Preparation method of favipiravir and derivatives thereof
A technology of derivatives and compounds, which is applied in the field of new preparation of Favipiravir and its derivatives, can solve the problems of cumbersome operation, unfriendly environment, and many reaction steps, and achieve simple operation, environmental friendliness, and high total yield Effect
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Embodiment 1
[0022] Add 13.9 g of 3-hydroxypyrazine-2-carboxamide to 100 ml of DMF, then add 60 g of Selectfluor, raise the temperature to 70-80°C, react for 12 hours, and cool down to 0-5°C. Filter out the unreacted raw material, distill off most of the solvent under reduced pressure, add 100 ml of water, 50 ml of methanol, stir for 1 hour, filter, collect the solid, obtain after drying under reduced pressure at 50-60 ° C, 11 g of light yellow solid (HPLC 99.2%, yield 70%), the nuclear magnetic spectrum of this light yellow solid is as figure 2 Shown, determine that it is Favipiravir, as shown in reaction formula (1) B:
[0023]
Embodiment 2
[0025] Add 13.9 g of 3-hydroxypyrazine-2-carboxamide to 100 ml of DMF, then add 63 g of NSFI, raise the temperature to 70-80°C, react for 12 hours, and cool down to 0-5°C. The unreacted raw material was filtered off, most of the solvent was distilled off under reduced pressure, 100 ml of water and 50 ml of methanol were added, stirred for 1 hour, filtered, and the solid was collected, dried under reduced pressure at 50-60°C to obtain 10.2 g of light yellow solid (HPLC99. 3%, yield 65%), the nuclear magnetic spectrum of this light yellow solid is the same as embodiment 1, confirms that it is Favipiravir, as shown in reaction formula (2) B:
[0026]
Embodiment 3
[0028] Add 13.9 g of 3-hydroxypyrazine-2-carboxamide to 100 ml of dichloroethane, then add 60 g of Selectfluor, heat up to 70-80°C, react for 24 hours, cool down to 0-5°C, add 100 ml of ethyl acetate ester. The unreacted raw materials were filtered off, most of the solvent was distilled off under reduced pressure, 100 ml of water and 50 ml of methanol were added, stirred for 1 hour, filtered, and the solid was collected, dried under reduced pressure at 50-60°C to obtain 10.67 g of light yellow solid (HPLC 99.4 %, yield 68%), the nuclear magnetic spectrum of this light yellow solid is the same as embodiment 1, confirms that it is Favipiravir, as shown in reaction formula (3) B:
[0029]
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