Synthesis of a tetracyclic substructure of manzamine A via the Diels-Alder reaction of dihydropyridinones

Article abstract of DOI:10.1016/0040-4020(96)00607-2

Synthesis of the tetracyclic core (19) of manzamine A (1) was achieved via Diels-Alder reaction of the dihydropyridinones (5, 6). Conversion of the two D-A products (7, 8) to the key tricyclic ketone (10) was conducted through a conventional pathway as well as a new pathway developed. For effective construction of the required azocine ring systems, model studies were carried out to find intramolecular amide formation by pentafluorophenyl ester and DPPA methods, which were successfully applied to the real substrate to furnish the titled core structure (19).