356783-16-9Relevant articles and documents
PROCESS FOR PREPARATION OF FAVIPIRAVIR
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Paragraph 0259, (2021/12/08)
The present invention relates to a process for the preparation of favipiravir and salts thereof. The present invention also relates to salts of 6-fluoro-3-hydroxy-2-pyrazinecarbonitrile with inorganic base, process for their preparation and conversion thereof to favipiravir. The present invention also relates to salts of 6-bromo-3-hydroxypyrazine-2-carboxamide with organic and inorganic base and their use in the preparation of favipiravir.
Scalable synthesis of favipiravir: Via conventional and continuous flow chemistry
Charoensetakul, Netnapa,Khamkhenshorngphanuch, Thitiphong,Srikun, Onsiri,Srimongkolpithak, Nitipol,Thongpanchang, Chawanee,Tiyasakulchai, Thanat,Yuthavong, Yongyuth
, p. 38691 - 38693 (2021/12/20)
Decagram scale synthesis of favipiravir was performed in 9 steps using diethyl malonate as cheap starting material. Hydrogenation and bromination steps were achieved by employing a continuous flow reactor. The synthetic process provided a total of 16% yield and it is suitable for larger-scale synthesis and production. This journal is
Favipiravir intermediate and synthesis method of favipiravir
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Paragraph 0060; 0061, (2020/08/12)
The invention discloses a favipiravir intermediate and a synthesis method of favipiravir. The synthesis method comprises the following steps: taking 2,5-dihalopyrazine as an initial raw material, reacting 2,5-dihalopyrazine with formamide under the action of an oxide and a catalyst to generate 6-halo-3-chloro-2-amide pyrazine; carrying out a reaction on 6-halo-3-chloro-2-amide pyrazine under the action of a dehydration chlorinating agent and an acid-binding agent to generate a favipiravir intermediate 3,6-dichloro-3-cyanopyrazine; carrying out an aromatic ring fluorination reaction on the obtained favipiravir intermediate and potassium fluoride in dimethyl sulfoxide to generate 3,6-difluoro-3-cyanopyrazine; adding the 3,6-difluoro-3-cyanopyrazine into a water solution containing sodium acetate, and carrying out hydrolysis to obtain 6-fluoro-3-hydroxyl-2-cyanopyrazine; and finally, carrying out a cyano hydrolysis reaction to obtain favipiravir. A mixture of 2,5-dichloropyrazine and 2-chloro-5-bromopyrazine are used as raw materials to synthesize the favipiravir intermediate, the raw material cost is remarkably reduced, and the provided synthesis method has the technical advantages of high yield and low cost.