Preparation method of 3-o-alkylation quinoxaline-2(1H)-ketone compound
A technology of ketone compounds and oxyalkylquinones, which is applied in the field of preparation of 3-oxoalkylquinoxalin-2-ones, can solve the problems of complex reaction steps, harsh reaction conditions, and long reaction time, and achieve The effect of saving reaction costs, mild reaction conditions, and simplifying post-processing steps
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Embodiment 1
[0030]
[0031] At 25°C, in a 15mL reaction tube, add 1-methylquinoxalin-2 (1H)-one 1a (0.2mmol), Rose Bengal (0.002mmol), triethylenediamine (0.2mmol), tert-butanol peroxide (0.2mmol), THF 2a (12 mmol, 1mL), mix well, and then stir the reaction for 24h under the irradiation of 3w blue LED light. After the reaction was detected by TLC, the reaction solution was concentrated to no solvent in vacuum (0.08Mpa) to obtain a crude product, which was washed with a mixed eluent of petroleum ether and ethyl acetate at a volume ratio of 3:1, Flash column chromatography on a silica gel column yielded 41.4 mg of the 1-methyl-3-(tetrahydrofuran-2-yl)quinoxalin-2(1H)-one product 3aa of this example as a colorless liquid with a yield of 90%.
[0032] The obtained product nuclear magnetic spectrum data are: 1 H NMR (CDCl 3 , 500 MHz, ppm): δ 7.81-7.78 (m,1H), 7.63-7.60 (m, 1H), 7.55 (t, J =8.3, 1H), 7.40-7.35 (m, 1H), 5.26-5.23 (m,1H), 4.04-4.00 (m, 1H), 3.87-3.83 (m, 1H), 3.61 (s, 3H...
Embodiment 2
[0035]
[0036] In a 15mL reaction tube, add 1,6,7-trimethylquinoxalin-2 (1H)-one 1b (0.2mmol), Rose Bengal (0.002mmol), triethylenediamine (0.2mmol), tert-butanol peroxide (0.2 mmol), THF 2a (12 mmol, 1 mL), mix well, then under the irradiation of 3w blue LED light, 20 ℃, stirring reaction for 24h. After detecting that the reaction is completed with TLC, the reaction solution is concentrated to solvent-free under vacuum (0.08Mpa) to obtain a crude product, which is then washed with a mixed eluent of petroleum ether and ethyl acetate with a volume ratio of 3:1, Flash column chromatography on a silica gel column yielded 37.1 mg of the 1,6,7-trimethyl-3-(tetrahydrofuran-2-yl)quinoxalin-2(1H)-one product 3ba in this example as a yellow oil. The rate is 72%.
[0037] The obtained product nuclear magnetic spectrum data are: 1 H NMR (CDCl 3 , 500 MHz, ppm): δ 7.56 (s, 1H),7.33 (s, 1H), 5.23-5.21 (m, 1H), 4.02-3.97 (m, 1H), 3.86-3.82 (m, 1H), 3.58(s, 3H), 2.37 ( s, 3H), 2.29...
Embodiment 3
[0040]
[0041] In a 15mL reaction tube, sequentially add 6-fluoro-1-methylquinoxalin-2 (1H)-one 1c (0.2mmol), water-soluble eosin (0.002mmol), triethylenediamine (0.2mmol), over Oxidized tert-butanol (0.2 mmol), THF 2a (12 mmol, 1 mL), mixed well, and then reacted with stirring at 60°C for 24 hours under the irradiation of a 3w blue LED light. After detecting that the reaction is completed by TLC, the reaction solution is concentrated to solvent-free under vacuum (0.08Mpa) to obtain a crude product, which is then washed with a mixed eluent of petroleum ether and ethyl acetate with a volume ratio of 3:1, Silica gel column flash column chromatography, the 6-fluoro-1-methyl-3-(tetrahydrofuran-2-yl)quinoxalin-2(1H)-one product 3ca of this example was obtained as a white solid 37.2 mg, yield 75%.
[0042] The obtained product nuclear magnetic spectrum data are: 1 H NMR (CDCl 3 , 500 MHz, ppm): δ 7.62-7.49 (m,3H), 5.25-5.22 (m, 1H), 4.05-4.01 (m, 1H), 3.89-3.84 (m, 1H), 3.6...
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