Efficient Synthesis of Substituted Indoles and Benzazoles by Oxidative Aromatization Using Activated Carbon-Molecular Oxygen System

Efficient synthesis of substituted indoles was achieved by oxidative aromatization of indolines using activated carbon-molecular oxygen (O 2 ) system.Benzazoles (benzimidazole and benzothiazoles) were also prepared by the reaction of 1,2-phenylenediamine and 2-aminobenzenethiol with formaldehyde in the presence of activated carbon under oxygen atmosphere.The indole moiety occurs naturally in a variety of structures. 1 There are many synthetic methods for indole framework.Fischer indole synthesis 2 is one of the most classical and established methods.Other than Fischer indole synthesis, Reissert synthesis, 3 Gassman synthesis, 4 Bartoli synthesis, 5 Madelung synthesis, 6 Nenitzescu synthesis, 7 Larock synthesis 8 and their modified methods have been reported.All