Synthesis of indole compounds using multifunctional synthons

This review describes a synthesis of indole compounds using multifunctional synthons. The multifunctional synthons, trienes and gramines, were respectively synthesized using Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborate with vinyl bromide, and reaction of indolylcuprate with iminium chloride. As an application of the multifunctional synthons to the indole alkaloids synthesis, we accomplished the total synthesis of ellipticine, 9-methoxyellipticine, 9-hydroxyellipticine, tetrahydroellipticine, μ-alkaloid B, μ-alkaloid D, calothrixin A, calothrixin B, tubifoline, and yuehchukene. We have also developed 6π-electrocyclization of hexatrienes catalyzed by Cu(I) trifluoromethanesulfonate toluene complexe, which is unprecedented.