Reaction Steps
H2O2 (70%, 2.5 mL, ca. 50 mmol) was added dropwise to a stirred solution of TFM (7.1 mL, 50 mmol) in DCM (50 mL) at 0° C. The solution was stirred at 20° C. for 10 min, then cooled to 0° C., added to a solution of 1-oxide 32 (1.7 g, 5.0 mmol) and TFA (1.9 mL, 25 mmol) in DCM (50 mL) at 0° C. The solution was stirred at 20° C. for 6 h, diluted with dilute aqueous NH3 solution (80 mL) and extracted with DCM (4×125 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 1,4-dioxide 33 (620 mg, 35%) as a red solid: mp 129-131° C.; 1H NMR δ 8.13 (s, 1H, H-9), 8.10 (s, 1H, H-5), 7.39 (br s, 1H, NH), 3.57-3.66 (m, 2H, NCH2), 3.46 (t, J=6.3 Hz, 2H, OCH2), 3.33 (s, 3H, OCH3), 3.11 (dt, J=7.4, 0.9 Hz, 2H, H-8), 3.06 (dt, J=7.4, 1.1 Hz, 2H, H-6), 2.68 (t, J=6.0 Hz, 2H, NCH2), 2.52 (t, J=7.2 Hz, 2H, NCH2), 2.28 (s, 3H, NCH3), 2.20 (p, J=7.4 Hz, 2H, H-7), 1.77 (tt, J=7.2, 6.4 Hz, 2H, CH2); 13C NMR δ 155.6, 149.5, 145.7, 138.0, 129.7, 115.8, 111.6, 70.7, 58.6, 55.8, 54.3, 41.7, 38.8, 33.4, 32.4, 27.4, 25.6; MS (APCI) m/z 348 (MH+, 100%). Anal. calcd for C17H25N5O3: C, 58.8; H, 7.3; N, 20.2. Found: C, 58.8; H, 7.0; N, 20.0%.
