Synthesis of quinoline derivatives using ketene dithioacetals

Abstract

AbstractMethyl 3‐(N‐arylamino)‐2‐cyano‐3‐methylthioacrylates 3a‐h, which are readily prepared by the reaction of the ketene dithioacetal, methyl 2‐cyano‐3,3‐bis(methylthio)acrylate (1) with arylamines, was heated at reflux in diphenyl ether to give the corresponding 2‐methylthio‐4‐hydroxyquinoline‐3‐carbonitriles 4a‐h in 14–77% yields. The reaction of 1 with excess aryl amines in diphenyl ether at reflux gave also the corresponding 2‐arylamino‐4‐hydroxyquinoline‐3‐carbonitriles 6a‐d. The 2‐methylthioquinoline‐3‐carbonitriles 4a‐h, thus obtained, are useful intermediates for the synthesis of various quinoline derivatives.