Heterocyclic Chemistry

Paper Code: 
CHY 423 C
Contact Hours: 

learn about synthetic organic chemistry and medicinal chemistry for research purposes

Unit I: 
Introduction and Nomenclature of Heterocycles

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.




Unit II: 
Conformational Analysis of Non-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.


Unit III: 
Small ring Heterocycles

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.

Unit IV: 
Benzo-Fused Five-Membered Heterocycles and Meso ionic

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.

Unit V: 
Six membered heterocycles

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.


Essential Readings: 
  1. Heterocyclic Chemistry Vol. 1-3; First Edition; R.R. Gupta, M. Kumar and V. Gupta; Springer Verlag, Berlin, Heidelberg, 1998.
  2. Heterocyclic Chemistry; Fourth Edition; J.A. Joule and K.Mills; Blackwell Science Ltd., London, 2000.
  3. Heterocyclic Chemistry; T.L. Gilchrist; Longman Scientific and Technical.
  4. An Introduction to the Chemistry of Heterocyclic Compounds; Second Edition; R.M. Acheson; John Wiley and Sons, New Delhi, 1976.
  5. Contemporary Heterocyclic Chemistry; G.R. Newkome and W.W. Paudler; Wiley Interscience.