- Method for preparing 5-amino-1,2-dihydropyrazole-3-one from orotic acid
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The invention discloses a method for preparing 5-amino-1,2-dihydropyrazole-3-one from orotic acid, belonging to the field of drug intermediate synthesis. The method comprises the following steps: reacting orotic acid serving as a raw material with hydrazine hydrate to generate 5-oxygen-2,5-dihydropyrazole-3-carboxylic acid; reacting 5-oxygen-2,5-dihydropyrazole-3-carboxylic acid with diphenylphosphoryl azide by taking triethylamine as alkali to cause Curtis rearrangement, and carrying out hydrolysis, so as to generate 5-amino-1,2-dihydropyrazole-3-one. According the method, the cheap and easily available natural substances are taken as the raw materials, no strong base is utilized, and by-products are safe; meanwhile, the process selection is reasonable, the facility requirement is low, the operation is simple, the yield is high, the total yield can reach 83%, and the production is easily enlarged; the method is applicable to the large-scale production of 5-amino-1,2-dihydropyrazole-3-one.
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Paragraph 0028; 0029
(2016/11/21)
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