Sequential annulation of bidentate diamines for modular access to N-fused/helical/spiro-carbazole scaffolds

Abstract

Cu-catalysed mono N-annulation of bidentate diamines with cyclic diaryliodonium salts has been disclosed to build N-aminoaryl carbazoles with good yields, high selectivity, and narrow FWHMs. The resultant N-aminoaryl carbazoles can easily transform into N-fused/helical/spiro-carbazole scaffolds through diazotization of the residual NH₂ followed by intramolecular electrophilic cyclization. The type and size of the second ring are tailored by the distance of two NH₂ groups in diamines. Furthermore, the UV-vis and fluorescence spectra and quantum yields of the novel scaffolds are characterized, and their promising photophysical outputs make them potential building blocks for future OLED emitters.