First examples of palladium-catalyzed cross-coupling reactions, such as Suzuki, Sonogashira, Heck and Buchwald-Hartwig reactions, are reported in the pyrido[2,3-b]pyrazine series. This methodology circumvents problems found in uncatalyzed nucleophilic substitution used so far to introduce substituents into the pyrido[2,3-b]pyrazine ring.
palladium catalysis - cross-coupling - pyrido[2,3-b]pyrazine - heterocycles - synthesis