Palladium-catalyzed tandem N–H/C–H arylation: regioselective synthesis of N-heterocycle-fused phenanthridines as versatile blue-emitting luminophores
作者:Lipeng Yan、Dongbing Zhao、Jingbo Lan、Yangyang Cheng、Qiang Guo、Xiaoyu Li、Ningjie Wu、Jingsong You
DOI:10.1039/c3ob41760c
日期:——
A general and highly regioselective synthetic protocol for structurally diverse N-heteroaryl-fused phenanthridines has been developed. Varieties of fluorescence molecules comprising imidazole-fused, benzoimidazole-fused, indole-fused and pyrrole-fused phenanthridines were obtained by this modular approach, some of which exhibit excellent blue-emitting performance, high quantum yields, long fluorescence lifetimes, interesting electrochemical properties, and thermal stabilities.
Starting from 2-arylbenzimidazoles and aryl halides, an efficient palladium-based catalytic method for the synthesis of benzimidazole-fused phenanthridines has been developed. This reaction sequence comprises intermolecular C-H arylation and intramolecular aerobic oxidative C-H amination, involving the rupture of two C-H bonds, one C-X bond, and one N-H bond in one pot. The Pd-II-Pd-IV-Pd-II and Pd-II-Pd-0-Pd-II catalytic cycles work together under the reported conditions to generate phenanthridines with diverse substituents.