title: A new family of nucleophiles for photoinduced, copper-catalyzed cross-couplings via single-electron transfer: reactions of thiols with aryl halides under mild conditions (O °C).
abstract: Building on the known photophysical properties of well-defined copper-carbazolide complexes, we have recently described photoinduced, copper-catalyzed N-arylations and N-alkylations of carbazoles. Until now, there have been no examples of the use of other families of heteroatom nucleophiles in such photoinduced processes. Herein, we report a versatile photoinduced, copper-catalyzed method for coupling aryl thiols with aryl halides, wherein a single set of reaction conditions, using inexpensive CuI as a precatalyst without the need for an added ligand, is effective for a wide range of coupling partners. As far as we are aware, copper-catalyzed C-S cross-couplings at 0 °C have not previously been achieved, which renders our observation of efficient reaction of an unactivated aryl iodide at -40 °C especially striking. Mechanistic investigations are consistent with these photoinduced C-S cross-couplings following a SET/radical pathway for C-X bond cleavage (via a Cu(I)-thiolate), which contrasts with nonphotoinduced, copper-catalyzed processes wherein a concerted mechanism is believed to occur.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Uyeda
authors.forename: Yichen
authors.initials: Y
authors.lastname: Tan
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Fu
authors.forename: Jonas C
authors.initials: JC
authors.lastname: Peters
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D004579:Electron Transport; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D015394:Molecular Structure; D055668:Photochemical Processes; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013696:Temperature
chemical_list: D006846:Hydrocarbons, Halogenated; D013438:Sulfhydryl Compounds; D003300:Copper