Photoinduced Synthesis of Bisphosphinated Quinoxalines via Radical Cyclization of o‐Diisocyanoarenes with Diphosphines

A photoinduced synthesis of bisphosphinated quinoxalines was successfully achieved by using o-diisocyanoarenes with diphosphines. The novel reaction proceeds with good product selectivity, and can be conducted with easy operation, broad scope, and excellent atom-economy. Furthermore, this system can be applied to one-pot synthesis of Pd^II-quinoxaline complex.

Abstract

The cycloaddition reaction of o-diisocyanoarenes with interelement compounds under light is a very important reaction system to clarify whether this reaction proceeds by radical cyclization or by aza-Bergman cyclization. In this study, a series of diphosphines with phosphorus-phosphorus single bonds were selected as interelement compounds, and their cycloaddition reactions with o-diisocyanoarenes under light were investigated in detail to achieve a novel photoinduced synthesis of bisphosphinated quinoxalines via the radical cyclization pathway. In addition, the photoinduced reaction of diphosphines with isocyanides having o-functional groups such as cyano and ethenyl groups allowed us to elucidate the reaction pathway and product selectivity of this bisphosphination. Furthermore, the one-pot synthesis of Pd^II-quinoxaline complex was successfully achieved by applying the developed reaction.

Zum Volltext