Zusammenfassung
Beim Cyclohexan und seinen Abkömmlingen kann man die nicht an der Ringbildung beteiligten Valenzen der Kohlenstoffatome in «äquatoriale» und «polare» einteilen. Jedes Ringkohlenstoffatom hat eine polare und eine äquatoriale Bindung.
An einem gegebenen Kohlenstoffatom ist ein äquatorial gebundener Ligand thermodynamisch stabiler als ein polar gebundener. Zwei benachbarte Substituenten werden, wenn es sich um Ionenreaktion handelt, leichter abgespalten, wenn sie beide «polar» gebunden sind, als wenn einer von ihnen oder beide «äquatoriale» Bindungen besetzen. Ein Ligand in der polaren Stellung an einem gegebenen Kohlenstoffatom unterliegt stärkerer sterischer Hinderung als in der äquatorialen Anordnung.
Die Anwendung dieser allgemeinen. Regeln auf die Steroidchemie wird kurz beschrieben. Dabei wird die Abhängigkeit dieser Anwendung von der für den Sterinkern angenommenen Konfiguration betont.
Die Ausdehnung dieser Ideen auf das Gebiet der Di-und Triterpenoide wird angedeutet.
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References
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The word conformation is used to denote differing strainless arrangements in space of a set of bonded atoms. In accordance with the tenets of classical stereochemistry, these arrangements represent only one molecular species.
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Barton, D.H.R. The conformation of the steroid nucleus. Experientia 6, 316–320 (1950). https://doi.org/10.1007/BF02170915
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DOI: https://doi.org/10.1007/BF02170915