- A SIMPLE PROCESS FOR THE PREPARATION OF FAVIPIRAVIR AND ITS INTERMEDIATES THEREOF
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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.
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Page/Page column 8
(2022/01/04)
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- Scalable synthesis of favipiravir: Via conventional and continuous flow chemistry
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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
- Charoensetakul, Netnapa,Khamkhenshorngphanuch, Thitiphong,Srikun, Onsiri,Srimongkolpithak, Nitipol,Thongpanchang, Chawanee,Tiyasakulchai, Thanat,Yuthavong, Yongyuth
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p. 38691 - 38693
(2021/12/20)
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- Fapiravir and preparation method of intermediate thereof
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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.
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Paragraph 0048-0053; 0068-0070
(2020/12/08)
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- METHOD FOR PRODUCING DICHLOROPYRAZINE DERIVATIVE
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A method for producing a hydroxypyrazine derivative represented by formula (I) (wherein R1 represents a halogen atom), the method including reacting a pyrazine derivative represented by formula (III) (wherein R2 represents a nitrile group, an N-unsubstituted or N-substituted carbamoyl group, an ester group or a carboxyl group, M represents a cation capable of forming a salt, and n represents a number corresponding with the valence of M) with a halogenating agent. Also, a method for producing a dichloropyrazine derivative represented by formula (II) (wherein R21 represents a nitrile group, an N-unsubstituted or N-substituted carbamoyl group, an ester group, a carboxyl group, or a group formed as a result of a change in the functional group of R2 during chlorination), the method including reacting the hydroxypyrazine derivative (I) with a chlorinating agent. According to the present invention, a dichloropyrazine derivative can be produced efficiently at low cost, and a hydroxypyrazine derivative that functions as a production intermediate for the dichloropyrazine derivative can be produced efficiently at low cost.
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Page/Page column 4-5
(2011/11/13)
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