Iron-Mediated Hydrogen Atom Transfer Radical Cyclization of Alkenyl Indoles and Pyrroles Gives Their Fused Derivatives: Total Synthesis of Bruceolline E and H

Abstract

The iron-mediated hydrogen atom transfer (HAT) reaction is efficaciously employed for the synthesis of dihydropyrroloindoles and dihydropyrrolizines via 5-exo-trig radical cyclization where indoles and pyrroles are used as an acceptor. This radical approach has also been extended for the synthesis of tetrahydrocyclopenta [b]indolones via the Baldwin-disfavored 5endo-trig cyclization pathway. The formal synthesis of bruceolline J and the total synthesis of bruceollines E and H have been expeditiously carried out by employing the former strategy.

Iron-Catalyzed Oxidative Rearrangement of Cyclopropanone Hemiaminals: General Access to Pyrroloindolones from Indoles

“…Specifically, pyrroloindolones and related 1,2-fused indole natural products have recently emerged as promising therapeutic agents for a variety of diseases . While a number of synthetic approaches exist for their formation, most rely on the multistep prefunctionalization of substrates prior to cyclization, − the use of expensive and/or elaborate metal complexes as catalysts, − or only give access to specific substitution patterns on the resulting pyrroloindolone. − Therefore, the development of alternative sustainable strategies leading to a general access to the pyrroloindolone scaffold from simple starting materials is highly desirable.…”