, 1.6 mL, ca. 33 mmol) was added dropwise to a stirred solution of TFAA (4.6 mL, 33 mmol) in DCM (30 mL) at 0° C. The solution was stirred at 0° C. for 5 min, warmed to 20° C. for 10 min, then cooled to 0° C. The solution was added to a solution of 1-oxide 70 (0.86 g, 3.3 mmol) in DCM (50 mL) at 0° C. and the solution was stirred at 20° C. for 16 h. Dilute aqueous NH3 solution (30 mL) was added and the mixture stirred vigorously for 30 min and then extracted with DCM (4×50 mL). The combined organic fraction was dried and the solvent evaporated. The residue was purified by chromatography, eluting with a gradient (0-5%) of MeOH/DCM, to give (i) starting material 70 (283 mg, 33%) and (ii) 1,4-dioxide 71 (347 mg, 40%) as a yellow solid: mp (MeOH/EtOAc) 153-155° C.; 1H NMR δ 8.33 (s, 1H, H-9), 8.26 (s, 1H, H-5), 3.68 (br dt, J=6.1, 5.7 Hz, 2H, CH2O), 3.33 (t, J=6.9 Hz, 2H, CH2), 3.13-3.20 (m, 4H, H-6, H-8), 3.09 (br t, J=6.1 Hz, 1H, OH), 2.26 (p, J=7.5 Hz, 2H, H-7), 2.10-2.18 (m, 2H, CH2); 13C NMR δ 155.5, 155.0, 150.9, 138.8, 134.0, 115.8, 114.1, 61.2, 33.4, 32.9, 29.6, 26.8, 25.6. Anal. calcd for C13H15N3O3: C, 59.8; H, 5.8; N, 16.1. Found: C, 60.0; H, 5.7; N, 16.1%.