One-step synthesis of favipiravir from Selectfluor® and 3-hydroxy-2-pyrazinecarboxamide in an ionic liquid

Abstract

Favipiravir is an important selective antiviral that emerged as an alternative against COVID-19 during pandemic. Its synthesis has gained great interest and the conventional strategies proceed through multiple-step protocols (6-7...

Tautomerism and Rotamerism of Favipiravir and Halogenated Analogues in Solution and in the Solid State

“…Also, from the point of view of organic synthesis, the elucidation of the tautomerism and rotamerism of these types of pyrazines is an important issue for understanding the factors that govern the direct fluorination of 3-hydroxy-2-pyrazinecarboxamide 1e using Selectfluor. 63…”

“…This concept could play a role in the selective activity of this type of system as an RNA inhibitor, and its exact elucidation from a structural point of view is of great relevance for further interpretations. Also, from the point of view of organic synthesis, the elucidation of the tautomerism and rotamerism of these types of pyrazines is an important issue for understanding the factors that govern the direct fluorination of 3-hydroxy-2-pyrazinecarboxamide 1e using Selectfluor …”

Direct Synthesis of 8‐Fluorocaffeine and Its Transformation to 8‐Substituted Caffeine

“…The mechanism of fluorination using Selectfluor®-mediated is possible through single-electron transfer (SET) pathways. [22,37] Apart from using Selectfluor®, fluorination of caffeine was attempted using Synfluor in acetonitrile at 100 °C for 4 hours, in the reflux condition, however, the 8-fluorocaffeine (1) could not be formed.…”

Photoproperties of favipiravir and its 6-substituted analogues: fluorescence controlled through halogen substitution and tautomerism

“…The 3-methoxy analogue 3a was prepared previously by our group. 13 Absorption data were obtained from a Thermo Scientific Varioskan Flash Multimode instrument for air-equilibrated solutions at 25 °C. Lifetimes and photostability were measured in a ChronosFD Fluorescence Lifetime Spectrometer (ISS, Champaign, IL, USA).…”

“…This property has been useful for its quantification in plasma through spectrofluorometric measurements 10 and for monitoring the chemical synthesis of favipiravir. 13 Other reports have demonstrated the ability of favipiravir to induce the appearance of fluorescence in human hair and nails after favipiravir administration. 14 Some theoretical analyses based on DFT calculations have provided an approximation of the absorption and emission spectra of favipiravir and 6-substituted analogues (Cl, Br, I, H and CH 3 ).…”