Reaction Steps
H2O2 (70%, 0.63 mL, ca. 12.7 mmol) was added dropwise to a stirred solution of TFM (1.8 mL, 12.7 mmol) in DCM (15 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 36 (397 mg, 1.3 mmol) and TFA (0.20 mL, 2.5 mmol) in DCM (20 mL) at 0° C. The solution was stirred at 5° C. for 4 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 purified by chromatography, eluting with a gradient (0-10%) of MeOH/DCM, to give 1,4-dioxide 37 (241 mg, 57%) as a red solid: mp (MeOH/EtOAc) 165-168° C.; 1H NMR δ 8.11 (s, 1H, H-9), 8.08 (s, 1H, H-5), 7.43 (br s, 1H, NH), 3.60-3.64 (m, 2H, CH2N), 3.03-3.11 (m, 4H, H-6, H-8), 2.62 (t, J=6.0 Hz, 2H, CH2N), 2.42-2.47 (m, 4H, 2×CH2), 2.15-2.22 (m, 2H, H-7), 1.57-1.63 (m, 4H, 2×CH2), 1.41-1.47 (m, 2H, CH2); 13C NMR δ 155.6, 149.5, 145.7, 138.0, 129.7, 115.8, 111.6, 56.9, 54.4 (2), 38.2, 33.4, 32.4, 25.9 (2), 25.6, 24.3. Anal. calcd for C17H23N5O2.¼H2O: C, 61.2; H, 7.1; N, 21.0. Found: C, 60.7; H, 7.0; N, 21.0%.
