Total Synthesis of (±)-Herbindole A, (±)-Herbindole B, and (±)-cis-Trikentrin A

Herein we describe a divergent total synthesis of the title compounds utilizing Diels−Alder reactions of monoimine quinoids, followed by cyclization of the aromatized adducts to generate the tricyclic skeletons. Elaboration to iodinated or triflated indole derivatives allows for installation of the requisite alkyl substitution via cross-coupling reactions.