Total Synthesis of Dinorsesquiterpenoid Oxyphyllin A/Belchinoid A

Here, we report the first synthesis of oxyphyllin A/belchinoid A, a 7,9-seco-8,12-dinor-guaiane sesquiterpene whose isolation was reported independently by two groups in 2023. This synthesis utilizes a key sequential sulfone-mediated intermolecular alkylation/5-endo-tet cyclization reaction to establish the C1, C4, C5 stereocenters. Subsequent transformations, including regio- and stereoselective hydride addition-based desulfonylation via a π-allyl palladium complex and the Wittig reaction with a stable phosphonium ylide, facilitated the synthesis of oxyphyllin A/belchinoid A.