Dearomatization reaction

A dearomatization reaction is an organic reaction which involves arenes as reactants and in which the reaction products have permanently lost their aromaticity. [1] This reaction type is of some importance in synthetic organic chemistry for the organic synthesis of new building blocks [1] and in total synthesis. [2] Several methods for the dearomatization of carbocyclic arenes exist: hydrogenation (Birch reduction) , alkylative dearomatization, photochemical dearomatization, thermal dearomatization, oxidative dearomatization, dearomatization with transition metals and enzymatic dearomatization. [1]


Photochemical dearomatization

Examples of photochemical reactions are those between certain arenes and alkenes forming [2+2] and [2+4] cycloaddition adducts. [1]

Enzymatic dearomatization
Main article: Microbial arene oxidation

Examples of enzymes capable of arene dearomatization [3][4] are toluene dixoyhydrogenase, napthalene dixoyhydrogenase and benzoyl CoA reductase. [1]

Transition-metal assisted dearomatization

A classic example of transition-metal assisted dearomatization is the Buchner ring expansion [1] Catalytic asymmetric dearomatization reactions (CADA) are used in enantioselective synthesis. [5]


References
  1. 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
  2. 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
  3. 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
  4. Dearomatizing Benzene Ring Reductases Boll M. J Mol Microbiol Biotechnol 2005;10:132–142 doi:10.1159/000091560
  5. 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
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