title: Palladium-catalyzed thiocarbonylation of aryl, vinyl, and benzyl bromides.
abstract: A catalytic protocol for synthesis of thioesters from aryl, vinyl, and benzyl bromides as well as benzyl chlorides was developed using only stoichiometric amounts of carbon monoxide, produced from a solid CO precursor inside a two-chamber system. As a catalytic system, the combination of bis(benzonitrile) palladium(II) chloride and Xantphos furnished the highest yields of the desired compounds, along with the weak base, NaOAc, in anisole at 120 °C. The choice of catalytic system as well as solvent turned out to be important in order to ensure a high chemoselectivity in the reaction. Both electron-rich and electron-deficient aryl bromides worked well in this reaction. Addition of 1 equiv of sodium iodide to the reaction improved the chemoselectivity with the electron-deficient aryl bromides. The thiol scope included both aryl and alkyl thiols, including 2-mercaptobenzophenones, whereby a thiocarbonylation followed by a subsequent McMurry coupling yielded differently substituted benzothiophenes. It was demonstrated that the methodology could be applied for (13)C introduction into the thiophene ring.
authors.affiliation: Center for Insoluble Protein Structures, Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University , Gustav Wieds vej 14, 8000 Aarhus C, Denmark.
authors.forename: Mia N
authors.initials: MN
authors.lastname: Burhardt
authors.forename: Andreas
authors.initials: A
authors.lastname: Ahlburg
authors.forename: Troels
authors.initials: T
authors.lastname: Skrydstrup
mesh_terms: D001593:Benzyl Compounds / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry*; D002384:Catalysis; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D001593:Benzyl Compounds; D002247:Carbon Isotopes; D013438:Sulfhydryl Compounds; D014753:Vinyl Compounds; D010165:Palladium; C021292:benzyl chloride; C038682:benzyl bromide