Diels-Alder Reactions of Heterocyclic Azadienes: Total Synthesis of PDE-II Methyl Ester

Article abstract of DOI:10.1021/jo00366a048

The total synthesis of the methyl ester of PDE-II (2), a 3',5'-c-AMP phosphodiesterase inhibitor constituting the central and right-hand 1,2-dihydro-3H-pyrrolo<3,2-e>indole segment of the potent antitumor-antibiotic CC-1065, is described and is based on the utilization of two heterocyclic azadiene Diels-Alder reactions: an inverse electron demand Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate and a subsequent intramolecular Diels-Alder reaction of an alkyne 1,2-diazine.