5.6- Diphenyl-1,2,4-triazine 4-oxide

Diphenyl-1,2,4-triazine 4-oxide 139 was obtained by reaction of diphenyl-glyoxal mono-2-ethoxymethylenehydrazone 140 with hydroxylamine. The reaction proceeds via formation of an isonitroso intermediate, followed by cyclization to the 1,2,4-triazine 4-oxide 139 (71LA12). 

Hsynthesis from, 3, 767 Indenobenzazepines pharmacological properties, 7, 546 Indenone oxide, 2,3-diphenyl-photochromic compound, 1, 385 In deno[ 1,2-c][ 1,2,4]triazines synthesis, 3, 434 Indicated hydrogen nomenclature, 1, 33 Indigo, I, 317, 318-319, 4, 370 Baeyer synthesis, 1, 319 colour and constitution, 1, 344-345 molecular structure, 4, 162 photochromic compound, 1, 386 synthesis, 4, 247 Indigoid dyes... 

The reaction of 3,6-diphenyl-1,2,4-triazine 4-oxide 58 with benzoylacetone under basic conditions affords substituted 1,2,4-triazine 74 in low yield (96MC116). 

Electrochemical reduction of various 3,4-disubstituted-l,2,5-thiadiazole 1,1-dioxides (3,4-diphenyl- 10, phenanthro[9,10]- 51, and acenaphtho[l,2]- 53) gave the corresponding thiadiazoline 1,1-dioxides <1999CJC511>. Voltammetric and bulk electrolysis electroreduction of 3,4-diphenyl-l,2,5-thiadiazole 1-oxide 9 at ca. —1.5 V, in acetonitrile, gave 3,4-diphenyl-l,2,5-thiadiazole 8 (50%) and 2,4,6-triphenyl-l,3,5-triazine 54 (30%) (Equation 3) <2000TL3531>. 

Azidomethylbenzenediazonium tetrafluoroborate, 2708 Benzenediazonium tetrafluoroborate, 2223 2-Chloro-3-pyridinediazonium tetrafluoroborate, 1816 5-(4-Diazoniobenzenesulfonamido)thiazole tetrafluoroborate, 3119 5,6-Diphenyl-l,2,4-triazine-3-diazonium tetrafluoroborate 2-oxide, 3677... 

Diphenyl-1,2,4-triazine-3-diazonium tetralluoroborate 2-oxide, 3677 Ethyl 4-diazo-l,2,3-triazole-5-carboxylate, 1853 l-Ethyl-l,l,3,3-tetramethyltetrazenium tetralluoroborate, 2586 Formylhydrazine, 0473... 

Data on the structures of monocyclic dihydro- or hexahydro-1,2,3-triazines, on 1,2,3-triazine tV-oxides and 1,2,3-triazinones are not yet available. From studies on the one-electron reduction of the tetrahydro-l,2,3-triazinium salts (7) it was concluded that the heterocyclic ring is flexible and not planar (80LA285). No detailed information on the structure of 3-benzyl-l,5-diphenyl-l,2-dihydro-l,2,3-triazine-4,6(3//,5f/)-dione (8) or of the 6-hydroxy-4-oxo-l,4-dihydro-l,2,3-triazinium hydroxide inner salts (9) seems to be available. 

Diphenyl-1,2,4-triazine-3-diazonium tetrafluoroborate 2-oxide, 3670 f Diphosphane, 4533... 

In the 1,3,5-triazine series the oxidative amination of diphenyl-1,3,5-triazine into aminodiphenyl-1,3,5-triazine has been reported (Scheme 29) (82JHC1285). 

When the dihydro-1,2,4-triazinone (194) is heated at 180 °C under reducing conditions there is rupture of the 1,2-bond followed by ring closure, producing 4,5-diphenyl-imidazolinone (195). Such reductive ring closures of benzotriazine 1-oxides (196) can give benzimidazoles, in particular 2-(4-thiazolyl)benzimidazoles (197) ( thiabendazole ). Similar reactions take place with 1,3,5-triazines. In fact, primary amines cleave the compounds completely with evolution of ammonia and formation of iV.iV -disubstituted formamidines. With suitable primary amines, though, this reaction can be designed to produce imidazolines or benzimidazoles (Scheme 113). 

Sion of carbon monoxide. Thus 5,6-diphenyl-l,2,4-triazine-3(2H)-one (1) is converted into 4,5-diphenyltriazolc (2) in 94% yield. Chloramine is thus acting as an oxidant, probably with initial N-chlorination. 

---