Regioselective formation of 1,2,4-triazoles by the reaction of amidrazones in the presence of diethyl azodicarboxylate and catalyzed by triethylamine
- 178 Downloads
A general method for the synthesis of 1,3,5-trisubstituted 1,2,4-triazoles has been developed from reaction of amidrazones with ethyl azodicarboxylate and triethylamine (Mitsunobu reagent) in EtOH. This highly regioselective one-pot process provides rapid access to highly diverse triazoles. The reaction was explained, based on Mitsunobu reagent oxidizing ethanol to acetaldehyde, which would then react with amidrazones to give the substituted 3-methyltriazoles. A [2 + 3] cycloaddition reaction between two oxidized forms of amidrazones produced the second type of triazoles. X-ray structure analyses proved the structure of each type of product.
KeywordsAmidrazones Mitsunobu reagent Regioselective 1,2,4-Triazoles
The authors thank 3-MET Society, Karlsruhe Institute of Technology, Karlsruhe, Germany, for financial support to Prof Ashraf A. Aly enabling him to carry out analyses in the aforesaid Institute. Purchase of the NMR spectrometer at Florida Institute of Technology was assisted by the US National Science Foundation (CHE 03-42251).
- 4.Turan-Zitouni G, Kaplancikli ZA, Yildiz MT, Chevallet P, Kaya D (2005) Synthesis and antimicrobial activity of 4-phenyl/cyclohexyl-5-(1-phenoxyethyl)-3-[N-(2-thiazolyl)acetamido]thio-4H-1,2,4-triazole derivatives. Eur J Med Chem 40:607–613. https://doi.org/10.1016/j.ejmech.2005.01.007 Google Scholar
- 7.Almasirad A, Tabatabai SA, Faizi M, Kebriaeezadeh A, Mehrabi N, Dalvandi A, Shafiee A (2004) Synthesis and anticonvulsant activity of new 2-substituted-5-[2-(2-fluorophenoxy)phenyl]-1,3,4- oxadiazoles and 1,2,4-triazoles. Bioorg Med Chem Lett 14:6057–6059. https://doi.org/10.1016/j.bmcl.2004.09.072 Google Scholar
- 12.Aly AA, Ramadan M, Abd El-Aziz M, Bräse S, Brown AB, Fathy HM, Nieger M (2017) Regioselective synthesis of 5-aminopyrazoles from reactions of amidrazones with activated nitriles: NMR investigation and x-ray structural analysis. Chem Pap 71:1409–1417. https://doi.org/10.1007/s11696-017-0131-x Google Scholar
- 36.Mangarao N, Mahaboob Basha G, Ramu T, Srinuvasarao R, Prasanthi S, Siddaiah V (2014) Brønsted acid-catalyzed simple and efficient synthesis of 1,2,4-triazoles and 1,2,4-oxadiazoles using 2,2,2-trichloroethyl imidates in PEG. Tetrahedron Lett 55:177–179. https://doi.org/10.1016/j.tetlet.2013.10.147 Google Scholar