Oligomers, heterocyclic

Heterocyclic iminium salts, oxidative transformation, 41, 275 Heterocyclic mesomeric betaines and analogs in natural product chemistry, 85, 67 Heterocyclic oligomers, 15, 1 Heterocyclic products, natural, synthesis of by hetero Diels-Alder cycloaddition reactions, 42, 245... 

A aromatic and/or heterocyclic oligomer Z latent crosslinking agent for addition reaction... 

With the sole exception of photodimers,1 heterocyclic oligomers, that is to say heterocycles formed from two to five units of a monomer, have not previously been reviewed. This neglect is surprising, because heterocyclic oligomers are both common and interesting. They arise frequently as by-products in the synthesis of heterocycles and sometimes they form the main product of the reaction. Very often, they are crystalline products, easily purified and characterized. In recent years, the constitution of many examples has been elucidated by taking advantage of modern physical methods. 

When an oligomer has the structure which belongs to more than one class, the Prinzip der spatesten Systemstdle is applied. The discussion of each class will be developed in the following order, based on the nature of the monomer (1) heterocyclic oligomers from nonheterocyclic monomers, (2) heterocyclic oligomers from heterocyclic monomers,... 

Subclass 1. Heterocyclic Oligomers from Nonheterocyclic Monomers... 

Subclass 4. Naturally Occurring Heterocyclic Oligomers (Including Their Synthesis)... 

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