One-Pot Regio- and Diastereoselective Gold-Catalyzed Propargylation of in Situ Activated Chromones and Consecutive Cyclization

Herein, we report a gold-catalyzed propargylation of
chromone derivatives
by propargylsilanes. Chromones are synergistically activated by the
silylium cation resulting from the gold activation of the propargylsilane.
The reaction exclusively occurs at the C2-position of the chromone,
and a single diastereoisomer is formed. Computational studies performed
on the reaction mechanism rationalize the formation of the preferred
diastereoisomer. Finally, a dual consecutive cascade reaction based
on different gold catalysts enables the formation of complex tricyclic
compounds.