- Improved synthesis method of 6-methyl-2-ethyl-3-hydroxypyridine
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The invention discloses an improved synthesis method of 6-methyl-2-ethyl-3-hydroxypyridine, and belongs to the technical field of synthesis of medical intermediates. The method comprises the following steps: 1) reacting propionic anhydride with 2-methyl furan in the presence of a catalyst, washing with water after the reaction is finished, and performing reduced pressure distillation to obtain 5-methyl2-propionyl furan; and 2) mixing the 5-methyl-2-propionyl furan, ammonia water and p-toluenesulfonic acid, carrying out heating reaction, acidifying to be neutral, filtering to obtain a 6-methyl-2-ethyl-3-hydroxypyridine crude product, and recrystallizing to obtain a 6-methyl-2-ethyl-3-hydroxypyridine refined product. The raw materials are easy to obtain, common Lewis acid is added in the step (1), the reaction time is greatly shortened, the good yield is obtained, the acid aqueous solution obtained through washing in the step 1) is used for the acid adjusting process in the step 2), and the three-waste emission problem is basically solved; and 2) the reaction process is simple, a closed heating and pressurizing method is adopted, the raw materials react thoroughly, the yield is high, and the method is suitable for industrial production.
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Paragraph 0020; 0022; 0023; 0025; 0026; 0028
(2021/05/01)
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- Facile one-pot direct arylation and alkylation of nitropyridine N -oxides with grignard reagents
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Facile arylation and alkylation of nitropyridine N-oxides were developed through the reactions of Grignard reagents with nitropyridine N-oxides. For the same 4-nitropyridine N-oxide, arylation occurred at the 2- (or 6-) position, whereas alkylation occurred at the 3-position in an adjustably site-selective manner. The cooperative action of the two groups was discovered in the reactions of 3-nitropyridine N-oxides. This protocol can find wide applications in building various pyridine compounds as illustrated in total syntheses of Emoxipin and Caerulomycin A and E.
- Zhang, Fang,Duan, Xin-Fang
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p. 6102 - 6105
(2012/01/06)
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