2- Substituted 1,2,3-triazole 1-oxides structure

No mass spectra of 1,2,3-triazoles were described prior to 1968, when a series of highly substituted triazoles, the oxidation products of 1,2-dicarbonyl-bis-benzoylhydrazones, were investigated. The previously assigned structure of a dihydro-1,2,3,4-tetrazine could be excluded in favor of the 1,2,3-triazole-isoimide (52), which showed a low intensity molecular ion Mt, but a prominent [M-28] ion corresponding to loss of N2 giving (53) (68TL231). The [Af-28] ion underwent further fragmentations as shown in Scheme 1. 

Since both oxepin and its valence isomer benzene oxide contain a x-tb-diene structure they are prone to Diels-Alder addition reactions. The dienophiles 4-phenyl- and 4-methyl-4//-l,2,4-triazole-3,5-dione react with substituted oxepins at room temperature to give the 1 1 adducts 7 formed by addition to the diene structure of the respective benzene oxide.149 190,222... 

A number of 2H-1,2,3-triazole 1-oxides 72 were prepared by chemists at the Cassella Company as potential NO-donors in view of their formal structural similarity with furoxan derivatives [18]. Derivative 72a was studied in depth. It was obtained by cupric sulfate oxidation of intermediate 79, derived from the action of the substituted phenylhydrazine 78 on the oximino acetoacetic acid amide 77 (Scheme 6.13). 

The aromatic 2-substituted 1,2,3-triazole 1-oxides are represented by the structure 341. The parent compound 342 is one of the three possible tautomeric forms of 1-hydroxy-l,2,3-triazole 343. 1-Hydroxy-l,2,3-triazoles 343 constitute a separate group of compounds, which are not included in the present review (Scheme 101). 

The resonance structures of the 2-substituted 1,2,3-triazole 1-oxides 341 are discussed in Section 1.1.1. According to IUPAC nomenclature, structure 341 is a 2-substituted 2H-l,2,3-triazole 1-oxide. Other names found in the literature are 2-substituted 1,2,3-triazole 1-oxides. In the present review the most commonly used naming, which is accepted by IUPAC, Chem. Abstr. Autonom., has been adopted calling structure 341 a 2-substituted 1,2,3-triazole 1-oxide. 

Monocyclic 2-substituted 1,2,4-triazole 1-oxides derived from 522 have been reported (Scheme 153). The structure of the /V-oxide fragment was proved by X-ray crystallography (2010LOCEC377). IR, H NMR, C NMR, and MS data have been published (1976JCS(P1)2166). 2-Substituted... 

The 1-substituted 1,2,4-triazole 4-oxides with the basic structure 532 are hygroscopic. They form hydrates, which lose the water by heating to melting or by recrystallization from anhydrous solvents. 1,2,4-Triazole 4-oxides 534 are 4 p/< , units weaker as a base than their deoxygenated progenitor 533 (1972JPR101). 

B enzyne and Cyclobutadlene Stereoelectronlc Activation - The catalytic interaction of cytochrome P-450 with 1-aminobenzotriazole (2), a compound that releases benzyne when chemically oxidized, results in time-dependent enzyme inactivation. 2,63 An unusual prosthetic heme adduct is formed in which two vicinal nitrogens of protoporphyrin IX are bridged by an ortho-substituted phenyl ring. The Inactivation reaction occurs even when substituents are placed on the exocyclic amino group of 1-amlnobenzo-triazole, although enzyme inactivation by substituted analogues has not been well characterized. The catalytic role of the enzyme and the structure of the heme adduct indicate that inactivation follows oxidative release of benzyne or a benzyne-like species within the active site of the enzyme. 

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