反应详情

H2O2 (70%, 0.35 mL, ca. 6.9 mmol) was added dropwise to a stirred solution of TFAA (1.0 mL, 6.9 mmol) in DCM (10 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 113 (188 mg, 0.7 mmol) and TFA (0.26 mL, 3.4 mmol) in DCM (10 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 113 (175 mg, 93%) and (ii) 1,4-dioxide 114 (8 mg, 4%) as a red gum: 1H NMR δ 8.11 (s, 1H, H-9), 8.08 (s, 1H, H-5), 6.98 (br s, 1H, NH), 3.63 (dq, J=7.2, 1.0 Hz, 2H, CH2N), 3.15-3.30 (m, 3H, CH, CH2), 2.95-3.07 (m, 2H, CH2), 2.33 [s, 6H, N(CH3)2], 1.36 (t, J=7.2 Hz, 3H, CH3); MS (FAB+) m/z 290 (MH+, 20%), 274 (5); HRMS (FAB+) calcd for C14H20N5O2 (MH+) m/z 290.1617, found 290.1607.