Intramolecular Cyclization of Peri-Substituted 1-Azidonaphthalenes. 3. Structural and Chemical Investigation of 1-(Arylamino)benzindazol-8(and -6)(1H)-ones Produced by Decomposition of Hydroxy-Substituted 8-Azido-1-(arylazo)naphthalenes

Article abstract of DOI:10.1021/jo00132a004

Thermal and photochemical decomposition of 8-azido-2-hydroxy-1-(arylazo)naphthalenes 3a-d leads to 1-(arylamino)benzindazol-8(1H)-ones 4a-d in good yields.Analogous results are obtained in the conversion of 5 into 6.The reactions appear to proceed through 1,5-cyclization of the tautomeric hydrazone forms of the azides, and the absence of products that would be expected from nitrene intermediates suggests that the reactions proceed through a concerted mechanism.Evidence is presented to support the benzindazolone structures rather than the isomeric triazines.The ratios of O- and N-alkyl derivatives obtained on alkylation of 4a-d depend on the type of substituent in the arylamino ring and on the bulk of the alkyl group.