Alcohol-Triggered Asymmetric Cascades for Divergent Access to Chiral Oxaspirolactones and Tetrahydropyrans

We report an alcohol-triggered asymmetric cascade strategy that converts simple aldehyde-containing 1,5-dicarbonyl compounds to structurally diverse oxygen heterocycles. In this design, aldehyde-to-alcohol transformations, exemplified by Henry and allylation reactions, operate as versatile cascade-triggering events, enabling the in situ generation of cyclic hemiketal intermediates that provide divergent access to spiro-oxaspirolactones and tetrahydropyrans. The resulting transformation provides a broad substrate scope and excellent stereocontrol, affording a versatile entry for the asymmetric synthesis of oxygen-containing heterocycles.