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Polycyclic Systems
Both nature
and mankind has created many examples
of compounds that contain more than one ring system. These can be
classified
depending on how many rings are present and how the rings are joined
together.
| If there is a single carbon atom common
to two rings, then the system
is said to be "spirocyclic" and the carbon can be
described
as the "spirocenter". The simplest example is
spiropentane.
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| If two or more atoms are shared between
more than one ring then the
system is said to be "polycyclic" in general terms or as
bicyclic, tricyclic, tetracyclic etc. depending on how many rings
systems
are present. The simplest polycyclic system is
bicyclobutane.
When there are two common atoms in the rings, then it is a "fused" system, as in bicyclobutane.
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| If there are more than two common atoms
then the a "bridged"
system is obtained, the simplest example being
bicyclo[1.1.1]pentane.
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Some interesting examples are
shown below.
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© Dr. Ian Hunt, Department of Chemistry |  |