Fused Ring and Bridged Fused Ring Nomenclature
(IUPAC Recommendations 1998)

FR-6 Multi-Parent Systems

Continued from FR-5 Numbering

Contents of Section

FR-6. Multi-Parent Systems
FR-6.1 Multi-parent systems with one interparent component
FR-6.2 Additional attached components
FR-6.3 Multi-parent systems with three or more interparent component

Continue with FR-7 Three Components ortho- and peri-Fused Together.

FR-6 Multiparent Systems

When there are two or more non-overlapping locations for the parent component (see FR-3.3) and they are ortho- or ortho- and peri-fused to the same first order interparent component (see FR-1.3.3) they are treated as multiparent system and given a multiparent name. Similarly a system with three, five, seven, etc. interparent components is treated as an extended multiparent system. Each pair of second- or higher-order interparent components must be identical.

FR-6.1 Multiparent systems with one interparent component

The multiple occurences of the parent component in a multiparent system is indicated by the use of the prefix di-, tri-, etc. (or bis-, tris-, etc. see FR-4.9). To distinguish between the parent components the second one has primed letters, the third double primed etc. and the sets of locant are separated by a colon.







FR-6.2 Additional attached components

Additional attached components may be fused to any of the components of a multiparent system. If FR-4.5 does not provide the preferred locants preference is given to the unprimed component and the fusion letters are assigned with the lower letter used for fusion to the connecting component. Great care is needed with the use of primes, double primes etc. to ensure that there is no ambiguity. Thus additional components fused to the interparent component(s) are cited next to the prefix for this interparent component.





The furan ring is fused to the interparent component so that alphabetic order does not apply.

FR-6.3 Multiparent systems with three or more interparent components

If two (or more) possible parent components are separated by an odd number of interparent components and these are ordered symmetrically with respect to their component rings (but not necessarily with respect to their fusion locants) the whole system is treated as a multiparent system. Second- and higher-order interparent components are named using the prefix di-, tri-, etc. (or bis-, tris-, etc. if appropriate).



or benzo[1",2":3,4;4",5":3',4']bis(cyclobuta[1,2-c]furan)


This alternative method of naming symmetric systems is not used by CAS. Beilstein applies it to systems with five or more interparent components.

or benzo[1"',2"':3,4;3"',4"':3',4';5"',6"':3",4"]tris(cyclobuta[1,2-c]furan)



Continue with FR-7 Three Components ortho- and peri-Fused Together.

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