Palladium/Lewis Acid Cocatalyzed Ring-Opening Reactions of Unsymmetrical Oxabenzonobornadienes with Oximes.

The palladium/Lewis acid cocatalyzed ring-opening reaction of various C-substituted unsymmetrical oxabenzonorbornadienes (OBD) with oxime nucleophiles was investigated. The effects of various C substituents were explored. Moderate to excellent yields and excellent regioselectivities were obtained for electron-withdrawing groups. The presence of electron-donating alkyl groups leads to isomerization of the corresponding OBD to afford the substituted naphthol derivatives. Additionally, a mechanism for the formation of C regioisomeric ring-opened products has been proposed.