Alternative mild route to the synthesis of 4-methylenecyclohex-2-enone, a key moiety of the anticancer compounds ottelione A and B

Rare 4-methylenecyclohex-2-enone is prepared from a Diels-Alder methanesulfonate adduct and sodium iodide in acetone in up to 70% yield under mild conditions. This procedure is envisaged to be relevant to the synthesis of 4-methylenecyclo hex-2-enone analogues, structurally similar to the key functionality of cytotoxic otteliones and with potentially significant bioactivity.