Synthesis of new malonaldehyde derivatives using 2-heteroaryl-substituted trimethinium salts

A synthetic route for obtaining 2-heteroaryl-substituted zwitterionic malonaldehydes 1c–6c is described. The synthesis involves the two-fold formylation of heteroarylacetic acids 1a–6a using the Vilsmeier–Haack reagent, followed by hydrolysis of the intermediate trimethinium salts 1b–6b with aqueous sodium carbonate. Elemental analysis, IR, 1H NMR, 13C NMR, and mass spectral data confirm the structures of the newly synthesized compounds.