反应详情

H2O2 (70%, 0.72 mL, ca. 14.3 mmol) was added dropwise to a stirred solution of TFAA (2.0 mL, 14.3 mmol) in DCM (20 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. and added to a stirred solution of 1-oxide 98 (490 mg, 1.4 mmol) and TFA (0.55 mL, 7.1 mmol) in DCM (20 mL) at 0° C. The solution was stirred at 20° C. for 6 h, diluted with dilute aqueous NH3 solution (10 mL) and extracted with CHCl3 (4×30 mL). The combined organic fraction was dried and the solvent evaporated. The residue was purified by chromatography, eluting with a gradient (0-10%) of MeOH/DCM, to give (i) starting material 98 (280 mg, 57%) and (ii) 1,4-dioxide 99 (88 mg, 17%) as a red solid: mp (MeOH/DCM) 161-163 DC; 1H NMR δ 8.30 (br s, 1H, NH), 8.08 (br s, 2H, H-5, H-9), 3.82 (br t, J=4.5 Hz, 4H, 2×CH2O), 3.58-3.63 (m, 2H, CH2N), 3.15-3.25 (m, 2H, CH2), 2.61-2.74 (m, 3H, CH, CH2), 2.57 (br t, J=6.1 Hz, 2H, CH2N), 2.47-2.53 (m, 4H, 2×CH2N), 1.83-1.90 (m, 2H, CH2), 1.18 (d, J=6.2 Hz, 3H, CH3); 13C NMR δ 155.2, 149.5, 145.2, 138.1, 129.5, 115.8, 111.7, 66.9 (2), 57.7, 53.8 (2), 41.6, 41.4, 40.4, 34.9, 24.5, 20.2. Anal. calcd for C18H25N5O3: C, 60.2; H, 7.0; N, 19.5. Found: C, 60.6; H, 7.0; N, 18.3%.