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).

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Described herein is a new synthetic route to pseudopterosin aglycone (3), a key intermediate for the synthesis of a group of antiinflammatory natural products including pseudopterosin A (1) and E (2). The pathway of synthesis starts with the abundant and inexpensive (S)-(-)-limonene and its long-known cyclic hydroboration product (4) and leads to the chiral hydroxy ketone 6. Conversion of 6 to 10 followed by a novel aromatic annulation produced 15 which underwent a highly diastereoselective cyclization to afford the protected pseudopterosin aglycone 16. The naturally occurring pseudopterosins such as 1 and 2 are readily available from this key intermediate.

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