RELATIVE STABILITIES OF HETARENIUM IONS - FACTORS CONTROLLING POSITIONAL SELECTIVITIES OF ELECTROPHILIC SUBSTITUTION AND ACID-INDUCED TRANSFORMATIONS OF PYRROLE, FURAN AND THIOPHENE DERIVATIVES

Positional selectivity in electrophilic substitution reactions of pyrr ole, thiophene and furan derivatives including methods of orientation control as well as stability and some transformations of hetarenium io ns are reviewed.