title: Photochemical electron transfer mediated addition of naphthylamine derivatives to electron-deficient alkenes.
abstract: Using photochemical electron transfer, N,N-dimethylnaphthylamine derivatives are added to α,β-unsaturated carboxylates. The addition takes place exclusively in the α-position of electron-deficient alkenes and mainly in the 4-position of N,N-dimethylnaphthalen-1-amine. A minor regioisomer results from the addition in the 5-position of this naphthylamine. A physicochemical study reveals that the fluorescence quenching of N,N-dimethylnaphthalen-1-amine is diffusion-controlled and that the back electron transfer is highly efficient. Therefore no transformation is observed at lower concentrations. To overcome this limitation and to induce an efficient transformation, minor amounts of water or another proton donor as well as an excess of the naphthylamine derivative are necessary. A mechanism involving a contact radical ion pair is discussed. Isotopic labeling experiments reveal that no hydrogen is directly transferred between the substrates. The hydrogen transfer to the furanone moiety observed in the overall reaction therefore results from an exchange with the reaction medium. An electrophilic oxoallyl radical generated from the furanone reacts with the naphthylamine used in excess. Concerning some mechanistic details, the reaction is compared with radical and electrophilic aromatic substitutions. The transformation was carried out with a variety of electron-deficient alkenes. Sterically hindered furanone derivatives are less reactive under standard conditions. In a first experiment, such a compound was transformed using heterogeneous electron transfer photocatalysis with TiO(2).
authors.affiliation: Equipe de Photochimie, Institut de Chimie Moléculaire de Reims, UMR 6229 CNRS et Université de Reims Champagne-Ardenne, UFR Sciences, B.P. 1039, 51687 Reims, France.
authors.forename: Rabih
authors.initials: R
authors.lastname: Jahjah
authors.forename: Abdoulaye
authors.initials: A
authors.lastname: Gassama
authors.forename: Frédéric
authors.initials: F
authors.lastname: Dumur
authors.forename: Siniša
authors.initials: S
authors.lastname: Marinković
authors.forename: Sabine
authors.initials: S
authors.lastname: Richert
authors.forename: Stephan
authors.initials: S
authors.lastname: Landgraf
authors.forename: Aurélien
authors.initials: A
authors.lastname: Lebrun
authors.forename: Cyril
authors.initials: C
authors.lastname: Cadiou
authors.forename: Patrice
authors.initials: P
authors.lastname: Sellès
authors.forename: Norbert
authors.initials: N
authors.lastname: Hoffmann