Converting Strain Release into Aromaticity Loss for Activation of Donor–Acceptor Cyclopropanes: Generation of Quinone Methide Traps for C-Nucleophiles
Vitaly V. Shorokhov, Beauty K. Chabuka, Timur P. Tikhonov, Anastasia Filippova, Sergey S Zhokhov, В. А. Тафеенко, Ivan A Andreev, Nina K Ratmanova, Maxim G. Uchuskin, Igor V. Trushkov, Igor V. Alabugin, Оlga А. Ivanova
Abstract
Here, we present a new approach for the activation of donor–acceptor cyclopropanes in ring-opening reactions, which does not require the use of a Lewis or Brønsted acid as a catalyst. Donor–acceptor cyclopropanes containing a phenolic group as the donor undergo deprotonation and isomerization to form the corresponding quinone methides. This innovative strategy was applied to achieve (4 + 1)-annulation of cyclopropanes with sulfur ylides, affording functionalized dihydrobenzofurans. Additionally, the generated ortho - and para -(aza)quinone methides can be trapped by various CH-acids.