Reaction of some strong N-bases with chloropentafluorobenzene in the presence of water molecules.

Products of reactions between chloropentafluorobenzene and strong N-bases (DBN, DBU, TBD, and MTBD) in polar aprotic solvents and in the presence of water were isolated and identified by analytical and spectroscopic methods. The products of these dehydrohalogenation reactions are apropriate lactams, and if the TBD N-base is used, a condensation occurs with formation of benzimidazole derivative. All the products are not formed directly in the nucleophilic substitution by N-bases but after the hydrolyses of the N-bases with formation of amines known as hard nucleophiles.