Aerobic Dimerization of Enediyne Compounds: Construction of Naphthalene Frameworks

The first bimolecular oxygenative annulation of enediyne compounds leading to naphthalene frameworks has been developed by using Pd(OAc)(2) as the catalyst in the presence of NaI under O-2 (1 atm). This reaction provided efficient access to a class of symmetric core-annulated naphthalenes by the homoannulation of enediyne-imides. Intriguingly, the crossover annulation of enediyne-imides and other functionalized enediynes could also be achieved by the same catalytic system, resulting in the formation of several unsymmetrical naphthalene derivatives. Preliminary mechanistic investigation using O-18 isotopic labelling and radical scavengers indicated that radical oxygen incorporation cascades might be involved in this conversion.