A general and practicable synthesis of polycyclic heteroaromatic compounds. Part 3. Extension of the synthesis to ‘quinone methides’ of naphthalene, phenanthrene, and benzene

Abstract

The general synthesis of polycyclic heteroaromatic compounds by generation of a quinone methide in the presence of an aromatic amine has been successfully extended to naphthalene and phenanthrene ‘quinone methides’. Whereas yields had been highest when the putative quinone methides of less aromatic compounds were generated by a retro-Diels–Alder process, this method was inappropriate for the ‘quinone methides’ of more aromatic compounds. Good yields were obtained for the naphthalene and phenanthrene series when the ‘quinone methides’ were generated by pyrolysis of a Mannich base. Attempts to extend the synthesis of benzenoid quinone methides gave low yields of the polycyclic heteroaromatic product.