| dc.description.abstract | : Using photochemical electron transfer, N,N-dimethylnaphthylamine derivatives are added to R,β-unsaturated
carboxylates. The addition takes place exclusively in the Rposition 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 TiO2. | en_US |
