Rule F-4.2 (Modification of the Parent Structure)

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Modification of the Parent Structure

Rule F-4.2

Elimination of one methylene group from a side chain of a parent structure (including a methyl group) is indicated by the prefix "nor", which in all cases is preceded by the locant of the carbon atom that disappears. When alternatives are possible, The locant attached to "nor" is the highest permissible. Elimination of two or more methylene groups is indicated by the prefix "dinor", "trinor", again with citation of all locants.

Examples to Rule F-4.2

Apotrichothecane

13-Norapotrichothecane

Germacrane

13-Norgermacrane

Note: The special usage for monoterpenes (see Rules A-72.1 and A-74.2), whereby the prefix "nor" (without multiplying prefix) denotes replacement by hydrogen of all methyl groups attached to a ring system, is abolished (see Rule C-42.1) and Rules A-72 to A-75, are superseded.

Examples to Rule F-4.2

Bornane

10-Norbornane

8,9,10-Trinorbornane
(previously norbornane)

This HTML reproduction of Sections A, B and C of IUPAC "Blue Book" is as close as possible to the published version [see Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, Oxford, 1979. Copyright 1979 IUPAC.] If you need to cite these rules please quote this reference as their source.

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