Bridgehead atoms

Bridgehead atoms ( English bridgehead atom ) are in Chemistry - more precisely in the structural formulas of chemical compounds - known atoms in larger molecules , such. B. in bridged bicyclic ring systems. The bridgehead atoms are usually carbon atoms , but there are also compounds with two nitrogen bridgehead atoms, for example diazabicyclooctane ( DABCO ). Also, the Tröger's base containing two nitrogen-bridgehead atoms, which also stereocenters represent that does not invert , since the pyramidal configuration is stable.

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  Norbornane - the two blue arrows point to the bridgehead atoms (carbon atoms)

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  Diazabicyclooctane (DABCO) with the two bridgehead atoms marked blue (nitrogen atoms)

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  Adamantane - the four blue arrows point to the bridgehead atoms (carbon atoms)

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  Enantiomers of Tröger's base each with two bridgehead atoms marked blue (nitrogen atoms)

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  Twistan - the four blue arrows point to the bridgehead atoms (carbon atoms)

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  Tetrahedrane , C ₄ H ₄ , contains four bridgehead atoms (carbon atoms)

Adamantane contains four bridgehead carbon atoms, as does Twistan . Camphor and cocaine are natural substances that each contain two carbon bridgehead atoms.

The formation of a double bond in a molecule with the participation of a bridgehead atom is often difficult, ie such cycloalkenes are often unstable. This subject is the subject of Bredt's rule .

Bridgehead carbon atoms are found in

• condensed or fused polycyclic alkanes (simple example: decalin , in which two cyclohexane rings share two carbon atoms)

or in

• bridged bicyclic ring systems (simple example: norbornane ).

Individual evidence

1. ↑ Jonathan Clayden, Nick Greeves, Stuart Warren: Organische Chemie , Springer Spectrum, 2013, 2nd edition, pp. 920–921. ISBN 978-3-642-34715-3 .
2. ↑ Michael B. Smith: March's advanced organic chemistry , John Wiley & Sons, 7th edition, 2013, p. 129, ISBN 978-0-470-46259-1 .
3. ^ Siegfried Hauptmann : Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 227, ISBN 3-342-00280-8 .
4. ↑ K. Peter C. Vollhardt: Organische Chemie , VCH, 1990, pp. 164-165, ISBN 3-527-26912-6 .