反应详情

温度

-78 °C

70.0 ml (106 mmol) of n-butyllithium (1.5 mol/l hexane solution) was dropwise added at 0° C. to a diethyl ether 120 ml solution of 15.0 ml (107 mmol) of diisopropylamine, followed by stirring for 1 hour. The solution was cooled to −78° C., and a diethyl ether 10 ml solution of 22.1 g (102 mmol) of 2,3-dichloro-5-trifluoromethylpyridine was added, followed by stirring for 30 minutes to prepare 2,3-dichloro-5-trifluoromethyl-4-pyridyllithium, and then a toluene 40 ml solution of 21.0 g (100 mmol) of 2,3,4-trimethoxy-6-methylbenzaldehyde was added, followed by stirring for 2 hours. 30 ml of water was added to the mixture to terminate the reaction, and the aqueous layer was extracted with ethyl acetate. Then, the organic layer was dried over anhydrous sodium sulfate and subjected to filtration, and the solvent was distilled off under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 24.8 g (yield: 58%) of (2,3,4-trimethoxy-6-methylphenyl)(2,3-dichloro-5-trifluoromethyl-4-pyridyl)methanol (melting point 95 to 98° C.). (b) 2.1 g of 5% palladium carbon was added to a methanol 200 ml solution of 24.8 g (58.1 mmol) of (2,3,4-trimethoxy-6-methylphenyl)(2,3-dichloro-5-trifluoromethyl-4-pyridyl)methanol obtained in Step (a) and 9.50 ml (68.2 mmol) of triethylamine, followed by stirring under hydrogen atmosphere for 4 hours. The mixture was subjected to filtration, 50 ml of water was added, and methanol was distilled off under reduced pressure. The aqueous layer was extracted with ethyl acetate, and the organic layer was dried over anhydrous sodium sulfate and subjected to filtration, and the solvent was distilled off under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 15.9 g (yield: 70%) of (2,3,4-trimethoxy-6-methylphenyl)(3-chloro-5-trifluoromethyl-4-pyridyl)methanol (melting point: 102 to 105° C.). (c) 45 g of manganese dioxide was added to a toluene 220 ml solution of 15.9 g (40.6 mmol) of (2,3,4-trimethoxy-6-methylphenyl)(3-chloro-5-trifluoromethyl-4-pyridyl)methanol obtained in Step (b), followed by stirring under reflux with heating for 2 hours. The mixture was subjected to filtration, and the solvent was distilled off under reduced pressure to obtain 14.9 g (yield: 94%) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-3-chloro-5-trifluoromethylpyridine. (d) 16.4 g (304 mmol) of sodium methoxide was added to a toluene 150 ml solution of 18.5 g (47.5 mmol) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-3-chloro-5-trifluoromethylpyridine obtained in Step (c) and 16.6 ml (95.4 mmol) of hexamethylphosphorous triamide, followed by stirring under reflux with heating for 30 minutes. Water was added to terminate the reaction, and the aqueous layer was extracted with ethyl acetate. Then, the organic layer was dried over anhydrous sodium sulfate and subjected to filtration, and the solvent was distilled off under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 11.7 g (yield: 64%) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-3-methoxy-5-trifluoromethylpyridine (melting point: 103 to 106° C.). (e) 6.1 g (28 mmol) of m-chloroperbenzoic acid (m-CPBA) was added at 0° C. to a chloroform 100 ml solution of 5.6 g (15 mmol) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-3-methoxy-5-trifluoromethylpyridine (Compound No. 122), followed by stirring at room temperature for 18 hours. The reaction solution was washed with a sodium hydroxide aqueous solution, and the solvent was distilled off under reduced pressure to obtain 5.8 g (yield: 99%) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-3-methoxy-5-trifluoromethylpyridine-N-oxide (melting point 128 to 134° C.). (f) 1.8 ml (19 mmol) of phosphorus oxychloride was added at 0° C. to 4 ml of toluene and 8 ml of dimethylformamide, followed by stirring for 10 minutes, and then 4.0 g (10 mmol) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-3-methoxy-5-trifluoromethylpyridine-N-oxide was added, followed by stirring for 20 minutes. After stirring at room temperature for 2 hours, the reaction solution was charged into ice water to terminate the reaction. The aqueous layer was extracted with ethyl acetate, and then the organic layer was dried over anhydrous sodium sulfate and subjected to filtration, and the solvent was distilled off under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 3.57 g (yield: 85%) of 4-(2,3,4-trimethoxy-6-methylbenzoyl)-2-chloro-3-trifluoromethyl-5-methoxypyridine (melting point 117 to 119° C.).

1. stirringby stirring for 30 minutes
2. stirringby stirring for 2 hours
3. customto terminate
4. customthe reaction
5. extractionthe aqueous layer was extracted with ethyl acetate
6. dry with materialThen, the organic layer was dried over anhydrous sodium sulfate
7. filtrationsubjected to filtration
8. distillationthe solvent was distilled off under reduced pressure
9. customThe crude product was purified by silica gel column chromatography