80% |
With 3-chloro-benzenecarboperoxoic acid; In dichloromethane; at 0℃; for 16h;Inert atmosphere; |
Quinoxaline (295 mg, 1.71 mmol) was added in a two-necked flask (10 mL) equipped with a stirring bar. Under nitrogen atmosphere, dry and degas CH2Cl2 (3 mL) was added. At 0C, a solution of m-chloroperbenzoic acid (150 mg, 1.15 mmol in 3 mL of CH2Cl2) was added dropwise at the reaction mixture. After 16 hours, NaHCO3 solution was added and extracted with CH2Cl2 (3 x 10 mL). The organic phase was dried with MgSO4 and the solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel (ethyl acetate/methanol 8:1) to obtain white crystals (199 mg, 80%), m.p.: 122 - 123C, 1H NMR (300 MHz, CDCl3) delta = 8.68 (d, J = 3.5 Hz, 1H), 8.59 (dd, J = 8.5, 1.3 Hz, 1H), 8.36 (d, J = 3.5 Hz, 1H), 8.14 (dd, J = 8.3, 1.0 Hz, 1H), 7.84 (ddd, J = 8.4, 7.0, 1.6 Hz, 1H), 7.76 (ddd, J = 8.4, 7.0, 1.4 Hz, 1H). 13C NMR (101 MHz, CDCl3) delta = 145.4, 145.3, 137.8, 132.2, 130.6, 129.7, 129.6, 119.1. |
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With sodium hydrogencarbonate; 3-chloro-benzenecarboperoxoic acid; In dichloromethane; at 0 - 40℃; for 0.25 - 6h; |
Formation of Quinoline-N-oxides: The appropriate quinoline (10 mmol) may be dissolved in CH2Cl2 and treated with solid NaHCO3 (50 mmol) followed by m-CPBA (10.0 mmol). The reaction may be stirred at between 0-40C for between 15 minutes to 6 hours. In one variation, the reaction is stirred at about 23 C for 4 hours. The mixture may then be transferred to a separatory funnel and washed with water, saturated aqueous NaHCO3 and brine, and then dried (MgS04) and concentrated in vacuo. The resulting crude solid is often pure enough to carry forward to the next reaction. |