title: Photoinduced decarboxylative benzylation of phthalimide triplets with phenyl acetates: a mechanistic study.
abstract: The photodecarboxylative benzylation of N-alkyl, N-arylalkyl, and N-aryl phthalimides with arylacetic acids in aqueous solution proceeds via electron transfer from the arylalkanoate to the excited triplet state of the phthalimide, either formed directly or upon sensitization with acetone. The rate constant for triplet quenching of N-methylphthalimide is k(q) < 10(7) M(-1) s(-1) for 2-phenylacetic acid and k(q) = (1-3) x 10(9) M(-1) s(-1) for its mono-, di- and trimethoxy-substituted derivatives, suggesting a change of the mechanism for the primary oxidation step from a Photo-Kolbe type reaction yielding an acyloxy radical to a pseudo-Photo-Kolbe process involving the formation of resonance-stabilized zwitterion radicals as intermediates.
authors.affiliation: Institute of Organic Chemistry, University of Cologne, Greinstrasse 4, D-50939 Köln, Germany. klaus.warzecha@uni-koeln.de
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Warzecha
authors.forename: Helmut
authors.initials: H
authors.lastname: Görner
authors.forename: Axel G
authors.initials: AG
authors.lastname: Griesbeck
mesh_terms: D000838:Anions / Q000737:chemistry; D001554:Benzene / Q000737:chemistry*; D004579:Electron Transport; D004735:Energy Transfer; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010648:Phenylacetates / Q000737:chemistry*; D010777:Photochemistry; D010797:Phthalimides / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
chemical_list: D000838:Anions; D010648:Phenylacetates; D010797:Phthalimides; D014867:Water; C037431:phthalimide; C025136:phenylacetic acid; D001554:Benzene