Structures of Bicyclic Heteroaromatic Compounds

Once the ideas of the structures of benzene, naphthalene, pyridine and pyrrole, as prototypes, have been assimilated it is straightforward to extrapolate to those systems which combine two (or more) of these types, thus qiiinoline is like naphthalene, only with one of the rings a pyridine, and indole is like pyrrole, but with a benzene ring attached. 

Resonance representations must take account of the pattern established for benzene and the relevant heterocycle. Contributors in which both aromatic rings are disrupted make a very much smaller contribution and are shown in parentheses. 

Structure of quinoline resonance contributors (mesomeric structures) 

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Biological pyrimidines, tautomerism and electronic structure of, 18, 199 Bipyridines, 35, 281 Boron-substituted heteroaromatic compounds, 46, 143 Bridgehead nitrogen saturated bicyclic 6/5 ring-fused systems with, 49, 193... 

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