Heterocyclic Chemistry

Replacement and systematic nomenclature (Hantzsch-Widman system) for monocyclic, fused and bridged heterocycles.

Self Study: General chemical behaviour of aromatic heterocycles, classification (structural type), criteria of aromaticity (bond lengths, ring current and chemical shifts in 1H NMR-spectra, empirical resonance energy, delocalization energy and Dewar resonance energy, diamagnetic susceptibility exaltations), heteroaromatic reactivity and tautomerism in aromatic heterocycles.

Strain-bond angle and torsional strains and their consequences in small ring heterocycles. Conformation of six-membered heterocycles with reference to molecular geometry, barrier to ring inversion, pyramidal inversion and 1,3-diaxial interaction; stereo-electronic effects – anomeric and related effects; attractive interactions – hydrogen bonding and intermolecular nucleophilic-electrophilic interactions.

Three-membered and four membered heterocycles: synthesis and reactions of aziridines, oxiranes, thiiranes, azetidines, oxetanes and thietanes, five membered heterocycles: synthesis and reactions of different isomers of diazoles (pyrazoles, imidazoles), oxazoles, thiazoles, 1,2,4-triazole, oxadiazole, thiadiazole, 1,2,3,4-tetrazole.

Self study: synthesis and reactions of: pyrrole, triazole (1,2,3), tetrazole (1,2,3,5), isooxazole, isothiazole.

Synthesis and reactions including medicinal applications of benzopyrroles, benzofurans and benzothiophenes Meso-ionic heterocycles: classification, chemistry of some important meso-ionic heterocycles of type-A and B and their applications.

With one heteroatom: synthesis and reactions of pyrilium salts and pyrones and their comparison with pyridinium and thiopyrylium salts and pyridones; synthesis and reactions of quinolizinium and benzopyrylium salts, coumarins and chromones.

With two or more heteroatoms: synthesis and reactions of diazines, triazines, tetrazines and thiazines.