title: Transition-Metal-Free C3 Arylation of Indoles with Aryl Halides.
abstract: We report an unprecedented transition metal-free coupling of indoles with aryl halides. The reaction is promoted by KOtBu and is regioselective for C3 over N. The use of degassed solvents devoid of oxygen is necessary for the success of the transformation. Preliminary studies implicate a hybrid mechanism that involves both aryne intermediates and non-propagative radical processes. Electron transfer is also a distinct possibility. These conclusions were substantiated by EPR data, isotopic labeling studies, and the use of radical scavengers and electron transfer inhibitors.
authors.affiliation: Department of Chemistry, Dartmouth College, Hanover, NH, 03755, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Dartmouth College, Hanover, NH, 03755, USA.
authors.forename: Jimmy
authors.identifier: 0000-0002-0938-8019
authors.initials: J
authors.lastname: Wu
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D006846:Hydrocarbons, Halogenated; D007211:Indoles; D028561:Transition Elements
keywords: aryne; cross-coupling; indole; radicals; transition metal-free synthesis