Abstract

   Selectivity control of C=C double bond especially in those tetrasubstituted olefins is a fundamental issue in organic chemistry due to their importance in organic chemistry, medicinal chemistry, and material chemistry. Herein, we observed that the stereoselectivity of chlorosulfonylation of allenoic acids or allenoates has been reversed by applying an organic photo-catalyst in combination with a copper catalyst of Cu(acac)₂ affording Z-selective tetrasubstituted olefins substituted with a heteroatom of sulfur. The reaction tolerates a broad range of functional groups. In addition, the intermediate trapping experiment and the reaction of optically active allenoate have confirmed the presence of sulfonyl and allylic radicals. Cyclic voltammetry studies and Stern-Volmer quenching experiments have demonstrated that the reaction proceeds via oxidative quenching mechanism. Cu(acac)₂ was found to perform a crucial role through the formation of stereo-defined Π-allyl Cu species in the stereo-selective chlorosulfonylation.

Yaqi Shi (史亚琪)