Oxidative Cyclization Reactions of Tryptamine Utilizing Hypervalent Iodobenzene in Routes for Pyrroloindole Alkaloid Synthesis

Oxidative cyclization of N-acetyltryptamine by using iodobenzene diacetate (PIDA) provided the corresponding 1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indol-3a-ol derivative, which could be derivatized following appropriate protection of the two amino and tert-hydroxyl groups. The facile one-pot procedure for cyclization and introduction of the oxygen functionality was applied in concise routes for the synthesis of the natural products CPC-1 and debromoflustraminol B.