An unexpected result in an intramolecular Ritter reaction induced by triflic anhydride

The treatment of the methyl 2-(cyanoethyl)-1-hydroxy-2-indane-carboxylate 1b in dichloromethane solution with triflic anhydride at 20°C afforded the tricyclic enone 3 in 65% yield, instead of the expected lactam 2b produced under the ‘classic’ conditions of the Ritter reaction.