Total Synthesis of Dysidiolide

The cdc25A protein phosphatase inhibitor dysidiolide ( 1 ) has been synthesized enantioselectively, starting from the enantiomerically pure ketal enone 2 and using a cationic rearrangement as the key step to produce the fully substituted bicyclic core of the natural product. Once the central portion of 1 was established, elaboration of the side chains was accomplished expediently via steps that included (1) vinyl cuprate displacement of an iodide to complete the C-1 side chain, (2) a highly diastereoselective oxazaborolidine-catalyzed (CBS) reduction to form carbinol 11, and (3) photochemical oxidation of 11 to generate the γ-hydroxybutenolide functionality of 1 . Additionally, this synthesis proves the absolute stereochemistry of dysidiolide ( 1 ).