Note(s) In the absence of an indication to the contrary (such as the mention of isatoic anhydride in Fulltext... Hierarchy... Expanded...C07D 87/10), the cyclic anhydride of a polycarboxylic acid is classified with the acid in Fulltext... Hierarchy... Expanded...C07C. In this sub-class - When applying the "last place" rule, it is necessary to remember that the rule only applies in the absence of an indication to the contrary. Such an indication may take the form of a group specifically worded to cover particular compounds, e.g. "Fulltext...
Hierarchy... Expanded...C07D 91/52.....Thiazolo-pyrimidines", which substances might otherwise have been classified in Fulltext... Hierarchy... Expanded...C07D 99/00) - The indication may also take the form of the phrase "condensed with one or more other rings", and in this case the term "other rings" includes any ring except one which is covered later in Fulltext...
Hierarchy... Expanded...C07D. Thus, for example, in spite of the wording of the Guide Heading before Fulltext... Hierarchy... Expanded...C07D 59/00, the compound is to be found in Fulltext... Hierarchy... Expanded...C07D 63/18, and not under Fulltext... Hierarchy... Expanded...C07D 99/00, as might have been supposed at first sight. It is also to be noted that there is no specific mention under Fulltext... Hierarchy... Expanded...C07D 63/00 of tetrahydrothiophene condensed with one or more other rings, but the use in Fulltext... Hierarchy... Expanded...C07D 63/02 of the plural form of the name implies that this group includes those compounds, the term "other rings" having the same meaning as give above. This is covered by Fulltext... Hierarchy... Expanded...C07D 63/02. It is also noteworthy that the alkaloids scopoline, morphine, and strychnine have for convenience been places under Fulltext... Hierarchy... Expanded...C07D 43/00, although they contain heterocyclic oxygen, and do not, accordingly, fit strictly under the Guide Heading before Fulltext... Hierarchy... Expanded...C07D 23/00. - A further complication arises in the case of condensed ring systems, namely: which rings must be taken into account when determining the classification. The rule is as follows: Only single rings are to be considered, and bridged rings are to be ignored except where the bridged-ring system is one, such as quinoline, which is specifically named in the classification. Thus in the case of the compound
only te two C5N rings are considered, and not the bridged C8N2 one, and the correct classification is under Fulltext... Hierarchy... Expanded...C07D 39/00 and not under Fulltext... Hierarchy... Expanded...C07D 53/00).
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