Visible light–driven stereodivergent allylation of cyclic hemiacetals with butene for polypropionate synthesis

Catalytically transforming abundant hydrocarbon feedstocks into structurally complex, high-value molecules is a pivotal yet challenging goal in organic synthesis. The key difficulty lies in the simultaneous activation of chemically inert feedstocks and precise stereochemical control. Here, we report a catalytic stereodivergent allylation of unprotected cyclic hemiacetal aldols with butene, enabling the programmable synthesis of polypropionates-privileged structural motifs prevalent in biologically active compounds, including pharmaceuticals. This visible light-driven, selective transformation exhibits broad functional group compatibility, furnishing 1,3-polyols with multiple contiguous stereocenters in high yield and stereochemical fidelity. Moreover, this method provides a concise and practical route to key natural product intermediates with minimal protection-deprotection sequences. This strategy has the potential to streamline polypropionate synthesis while reducing the time, cost, and environmental impact.