Access to the noryohimban [6,5,6,5,6] ring system via an intramolecular furan Diels–Alder reaction

Polycyclic indolic compounds containing the [6,5,6,5,6] ring system were prepared via an intramolecular furan Diels–Alder reaction of α,β-unsaturated amides generated by the N-acylation of 1-(2-furyl)-β-tetrahydrocarbolines. This chemistry can provide access to D(14)-noryohimban derivatives by exploiting the functionality on the C,D,E ring system of the corresponding cycloadducts.