Synthesis of Structurally Diverse Benzotriazoles via Rapid Diazotization and Intramolecular Cyclization of 1,2-Aryldiamines

An operationally simple method has been developed for the preparation of N-unsubstituted benzotriazoles by diazotization and intramolecular cyclization of a wide range of 1,2-aryldiamines under mild conditions, using a polymer-supported nitrite reagent and p-tosic acid. The functional group tolerance of this approach was further demonstrated with effective activation and cyclization of N-alkyl, -aryl, and -acyl ortho-aminoanilines leading to the synthesis of N-1-substituted benzotriazoles. The synthetic utility of this one-pot heterocyclization process was exemplified with the preparation of a number of biologically and medicinally important benzotriazole scaffolds, including an alpha-amino acid analogue.