An Overview: The biologically important quninoline derivatives

Heterocyclic compounds are widely prevalent in animal kingdom as well as in plant kingdom and they play various roles in metabolic processes. A large number of heterocyclic compounds are in clinical practice as a drug, while many of them find industrial utility and hence the syntheses of heterocyclic compounds and understanding of the biological importance of specific heterocyclic class will be an interesting field of synthetic organic chemists. Introduction: In recent years, there has been a growing interest pertaining to the synthesis of bioactive compounds in the field of organic chemistry. A cyclic organic compound containing at least one atom other than carbon is designated as heterocycles. Nitrogen, oxygen and sulphur are the most common hetero atoms but heterocyclic rings with other hetero atoms also widely known. A large number of heterocyclic compounds are essential to life. Various compounds such as alkaloids, antibiotic, essential amino acids, vitamins, haemoglobin, hormones and a large number of drugs and dyes contain heterocyclic ring systems. Living organisms, particularly mankind were highly depending on bio-active molecules to treat various diseases. Presently, tremendous research is in progress to develop the drug molecules; usually these molecules were derived or isolated either from natural (biological) sources or through the synthesis. Due the extraordinary context of disease reducing properties of heterocycles, they were prescribed for various types of treatment. The significance of the heterocycles in the drug industry was also revealed by the recent survey in US which showed that more than 90 % of drugs sold recently in the US market were reported to have at least one heterocycle in it. The presence of oxygen, sulfur and nitrogen as hetero atoms increasing the hydrogen bond forming ability of heterocycle with the protein targets was the uniqueness of the heterocycle. Heterocycles also have greater chelating property, so that they bind to the metal ions and block certain process like metal poisoning (toxicity) or enzyme action. Quinoline derivatives: One of the important classes of heterocyclic chemistry is quinolone chemistry. The heterocyclic compound quinoline is Benzo[b]pyridine. Generally quinoline derivatives are synthesized by Skraup’s, Doebener-Miller’s and Friedlander’s synthesis. Quinolines are weakly basic (pKa = 4.94) and placed in between aniline (pKa = 4.58) and pyridine (pKa = 5.17). The pyridine ring in quinoline is electron deficient therefore nucleophilic attack takes place at second and fourth positions and the electrophilic attack takes place at fifth and eighth positions. International Journal of ChemTech Research CODEN (USA): IJCRGG ISSN: 0974-4290 Vol.9, No.03 pp 629-634, 2016 V. Vijayakumar /International Journal of ChemTech Research, 2016,9(3),pp 629-634. 630