A Simple and Regioselective Preparation of 2- or 3-Substituted Quinoline Derivatives via Dialkylquinolylboranes

Various quinoline derivatives possessing a substituent at the 2-or 3-position were prepared by the reaction of dialkylquinolylboranes and organic bromides in the presence of a palladium catalyst.Since numerous quinolines occur in natural sources and have valuable chemotherapeutic, tumorinhibiting and fungicidal properties, much attention has been paid to the syntheses of substituted quinolines, but the general methods for regioselective introduction of an aryl, a heteroaryl, or an alkenyl group into quinoline nucleus are scarce.'We have previously reported a convenient procedure for the regioselective introduction of various substituents (i.e., aryl, heteroaryl, alkenyl) into the 3-or 4-position of pyridine by the palladium-catalyzed cross-coupling reaction between diethylpyridylboranes and organic halides.2We wish to report here a simple and regioselective preparation of 2-or 3-substituted quinoline de-3 revatives (1) from dialkylquinolylboranes (1) and organic bromides (1) in the presence of a palladium catalyst.