Asymmetric annulation of 3-alkynylacrylaldehydes with styrene-type olefins by synergetic relay catalysis from AgOAc and chiral phosphoric acid.

Asymmetric annulation of 3-alkynylacrylaldehydes with 2-hydroxystyrenes has been studied and achieved by synergetic catalysis from AgOAc and chiral phosphoric acid, providing the corresponding multiring products with decent total yields and moderate to excellent enantioselectivities (up to 95% ee). The developed mild multibond-formation cascade reaction involves in situ generation of pyrylium intermediate by Ag(I)-catalyzed alkyne/carbonyl cycloisomerization, counteranion-directed asymmetric oxa [4 + 2]-cycloaddition, and intramolecular nucleophilic substitution.