On page 819 of Vollhardt, Organic Chemistry 7th Ed., the following "subunit of the antibacterial platensimycin" appears. I have attempted to apply von Baeyer and skeletal replacement ('a') nomenclature but am stuck deciding between numberings. Here are some vector drawings: 1

Is von Baeyer the preferred nomenclature for this molecule? and, if so, what is its correct numbering and preferred IUPAC name?

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    $\begingroup$ Pubchem has the first bridgehead as the spiro carbon, giving a lower index to one of the secondary bridges: 4-oxo-8-oxatetracyclo[$^{7,10}$.0$^{1,6}$]tridec-2-ene. I don't have access to the 2013 blue book, so I will refrain from writing an answer. (P- The superscript locants for the secondary bridges must be as low as possible when considered as a set in ascending numerical order, the decision being made at the first point of difference.) $\endgroup$
    – Karsten
    May 10, 2019 at 19:10
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    $\begingroup$ Instead of a von Baeyer name, Chemoffice as well as the usually good ACD/ChemSketch (2017.2.1) prefer a fusion name in this case, i.e. a structure based on 4a,7-methanobenzo[7]annulene. However, I still cannot prove why – when looking into the original IUPAC rules. The resulting name would be 4a,5,6,7,8,9-hexahydro-5,8-epoxy-7,9a-methanobenzo[7]annulen-3(4H)-one. $\endgroup$
    – user7951
    May 11, 2019 at 6:31

2 Answers 2


The pubchem website has given Platensimycin IUPAC name, $3$-$[3$-$[(1S,5S,6R,7S,9S,10S)$-$5,9$-dimethyl-$4$-oxo-$8$-oxatetracyclo$[^{7,10}.0^{1,6}]$tridec-$2$-en-$5$-yl]propanoylamino]-$2,4$-dihydroxybenzoic acid (see attached picture):


Accordingly, since https://pubchem.ncbi.nlm.nih.gov is usually updating data according to the changes, I believe the name of the cyclic system (without 5,9-dimethyl groups) OP is asking is same as one in the comment by @KarstenTheis (including the correct stereochemistry): $(1S,5S,6R,7S,9S,10S)$-$4$-oxo-$8$-oxatetracyclo$[^{7,10}.0^{1,6}]$tridec-$2$-ene (see the blue numbering in the picture).

Late correction: After exchanging few comments with Loong, I realized that the given system should be treated as a chemical compound. Accordingly, the name should have been: $(1S,5S,6R,7S,9S,10S)$-$4$-oxo-$8$-oxatetracyclo$[^{7,10}.0^{1,6}]$tridec-$2$-en-$4$-one (as suggested by Loong).

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    $\begingroup$ "since pubchem.ncbi.nlm.nih.gov is usually updating data according to the changes" – do we know that they are really doing this? $\endgroup$
    – user7951
    May 11, 2019 at 6:06
  • $\begingroup$ I have seen changing of data on physical properties section. But not sure for everything, though. $\endgroup$ May 11, 2019 at 6:10
  • $\begingroup$ How do we know that the correct name for the moiety as a substituent is the same as its correct name as its own molecule? $\endgroup$ May 12, 2019 at 20:06
  • $\begingroup$ Not exactly the same but related. See, the priority changes going from substituent to a molecule. For example, 4-oxo- for substituent becomes 4-one on the molecule. $\endgroup$ May 12, 2019 at 23:04
  • $\begingroup$ In the full IUPAC name for Platensimycin, why is it "-4-yl]propylamino" instead of "-5-yl]propylamino"? Isn't the tetracyclic part connected to the propylamino part at carbon 5? $\endgroup$ Jun 13, 2019 at 7:13

An elder version of Chemdoodle (8.1.0) suggests a name slightly different from the one in the comment by @KarstenTheis, 8-Oxotetracyclo$[^{7,10}.0^{1,6}]$-tridec-2-3n-4-one.

It may be that I erred while drawing the molecule into the sketcher, hence for a xcheck the screen photo below. The yellowish' spheres indicate Chemdoodle's selection for the current naming -- there are only two atoms of oxygen.

enter image description here


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