PPh3-Mediated cascade reaction of 2-alkynylnitrobenzenes and 1,2-diaminoarenes for the construction of 2-aryl-3-(2-aminoaryl)quinoxalines

Abstract

A simple method for the preparation of 2-aryl-3-(2-aminoaryl)quinoxalines from 2-alkynylnitrobenzenes and 1,2-diaminoarenes was described. The reactions could proceed under mild conditions. The 1-nitro-2-(phenylethynyl)benzenes, simple starting materials, could generate the key intermediate 3H-indole-3-ones in situ in the presence of PPh₃. After a cyclization with 1,2-diaminobenzenes, the 3H-indole-3-ones were then transformed into biologically valuable quinoxalines.