1237524-82-1Relevant articles and documents
A SIMPLE PROCESS FOR THE PREPARATION OF FAVIPIRAVIR AND ITS INTERMEDIATES THEREOF
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Page/Page column 8, (2022/01/04)
The present invention relates to a simple process for the preparation of Favipiravir of Formula (I). The present invention further relates to an improved process for the preparation of substantially pure 2-aminomalonamide of formula (II) a key starting material of Favipiravir.
Fapiravir and preparation method of intermediate thereof
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Paragraph 0048-0053; 0068-0070, (2020/12/08)
The invention relates to a fapiravir and a preparation method of an intermediate thereof, and belongs to the field of pharmaceutical chemicals. The invention provides a preparation method of a fapiravir intermediate 3-hydroxy sodium pyrazine-2-formamide, wherein the fapiravir intermediate 3-hydroxy sodium pyrazine-2-formamide is prepared by reacting aminopropanedioide with lithium chloride in thepresence of a NaOH solution and glyoxal. The invention also provides a preparation method of 6-bromo-3-hydroxy pyrazine-2-formamide, wherein the 6-bromo-3-hydroxy pyrazine-2-formamide is prepared froman acetonitrile solution of 3-hydroxy sodium pyrazine-2-formamide and an acetonitrile solution of liquid bromine in a microchannel reactor. The invention also provides a preparation method of 3, 6-difluoropyrazine-2-formamide, wherein the 3, 6-difluoropyrazine-2-formamide is prepared by reacting 6-bromo-3-hydroxy pyrazine-2-formamide with potassium bifluoride in the presence of PEG-400 and DMF. Finally, the invention also provides a total synthesis method for preparing fapiravir from the intermediate. The reactions avoid the use of highly dangerous diazotization reactions, and the methods have the advantages of high safety, low raw material price, short steps, low cost and simple post-treatment, and are suitable for industrial enlarged production.