Spiro systems, nomenclature

The source-based nomenclature identifies the starting material(s) from which the ladder or spiro polymer is prepared. It is derived from the nomenclature system for copolymers [3]. The system is based on the following principles ... 

Polycyclic parent hydrides. These are classified as bridged polyalkanes (also known as von Baeyer bridged systems, from the nomenclature system developed to name them), spiro compounds, fused polycyclic systems and assemblies of identical rings. The four systems may be either carbocyclic or heterocyclic. In developing their names, the following principles are used. 

Systems that do not meet all the above specifications, but the use of which is acceptable because of their convenience or the lack of suitable alternatives are the bridging nomenclature, system 4, method b (in which saturated bridging groups are permitted), the spiro method, 6a, ii (in which the components may be fully unsaturated or saturated and retain their original numberings), and system 7 for assemblies of identical cyclic components. 

Replacement principles can be applied satisfactorily to all these systems in order to name heterocycles. Indeed, this is the only way in which the von Baeyer system and the spiro method 6a, i (i.e., the systems of type II see above) can be used in the heterocyclic series. However, as explained in Section II, B, 1, b, replacement nomenclature has not previously been applied extensively in other areas, although it has been used to a limited extent for fused skeletons. It is to be hoped that its use will increase. 

These latter two techniques are important both for spiro molecules in which the rings containing the common atom are of different constitution and for ring assembly compounds. Additionally, note that in many instances the other distinct types of nomenclature that had been introduced earlier [Cartesian (in Chapter 1) and cylindrical (in Chapter 3)] may be interconverted in much the same way as the different types of coordinate systems in geometry may be interconverted. 

Because of the cumbersome and usually exasperating nature of the von Baeyer system of formal nomenclature,422 especially when applied to complex polycyclic systems, a colloquial nomenclature has been developed for the higher poly-quinanes.415,42 The system applies only to polycondensed, fused, equal-size ringed molecules (no spiro fusions) and states the total number of carbon atoms, the number of basic rings, and their size. An indicator of ring juncture stereochemistry is also required on occasion, a symmetry designation must be added. Thus, all-cis-484 is (Q-C 14-tetraquinane and all-cis-485 is(C2)-Ci4-tetraquinane. 

Replacement nomenclature is also used for some heterocyclic systems, including von Baeyer systems (see Chapter 4), large rings (>10 members) and some spiro compounds. 

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