Base-induced benzoyl migrations in Diels–Alder adducts of benzoyl-1,4-benzoquinones

Abstract

Addition of buta-1,3-diene and trans-penta-1,3-diene to substituted benzoyl-1,4-benzoquinones affords the corresponding 4a-benzoyl-4a,5,8,8a-tetrahydro-1,4-naphthoquinones which in pyridine and pyridine–methanol, undergo [1,5] and [1,2] benzoyl shifts to give 2-benzoyl-5,8-dihydro-1,4-dihydroxynaphthalenes; the effects of para-substituents in the benzoyl group on the kinetices and regiospecificity of the migration are described.