Zwitterionic Character of Singlet 2-alkoxy-1,3-diyls: Mechanism of 1,2-Oxygen Migration Reaction

Abstract

Singlet diradicals are important intermediates in processes involving bond-formation and bond-cleavage. However, so far, the singlet diradicals are only the putative intermediates due to the short-lived species. Recently, we have found the singlet ground state and the log-lived singlet 2,2-dialkoxy-cyclopentane-1,3-diyls. The singlet ground state is explained by the hyperconjugative stabilization of the lowest singlet state. In the present study, the regioselective 1,2-oxygen migration was observed for the unsymmetrically substituted diradicals, which clearly supports that the hyperconjugative resonance structures are included in the singlet diradicals.