Practical and Simple Synthesis of Substituted Quinolines by an HCl−DMSO System on a Large Scale: Remarkable Effect of the Chloride Ion

[reaction: see text] A variety of substituted quinolines are synthesized from imines and enolizable carbonyl compounds under aerobic conditions, in which only water is a byproduct. In DMSO, a catalytic amount of HCl activates carbonyl compounds quite effectively to give the quinolines. A simple and practical procedure is demonstrated on a large scale.