Nomenclature bridged ring systems

For clarity in the following discussion, structure (5.11) shows the numbering system of the 2,2,1-bicycloheptyl skeleton. This ring system nomenclature is based on the bridgehead carbon atoms. To name a bicyclic compound, one first identifies the two bridgehead carbon atoms and then counts the number of atoms in each bridge. Thus in structure... 

A bridged-ring system is one in which two alicyclic rings have two or more atoms in common. These atoms bridge-head atoms) do not have to be adjacent to one another. Such compounds have a unique numbering pattern and nomenclature. 

The alcohol portion in hyoscyamine is tropine in hyoscine it is the epoxide scopine. Tropine is an example of an azabicyclo[3,2,l]octane system with a nitrogen bridge, whereas scopine is a tricylic system with a three-membered epoxide ring fused onto tropine. Note that systematic nomenclature considers an all-carbon ring system with one carbon replaced by nitrogen hence, tropane is an azabicyclooctane (see Section 1.4). 

Nomenclature of Fused and Bridged Fused Ring Systems. 200... 

At this point, we can introduce an entirely different system of nomenclature that is nevertheless accepted by lUPAC and is extremely valuable in multicyclic and bridged saturated systems. This is the replacement system, where the hydrocarbon name that would correspond to the entire ring structure, as if no heteroatom were present, is stated, and then given a Hantzsch-Widman prefix and number for the heteroatom(s). Thus, phenanthridine shown previously has the ring framework of the hydrocarbon phenanthrene, with N at position 5. The replacement name would be 5-azaphenanthrene. 

Moss GP. Nomenclature of fused and bridged fused ring systems. Pure Appl Chem... 

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. 

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