The Diels–Alder reactions of o-benzoquinones with acyclic dienes
Abstract
Diels–Alder reactions of acyclic dienes with o-benzoquinone and mono-, di-, and tri-substituted o-benzoquinones are reported. In these reactions the quinone always acts as a dienophile, with addition to the more electron-deficient olefinic linkage occurring preferentially. The adducts which are capable of aromatisation are labile, and in some cases only the aromatised adduct is isolated. These aromatised adducts, being 1,4-dihydronaphthalenes, are thermally unstable and readily lose hydrogen to give the corresponding naphthalene derivatives.