356783-28-3Relevant articles and documents
PROCESS FOR THE PREPARATION OF 3,6-DICHLOROCYANO PYRAZINE, 3,6-DIOXOPIPERAZINE DERIVATIVES AND PRODUCTION OF FAVIPIRAVIR THEREOF
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, (2021/12/31)
The present invention relates to a method of preparing derivatives of 3,6-dichlorocyano pyrazine, 3,6-dioxopiperizin and the production of favipiravir by cyclization and chlorination mediated by ammonia or amine using POCl3 in the presence of pyridine or PCl5. [Formula] In derivatives of 3,6-dioxopiperazine (III), X represents CN, CONH2 or COOR2', R1, R 2 and R2' are individually selected from H, alkyl C1-C12, COOR3 and SO2R3, R 3 being a linear or branched lower alkyl substituted or unsubstituted.
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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, (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.
