Owing to the wide spread applications of pyromellitic dianhydride (PMDA) in several fields, such as synthesis of polyimides, epoxy resins and metal carboxylate complexes. These encourage us to synthesize new derivatives of condensed dipyrrole, dibenzoxazine and dipyridazine starting with pyromellitic dianhydride which may posses a greater certain pharmacological activity. This book, therefore, provides new chemical methods for the preparation of new heterocyclic compounds with a discussion of their chemical analysis and a detailed survey of the chemistry of pyromellitic dianhydride. This book is useful to professionals in organic chemistry and will help the chemistry students.