Fe-catalyzed cycloaddition of indoles and o-phthalaldehyde for the synthesis of benzo[b]carbazoles with TMSCl- or acid-responsive properties

Abstract

The one-pot iron-catalyzed cycloaddition of indole and o-phthalaldehyde afforded indolyl benzo[b]carbazoles via sequential carbon–carbon bond-forming addition, cyclization involving intramolecular alkylation and aromatization forming a benzene ring. In addition, the fluorescence properties of such indolyl benzo[b]carbazoles were investigated, in which significant changes in fluorescent intensity were observed upon the addition of trimethylchlorosilane (TMSCl) or trifluoroacetic acid (TFA).