Acyl migrations in Diels–Alder adducts of acyl-1,4-benzoquinones
Abstract
Treatment of several 4a-acyl-4a,5,8,8a-tetra-hydro-1,4-naph thoquinones with boiling acetic anhydride gives the 1,4-diacetoxy-2-acyl-5,8-dihydronaphthalenes, and the corresponding 1,4-dihydroxy-compounds are formed when acetic acid is used, but the latter are more readily obtained, via the Δ8a,1enols, by treatment with pyridine or pyridine–methanol, these basic reagents cause deformylation of the 4a-formyl analogues, but transfer of the formly group to the oxygen at C-4 can be effected with imidazole.