Reaction Steps
H2O2 (ca. 70%, 3.0 mL, 59.2 mmol) was added dropwise to a stirred solution of trifluoroacetic anhydride (8.4 mL, 59.2 mmol) in DCM (50 mL) at 5° C. The solution was stirred at 5° C. for 5 min, warmed to 20° C. for 10 min, then cooled to 5° C. and added to a stirred solution of 1-oxide 4 (1.48 g, 5.1 mmol) and trifluoroacetic acid (2.2 mL, 28.0 mmol) in CHCl3 (20 mL) at 5° C. The solution was stirred at 5° C. for 16 h, diluted with dilute aqueous NH3 solution (10 mL) and extracted with CHCl3 (4×50 mL). The combined organic fraction was dried and the solvent evaporated. The residue was chromatographed, eluting with a gradient (0-10%) of MeOH/DCM, to give 1,4-dioxide 5 (529 mg, 32%) as a red solid, mp (MeOH/EtOAc) 155-158° C.; 1H NMR δ 8.54 (brs, 1 H, NH), 8.19 (d, J=9.0 Hz, 1 H, H-8), 8.08 (brs, 1 H, H-5), 7.38 (dd, J=9.0, 1.5 Hz, 1 H, H-7), 3.82-3.85 (m, 4 H, 2×CH2O), 3.66-3.70 (m, 2 H, CH2N), 2.55-2.59 (m, 5 H, CH2N, CH3), 2.49-2.54 (m, 4 H, 2×CH2N), 1.85-191 (m, 2 H, CH2); 13C NMR δ 150.0, 147.9, 138.3, 129.1, 128.7, 121.4, 116.1, 66.9 (2), 57.8, 53.9 (2), 41.7, 24.7, 22.3. Anal. Calcd for C15H21N5O3¼CH3OH: C, 56.0; H, 6.8; N, 21.4. Found: C, 55.9; H, 6.7; N, 21.0%.
