1.2.4- Triazolo quinoxalines

The transformations of bis(triazole)-fused benzothiadiazepine 40 (Scheme 4) on treatment with -BuLi depended on the reaction temperature at —40°C, the sulfur extrusion occurred to afford fully aromatized bis(triazolo)quinoxaline 41, whereas at — 80°C, a seven-membered ring opening took place with formation of bis(triazolyl)benzene 42 <2002MC131>. 

Benzylidenehydrazino-3-methoxyquinoxaline (273) underwent oxidative cyclization to 4-methoxy-l-phenyl[l,2,4]triazolo[4,3-fl]quinoxaline (274) [Cu(OAc)2, AcOH, reflux, 1 h 80% " tetrachlorobenzoquinone, CICH2CH2 Cl, reflux, 90 min 92% " analogs by both procedures]... 

Chloro-2-[l-methyl-4-phenyl(thiosemicarbazido)]quinoxaline (275) gave 7-chloro-3-methyl[ 1,2,4]triazolo[4,3-fl]quinoxalin-3-ium-1 -thiolate (276) (Me2... 

Hydroxyimino)methyl]amino-3-methylquinoxahne (193) (considered here as the oxime of an aldehyde) gave 4-methyl[l,2,4]triazolo[l,5-u]quinoxaline (194) (polyphosphoric acid, 75°C, 7 h 66%). ... 

Reaction of 2,3-dichloroquinoxaline 367 with sodium azide in ethanol has been used to synthesize bistetrazolo-[l,5- 5, l -c]quinoxaline 368 in 65% yield (Scheme 28) <1997JOC4082>. Similarly, reaction of 2,3-dichloroquinoxaline 367 with thiosemicarbazide 366 has been used to generate l,6-diamino-bis-l,2,4-triazolo[4,3- 3,4-f]quinoxaline 365 in 67% yield <2002AP389>. Condensation of cyclopropanecarboxylic acid hydrazide 369 meanwhile gives rise to the cyclopropyl-substituted tetracycle 370 in 93% yield in the presence of l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as base (Scheme 28) <2005JOC2878>. 

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