A dearomatization reaction is an

organic reaction Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, Mechanistic Organ ...

which involves arenes as reactants and in which the reaction products have permanently lost their

aromaticity In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to saturate ...

. This reaction type is of some importance in synthetic organic chemistry for the organic synthesis of new building blocks and in

total synthesis Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes ...

. Several methods for the dearomatization of carbocyclic arenes exist: hydrogenation (

Birch reduction The Birch reduction is an organic reaction that is used to convert arenes to cyclohexadienes. The reaction is named after the Australian chemist Arthur Birch and involves the organic reduction of aromatic rings in an amine solvent (traditionally ...

), alkylative dearomatization, photochemical dearomatization, thermal dearomatization, oxidative dearomatization, dearomatization with transition metals and enzymatic dearomatization.

Photochemical dearomatization

Examples of photochemical reactions are those between certain arenes and alkenes forming +2and +4

cycloaddition In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of th ...

adducts.

Enzymatic dearomatization

Examples of enzymes capable of arene dearomatization are toluene dixoyhydrogenase, naphthalene dixoyhydrogenase and benzoyl CoA reductase.

Transition-metal assisted dearomatization

A classic example of transition-metal assisted dearomatization is the

Buchner ring expansion The Buchner ring expansion is a two-step organic C-C bond forming reaction used to access 7-membered rings. The first step involves formation of a carbene from ethyl diazoacetate, which cyclopropanates an aromatic ring. The ring expansion occ ...

Catalytic asymmetric dearomatization reactions (CADA) are used in enantioselective synthesis.

References

{{reflist, colwidth=50em , refs= Pigge, F. C. (2015) ''Dearomatization Reactions, in Arene Chemistry: Reaction Mechanisms and Methods for Aromatic Compounds'' (ed J. Mortier), John Wiley & Sons, Inc, Hoboken, NJ. {{doi, 10.1002/9781118754887.ch15 Roche, S. P. and Porco, J. A. (2011), ''Dearomatization Strategies in the Synthesis of Complex Natural Products.'' Angew. Chem. Int. Ed., 50: 4068–4093. {{doi, 10.1002/anie.201006017 ''Dearomatizing Benzene Ring Reductases'' Boll M. J Mol Microbiol Biotechnol 2005;10:132–142 {{doi, 10.1159/000091560 ''Anaerobic degradation of homocyclic aromatic compounds via arylcarboxyl-coenzyme A esters: organisms, strategies and key enzymes''. Boll M, Löffler C, Morris BE, Kung JW. Environ Microbiol. 2014 Mar;16(3):612-27. {{doi, 10.1111/1462-2920.12328 Zhuo, C.-X., Zhang, W. and You, S.-L. (2012), ''Catalytic Asymmetric Dearomatization Reactions''. Angew. Chem. Int. Ed., 51: 12662–12686. {{doi, 10.1002/anie.201204822 Organic reactions