In recent years many specialised works on specific topics in heterocyclic chemistry have appeared, while at the same time the more general text-books on organic chemistry have not given this important part of the subject the attention it deserves. In fact, the chemistry of heterocycles lies at the heart of drug discovery. During the last few decades, a considerable attention has been devoted to synthesis of heterocyclic Compounds and their derivatives possessing such comprehensive bioactivities as antimicrobial, anti inflammatory, analgesic, antitumorial, antihypertensive, anti convalsant,...