Direct synthesis of aryl-annulated [c]carbazoles by gold(i)-catalysed cascade reaction of azide-diynes and arenesElectronic supplementary information (ESI) available: Experimental details and spectral data are provided. CCDC 1860899 and 1860900 (6aF-Me2), 1860901 and 1860902 (7aF-Me2), and 1860904 and 1860905 (11A-Me2). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8sc03525c

The gold-catalysed annulation of conjugated alkynes bearing an azido group with arenes gave annulated [ c ]carbazoles. Using benzene, pyrrole, and indole derivatives as the nucleophiles, benzo[ c ]-, pyrrolo[2,3- c ]-, and indolo[2,3- c ]carbazoles were produced, respectively. The reaction proceeded through pyrrole and benzene ring construction accompanied by the formation of two carbon-carbon and one carbon-nitrogen bond and the cleavage of two aromatic C-H bonds. The mechanism of the reaction with pyrrole was investigated by density functional theory calculations. N , N ′-dimethylated indolo[2,3- c ]carbazole showed dual ultraviolet-visible-near-infrared and fluorescence spectral changes upon electrolysis. The gold-catalysed annulation of conjugated alkynes bearing an azido group with arenes gave annulated [ c ]carbazoles.