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Paper | Regular issue | Vol 29, No. 2, 1989, pp.339-348
Published online, 1st January, 1970
DOI: 10.3987/COM-89-4748
Rearrangements of Arylhydrazones of N-Acylbenzimidazoles - Synthesis of 2-Aryl-1,2,4-triazolo[4,3-a]quinoxalinium Salts

Giuseppe Cusmano and Gabriella Macaluso

*Dipartimento Chimica Organica, Università digli Studi di Palermo, Viale delle Scienze, 90128 Palermo, Italy


The acid induced rearrangement of arylhydrazones of N-acylbenzimidazoles has been investigated. An initial 6π heteroelectrocyclic reaction involving the hydrazone side chain and the imidazole moiety, followed by a ring opening gave 4-(2-aminopheny1)-1,2,4-triazolium perchlorate 7 as intermediates. The latter species, depending on the substituent present in the triazole moiety, gave the 2-aryl-1,2,4-triazolo[4,3-a]quinoxalinium perchlorates 8 or 9 as the final rearranged products. Alkaline cleavage of the triazolo[4,3-a]quinoxalinium perchlorates 8 and 9 to 3-(arylformylhydrazino)guinoxaline derivatives 11 and 13 has been pointed out.