23429-04-1Relevant articles and documents
Method for preparing oxazole carboxylic acid ester
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Paragraph 0054-0098, (2021/09/04)
The invention relates to the technical field of organic synthesis of medicines, and discloses a method for preparing oxazole carboxylic acid ester. The method provided by the invention comprises the following steps: in the presence of a catalyst, a dehydrating agent and organic alkali, carrying out cyclization reaction on a compound as shown in a formula (II) to obtain a compound as shown in a formula (I), the catalyst is an imidazole compound; wherein in the formula (I) and the formula (II), R1, R2 and R3 are respectively and independently C1-C6 alkyl groups. According to the method, the imidazole compound is used as the catalyst for preparing the oxazole carboxylic ester, so that the reaction yield can be remarkably improved. In addition, the method provided by the invention is simple in process, does not involve the use of other auxiliaries, does not generate phosphorus-containing wastewater, belongs to a green process, and is beneficial to industrial production.
Synthesis method of ethyl 4-methyl-5-ethoxy-oxazole carboxylate
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Paragraph 0037-0056, (2019/12/02)
The invention discloses a synthetic method of ethyl 4-methyl-5-ethoxy-oxazole carboxylate. The method specifically comprises the following steps: mixing N-ethoxyoxalyl alanine ethyl ester with an organic solvent, cooling the mixture, adding a solution containing triphenylphosphine, iodine and alkali, then raising the temperature, continuing to carry out a reaction while maintaining the temperature, adding a quenching agent for terminating the reaction; and carrying out separation treatment to obtain the ethyl 4-methyl-5-ethoxy-oxazole carboxylate. According to the method, the triphenylphosphine, the iodine and the alkali are used as reaction reagents, so that the use of highly toxic products is reduced, the reaction conditions are mild, the reaction yield is high, no special requirement onequipment exists, the cost is low, and the yield is high.
Synthesis method of 4-methyl-5-ethyoxy oxazole
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Paragraph 0044; 0069; 0070, (2019/02/19)
The invention discloses a synthesis method of 4-methyl-5-ethyoxy oxazole. The synthesis method comprises the following steps: sequentially adding methylbenzene, N-ethoxyoxoacetyl alanine ethyl ester,triethylamine and phosphorus oxychloride, and heating for a cyclization reaction; adding water and liquid caustic soda into the product of the cyclization reaction; when the pH value shows alkalinity,performing a saponification reaction; after layering of the saponification reaction product, collecting the lower-layer reactant; adding an aqueous solution of hydrochloric acid into the lower-layerreactant till acidity, and heating for reacting, wherein the lower-layer reactant sequentially experiences acidification and decarboxylation to obtain a product solution generating 4-methyl-5-ethoxy oxazole; neutralizing the product solution with alkali till neutrality, and performing separation and purification to obtain 4-methyl-5-ethoxy oxazole. According to the synthesis method disclosed by the invention, the synthesis technology of 4-methyl-5-ethoxy oxazole is optimized, and the wastewater generated in the technological process is reduced.