title: Metal-free carbonylations by photoredox catalysis.
abstract: The synthesis of benzoates from aryl electrophiles and carbon monoxide is a prime example of a transition-metal-catalyzed carbonylation reaction which is widely applied in research and industrial processes. Such reactions proceed in the presence of Pd or Ni catalysts, suitable ligands, and stoichiometric bases. We have developed an alternative procedure that is free of any metal, ligand, and base. The method involves a redox reaction driven by visible light and catalyzed by eosin Y which affords alkyl benzoates from arene diazonium salts, carbon monoxide, and alcohols under mild conditions. Tertiary esters can also be prepared in high yields. DFT calculations and radical trapping experiments support a catalytic photoredox pathway without the requirement for sacrificial redox partners.
authors.affiliation: Institute of Organic Chemistry, University of Regensburg, Universitaetsstrasse 31, 93040 Regensburg (Germany).
authors.forename: Michal
authors.initials: M
authors.lastname: Majek
authors.forename: Axel
authors.initials: A
authors.lastname: Jacobi von Wangelin
mesh_terms: D000438:Alcohols / Q000737:chemistry; D000478:Alkylation; D001565:Benzoates / Q000138:chemical synthesis* / Q000737:chemistry; D002248:Carbon Monoxide / Q000737:chemistry; D002384:Catalysis; D003979:Diazonium Compounds / Q000737:chemistry; D004801:Eosine Yellowish-(YS) / Q000737:chemistry*; D004952:Esters; D008027:Light; D010084:Oxidation-Reduction; D055668:Photochemical Processes
chemical_list: D000438:Alcohols; D001565:Benzoates; D003979:Diazonium Compounds; D004952:Esters; D002248:Carbon Monoxide; D004801:Eosine Yellowish-(YS)
keywords: carbonylation; esters; organocatalysis; photoredox catalysis; redox reaction; visible light