Annulation

Source: Wikipedia, the free encyclopedia.
Not to be confused with Annulment.

In

Latin anellus 'little ring'; occasionally annelation) is a chemical reaction in which a new ring is constructed on a molecule.[1]

Annulation: A) intramolecular ring closing B) transannulation C) cycloaddition

Examples are the

cyclization of 5-methylenecyclooctanone which proceeds through a ketyl intermediate:[2]

Ketone olefin cyclization

Benzannulation

The term benzannulated compounds refers to derivatives of cyclic compounds (usually aromatic) which are fused to a benzene ring. Examples are listed in the table below:

Benzannulated derivative Source of cyclic compound
Benzopyrene Pyrene
Quinoline Pyridine
Isoquinoline
Chromene
 Pyran
Isochromene
Indole Pyrrole
Isoindole
Benzofuran Furan
Isobenzofuran
Benzimidazole Imidazole

In contemporary chemical literature, the term benzannulation also means "construction of benzene rings from acyclic precursors".[3]

Protonation of Verkade base induces a transannular bonding, giving an atrane.[4]

Transannular interaction

A transannular interaction in chemistry is any chemical interaction (favorable or nonfavorable) between different non-bonding molecular groups in a large ring or macrocycle.[5] See for example atranes.

References

  1. doi:10.1351/goldbook.A00365.html
  2. doi:10.1021/jo062292d
  3. S2CID 244403005
    .
  4. ISBN 978-0471936237
    .
  5. ^ Experimental evidence in support of transannular interactions in diketones Kata Mlinaric-Majerski, Marijana Vinkovic, Danko Škare, Alan P. Marchand Arkivoc DS-339E 2002 Online Article Archived 2006-05-04 at the Wayback Machine
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