Several new and synthetically useful approaches involving palladium catalysis and electrophilic cyclization have been described for the synthesis of potentially medicinally and industrially important heterocycles and carbocycles. The methods used are quite general and have been utilized to synthesize a wide variety of important heterocyclic and carbocyclic ring systems including isochromenes, cyclic imidates, as well as linear and fused polyheterocyclic compounds (PHCs) containing benzofurans, benzothiophenes, indoles, and isocoumarin subunits.