Rhenium-catalyzed synthesis of naphthalene derivatives via insertion of aldehydes into a C–H bond

A rhenium complex, [ReBr(CO)3(THF)]2, catalyzed reactions of aromatic ketimines and aldehydes with dienophiles, followed by dehydration, to give naphthalene derivatives in good to excellent yields. This reaction proceeds via C–H bond activation, insertion of an aldehyde, intramolecular nucleophilic cyclization, reductive elimination, elimination of aniline and Diels–Alder reaction. After dehydration, naphthalene derivatives were formed.