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.