Polymers containing formamidine groups, 5 Formation of a cyclic formamidine trimer by the condensation reaction of 2,6‐diaminopyridine with triethyl orthoformate

The condensation reactions of the structurally similar monomers 1,3‐phenylenediamine (1a) and 2,6‐diaminopyridine (1b) with triethyl orthoformate have been compared. Whereas the reaction of 1a resulted in an oligomeric polyformamide, a cyclic trimer was obtained almost quantitatively when monomer 1b was used. The structure of the trimer has been discussed with respect to results obtained by NMR and MALDI spectroscopy.