Studies toward the total synthesis of axinellamine and massadine

Intramolecular Diels-Alder reactions of several N-O linked 4-vinylimidazole dimers provide the expected adduct in moderate to good yield as a single, all trans stereoisomer, along with smaller amounts of the inverse electron demand adduct. Oxidative rearrangement of the cycloadducts occurs on treatment with Davis' reagent, providing a single spiro imidazolone in good yield and with excellent levels of stereocontrol albeit epimeric at the spiro center found in axinellamine and massadine.