Applications of intramolecular diels-alder reactions of heterodienes. Facile syntheses of the heteroyohimbine alkaloids tetrahydroalstonine and akuammigine.

A facile, formal synthesis of the heteroyohimbine alkaloids tetrahydroalstonine (1) and akuammigine (2) has been completed in which the D/E ring system is constructed by the novel cyclization of the triene 10, a process which involves the intramolecular [4+2] cycloaddition of a heterodiene with an α,β-unsaturated amide.