Construction of 3,3'-Bicarbazoles and Indolocarbazoles by Using Visible Light

Abstract

A synthetic and mechanistic study of novel iterative double cyclization intramolecular SRN1 reactions from diarylamines bearing two aryl halide moieties was carried out. This cyclization affords symmetric and unsymmetric 3,3'-bicarbazoles and indolocarbazoles compounds in regular to very good yields. The synthetic strategy employed for their preparation was a Buchwald-Hartwig arylation of anilines followed by an intramolecular SRN1 reaction, in the presence of base and visible light, at room temperature. The mechanism is non-trivial and it was studied using spectroscopy and computational calculations, employing the DFT method, with B3LYP and M06-2X functionals and 6-31+G*, def2SVP and def2TZVP as bases and radicals are proposed as intermediates.