Visible-Light-Induced Regio-selective Oxidative Coupling of Quinoxalinones with Pyrrole Derivatives

Herein, one feasible methodology has been developed for oxidative cross-coupling between quinoxalinones and electron-rich aromatic rings (pyrroles or indoles). Utilizing the commerial available photocatalyst 4Mes-Acr-Me+ClO4- (3 mol%) as catalyst and air as external oxidant, the oxidative coupling products of quinolones and pyrrole derivatives were obtained in high yields. The protocol provides effective acceess to such quinoxalinones- pyrrole derivatives with profiles of broad functional group, efficient conversion and easy-handling. Furthermore, Stern-Volmer fluorescent quenching experiments under the same condition disclosed that quenching rate constant of electron-rich aromatic ring (pyrrole or indole, k(q) 1.06x10(10)similar to 1.07x10(10) L center dot mol(-1)center dot s(-1)) was nearly one order of magnitude larger than that of electro-deficient quinoxalinones (k(q)=1.2x10(9) L center dot mol(-1)center dot s(-1)).

Automated summary

A feasible methodology for oxidative cross-coupling between quinoxalinones and electron-rich aromatic rings (pyrroles or indoles) has been developed. By using the commercially available photocatalyst 4Mes-Acr-Me+ClO4- (3 mol%) as catalyst and air as external oxidant, the oxidative coupling products of quinolones and pyrrole derivatives were obtained with high yields. The protocol provides effective access to versatile quinoxalinones-pyrrole derivatives with broad functional group tolerance, efficient conversion, and easy handling. Fluorescent quenching experiments demonstrated that the quenching rate constant of electron-rich aromatic rings was nearly one order of magnitude larger than that of electron-deficient quinoxalinones.