A Radical-Initiated Fragmentary Rearrangement Cascade of Ene-Ynamides to [1,2]-Annulated Indoles via Site-Selective Cyclization
Sifan Li, Yu Wang, Zibo Wu, Weiliang Shi, Yibo Lei, Paul Davies, Wei Shu
Abstract
Straightforward access to [1,2]-annulated indoles, key substructures in natural products, is highly desirable yet challenging. Herein, a radical triggered fragmentary cyclization cascade reaction of ene-ynamides is presented, providing a rapid access into [1,2]-annulated indoles by an intermolecular radical addition, intramolecular cyclization, desulfonylative aryl migration, and site-selective C(sp2)-N cyclization sequence. DFT calculations support oxidation of N-centered radical species to cations prior to the C–N bond formation, followed by an unusual aza-Nazarov cyclization.
Topics & Concepts
ChemistryRadical cyclizationEne reactionIntramolecular forceIntermolecular forceCascadeArylStereochemistryCombinatorial chemistryMedicinal chemistryMoleculeOrganic chemistryAlkylChromatographyCatalytic Alkyne ReactionsCatalytic C–H Functionalization MethodsCyclopropane Reaction Mechanisms