Enantio‐ and Diastereoselective Synthesis of <i>exo</i>‐Peroxyacetals: An Organocatalyzed Peroxyhemiacetalization/oxa‐Michael Addition Cascade

Abstract

An unprecedented enantioselective peroxyhemiacetalization/oxa-Michael addition cascade of ortho-formyl homochalcones has been developed using cinchona-alkaloid-based chiral bifunctional organocatalysts to provide cis-configured exo-peroxyacetals, a new class of organic peroxide, in good yields with excellent enantio- and diastereoselectivities. The resulting cis-configured exo-peroxyacetals were converted into the corresponding trans-configured peroxyacetals without affecting the enantioselectivity. Furthermore, the displacement of the peroxide moiety of exo-peroxyacetals with various nucleophiles has been demonstrated to afford 1,3-disubstituted isochromans with high diastereoselectivities and excellent enantioselectivities.