Book Overview

1.1: General Introduction The chemistry of heterocyclic compounds containing nitrogen has expanded exponentially in the past decades due to their unique physical properties, specific chemical reactivity and their remarkable potential biological activities1. A survey of literature on the nitrogen heterocycles reveals that triazole, pyrazole, pyrimidine etc. are important constituents of wide variety of materials with pharmacodynamic applications2. The heterocyclic systems with seven atoms, once considered chemical oddities, are today just as easily obtained as five and six membered analogues, and these compounds no longer remain the esoteric species, they were once considered to be. Quite to the contrary, the pace of research and development in this area is accelerating due to the substantial advances that have been made in the synthesis of these materials in the last few decades. As a result of this there is virtually no limit to the number of interesting ring systems that can be created in the laboratory today by the combination of ingenuity and perseverance3. The ubiquity of benzazepines in chemical literature is undoubtedly a consequence of the multifarious biological response which they elicit in combating a variety of body ailments. The use of this class of compound is not merely confined to the management of stress related conditions and for their use as antibacterial agents 19, 20, but their additional novel applications are continously emerging. A perusal of literature on benzazepine derivatives reveal that the broad spectrum of biological properties 13 associated with these molecules has triggered the development of a variety of methods for the synthesis of these material and has led to an impressive armoury of synthetic strategies to be devised in the literature 13,15 for their synthesis. Many analogues have been synthesized in which benzene ring has been replaced by a heterocyclic moiety and for these the synthetic methods often closely resemble those used for benzazepines themselves. Recently, attention has concentrated on compounds having an additional heterocyclic ring fused to the seven membered ring of benzazepine nucleus. In a quest to develop easily accessible routes to the synthesis of some novel heteroring annulated benzazepine derivatives, the present investigation aimed to examine the operational feasibility of the proposed strategies for the synthesis of wide range of compounds shown in [Schemes 1.55-1.56]. In recent days, active research has been initiated on halogen containing heterocycles particularly fluorine containing heterocycles 4. It has been found that introduction of fluorine atom into an organic molecule largely enhances the pharmacological properties as compared to the non-fluorinated analogues. The incorporation of fluorine has been reported to increase the lipid solubility thereby enhancing the rate of absorption and transport of drug in vivo. Though, fluorine has greater size than hydrogen, several studies have demonstrated that fluorine is a reasonable hydrogen mimic which exerts only a minor steric demand at receptor sites. This observation stimulated us to undertake the synthesis of compounds shown in [Schemes 1.55-.156] containing the fluorine atom in their molecules. Chapter-I Introduction 7