Aromatisation of Six-Membered Rings
Aromatization of Six-Membered Rings: Oxidation with Quinone
In this reaction, quinones are reduced to the corresponding hydroquinones. Mechanistically, a hydride anion is transferred to a quinone oxygen atom, followed by addition of a proton to the the newly formed phenolate anion. Alternatively, electron transfer mechanisms are being discussed.
Electron-poor quinones, such as chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone) and DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) are especially reactive with the latter a better substrate than the former.