MODELS OF FOLATE COFACTORS - 22. LEWIS ACID CATALYZED CYCLIZATION OF CARBON-FRAGMENT TRANSFER PRODUCTS OF FOLATE COFACTOR MODELS. SYNTHESIS OF ENANTIOMERICALLY PURE TETRACYCLIC (ABCE) RING SYSTEM OF ASPIDOSPERMA ALKALOIDS.

Article abstract of DOI:10.1016/S0040-4020(01)86452-8

Michael adducts of tryptamine, N(1)-methyltryptamine and tryptophane with acrylic esters react with substituted imidazolidines (N(5),N(10)-methylenetetrahydrofolate models) to give enaminones which cyclize under influence of Lewis acid, to give mixtures of tetrahydro-1H-pyrido<3,4-b>indoles and pyrrolo<2,3-d>carbazoles.The influence of the nature of Lewis acid on product formation is discussed.The synthesis of an enantiomerically pure pyrrolo<2,3-d>carbazole system is reported.