Novel route to 3(5)-fluoro-1,2,4-triazoles and 8-fluoropurines by displacement of the nitro group

Abstract

Ring-fluorinated 1,2,4-triazoles have not been previously reported and our interest in 1,2,4-triazoles has prompted us to investigate this class of heterocycles. Conventional synthetic routes to fluoro compounds arc notoriously unreliable when applied to new problems. Consequently, a number of novel methods2 of solvents. Recently the conversion of 3(5)-nitro-1,2,4-triazoles to the corresponding halo derivatives on treatment with halogen acids has been reported.4 The

Fluorinated Triazoles and Tetrazoles

“…The fi rst report on the preparation of 1,2,4-triazoles fl uorinated at the carbon atom of the ring appeared as early as 1973 [ 31 ]. In this study the corresponding 3-fl uoro-1,2,4-triazoles 20 were obtained in good yields by treatment of 5-R-3-nitro-1,2,4-triazoles 19 with hydrogen fl uoride.…”

Fluorinated Five‐Membered Nitrogen‐Containing Heterocycles

“…151 Reaction of 3(5)-nitrotriazoles with liquid HF at 150 C produces the corresponding 3(5)-fluoro-1,2,4-triazole in good yield (Fig. 3.83).…”

“…Sulfetrazone (151) and calfentrazone ethyl (152), briefly discussed above, are examples of azoles with a carbon-bearing fluorine directly attached to the ring nitrogen, a class of compound that has relatively received little attention. The reaction of five-membered aromatic heterocycles with tetrafluoroethylene and chlorotrifluoroethylene produced early examples of such compounds, including N-tetrafluoroethylpyrrole formed by the reaction of the potassium salt of pyrrole with tetrafluoroethylene.…”

The First Versatile Synthesis of 1-Alkyl-3-fluoro-1H-[1,2,4]triazoles

“…In our laboratory the need occurred for [1,2,4]triazoles bearing a fluoro substituent in the 3-or 5-position. They are useful as building blocks for the synthesis of biologically active compounds with modified electronic properties compared to unfluorinated [1,2,4]triazoles. The synthesis of 3(5)-fluoro- [1,2,4]triazoles has been achieved in three different ways.…”

“…They are useful as building blocks for the synthesis of biologically active compounds with modified electronic properties compared to unfluorinated [1,2,4]triazoles. The synthesis of 3(5)-fluoro- [1,2,4]triazoles has been achieved in three different ways. [1][2][3] 3(5)-Nitro- [1,2,4]triazoles were converted into 3(5)-fluoro- [1,2,4]triazoles by treatment with pure hydrogen fluoride at 150°C.…”