Sulfur-Directed Construction of Vinyl Cyclopropanes from 1,3-Dienes

The stereoselective cyclopropanation of 1,3-dienes remains a long-standing challenge in the preparation of vinyl cyclopropanes (VCPs) due to the intrinsic electronic and steric bias of the diene scaffold. We report a sulfur-directed strategy that enables highly site- and diastereoselective cyclopropanation of S-substituted 1,3-dienes with diazo reagents under Cu-catalyzed reaction conditions. This unprecedented approach overrides the innate reactivity of the 1,3-diene through a thioether-directed reaction mode, providing rapid access to a broad library of highly functionalized S-VCPs obtained as single regio- and diastereomers. Preliminary mechanistic studies indicate a pericyclic cascade involving a 6π-electrocyclization and a [2,3]-sigmatropic rearrangement and postmodifications permit streamlined access to complex VCPs that remain inaccessible through conventional cyclopropanation techniques.