A Multicomponent Coupling Sequence for Direct Access to Substituted Quinolines

A titanium-catalyzed three-component coupling reaction can be used to generate tautomers of N-aryl-1,3-diimines. Simple treatment of these products with acetic acid leads to cyclization forming quinoline derivatives in a one-pot procedure. The primary amines employed can be substituted anilines, aminonaphthalenes, or even heterocyclic amines, which leads to a variety of fused-ring heterocyclic frameworks. The one-pot yields varied from 25-71% for the 18 examples presented in this study.