Synthesis of biologically interesting heteropolicyclic systems by palladium-catalyzed processes

Palladium-catalyzed processes provide an efficient strategy for functionalization of arenes and heteroarenes with C-C and C-N bond formation and continue to offer new applications to obtain a wide range of polyfunctionalized compounds such as fused heteropolicyclic systems. The indole nucleus is the focus of the research interests but also other heterocycles such as pyrrole, furan and thiophene are examined and functionalized. The palladium complexes exist in different oxidation states showing different reactivity. Pd(0)-complexes exhibit nucleophilic behaviour while Pd(II)-complexes react as electrophiles, thus different complexes are involved in different reaction typologies. The present thesis exploits the formation of new carbon-carbon and carbon-nitrogen bonds by using, among the known Pd-catalyzed reactions, Heck reaction, Buchwald-Hartwig reaction, oxidative coupling and amination reactions. All these reactions proceed under relative mild reaction conditions and tolerate a wide variety of functional groups, thus avoiding protection group chemistry. Besides, some reaction typologies offer the possibility to use substrates without prefunctionalized C-X bonds (X = halogens, OTf, etc.) for the construction of complex structures, often poly-heterocyclic systems, as well as the possibility to attain the aim in few steps, and this goal is of considerable importance and not easily obtainable by other methods.