Various readily available, Ugi-derived dehydroalanines were used as pivotal templates to easily and efficiently assemble diverse pharmacologically important polyheterocyclic systems through cascade palladium-catalyzed C–C bond formation processes. Allyl, homoallyl and propargylamine led to the formation of benzopyrrolizidinones, benzoindolizidinones and pyrazinoisoquinolines, respectively, while benzylamines and o-bromobenzylamines were used as precursors of tetracyclic-fused systems and pyrazionoisoquinolindiones.