Studies in the syntheses of s-triazolo[4,3-a] quinoxalines

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 prep ared 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 subst itutions of chlorine by alkoxide or phenoxide ions yielding 2-alkoxylphenox y-3-(2-arylidene/alkylidene hydrazino) quinoxalines 6. The dehydrogenative cyclisation of 6 is achieved with chloranil in refluxing I,2-dichloroethane resulting in s-triazole-[4,3-a] quinoxalines 7 whose structures are suppor ted by spectral and analytical data and by alternate chemical synthesis in the case of the parent compound 7a.