226986-41-0Relevant academic research and scientific papers
Formation of 1-phenyl-4-oxo [1,2,4]triazolo[4,3-a]quinoxaline from 2- chloro-3-(2'-benzylidenehydrazino)quinoxaline during dehydrogenative cyclisation using cupric acetate
Krishnan,Chowdary,Dubey
, p. 1371 - 1373 (2007/10/03)
Attempted dehydrogenative cyclisation of 2-chloro-3-(2'- benzylidinchydrazino)quinoxaline 5 with a view to prepare 1-phenyl-4-chloro- [1,2,4]-triazolo [4, 3-a]quinoxaline 6 using cupric acetate gives 1-phenyl-4- oxo-[1,2,4]triazolo[4,3-a]quinoxaline 7. A rational explanation is offered for this reaction and the applicability of cupric acetate as dehydrogenative cyclisation agent (such as in the conversion of 10→11) has been demonstrated.
Studies in the syntheses of s-triazolo[4,3-a] quinoxalines
Krishnan,Chowdary,Dubey
, p. 45 - 51 (2007/10/03)
o-Phenylendiamine 1 is condensed with oxalic acid using Phillip's procedure to obtain quinoxaline-2,3-doine 2, which on treatment with POCl3 gives the known 2,3-dichloroquinoxaline 3. 2-Chloro-3-hydrazinoquinoxaline 4 is prepared in a facile and simple way by treatment of 3 with hydrazine hydrate in methanol or in dioxane containing triethylamine. Condensation of 4 with a variety of aldehydes in DMF at room temperature furnishes the corresponding arylidene/alkylidine derivatives 5 which undergo smooth nucleophilic substitutions of chlorine by alkoxide or phenoxide ions yielding 2-alkoxy/phenoxy-3-(2-arylidene/alkylidene hydrazino) quinoxalines 6. The dehydrogenative cyclisation of 6 is achieved with chloranil in refluxing 1,2- dichloroethane resulting in s-triazole-[4,3-a] quinoxalines 7 whose structures are supported by spectral and analytical data and by alternate chemical synthesis in the case of the parent compound 7a.
