Rationally designed conjugated microporous polymers for efficient photocatalytic chemical transformations of isocyanides

Abstract

Due to the versatile synthetic utility of isocyanides, great efforts have been made to develop metal-free, mild and effective catalytic systems for chemical transformations of isocyanides. In this work, a photocatalytical N–H insertion like reaction of isocyanides promoted by click-based conjugated microporous polymers (CMPs) is reported for the first time. We prepared three 1,2,3-triazole-based CMPs (Ta-Ths) via click reactions of 1,3,5-triethynylbenzene with 2,5-bis(4-azidophenyl)thiophene, 2-(3-azidophenyl)-5-(4-azidophenyl)thiophene and 2,5-bis(3-azidophenyl)thiophene, respectively. The polymers with distinct photoelectronic properties are obtained to effectively catalyze the visible light-driven N–H insertion like reaction between amines and isocyanides. In contrast, the S–H insertion of thiols with isocyanides was not detected at all under similar reaction conditions, instead thiocarbamates were obtained. As a heterogeneous photocatalyst, the polymer has also shown good reusability after recycling five times without a significant activity loss.