New zinc catalysts based on easy-to-handle N4-chelating ligands for the coupling reaction of epoxides with CO2

• Zinc complexes based on N,N′-bis(2-pyridinecarboxamide)-1,2-benzene are air-stable.
• The zinc–N4 complexes need an ionic cocatalyst to form cyclic carbonates.
• The zinc-N4/TBAI system efficiently catalyzes the carboxylation of terminal epoxides.
• Substitution at the aromatic linker in N4-ligands influences the catalytic activity.

In this contribution, we report the successful utilization of several zinc complexes based on the N4–N,N-bis(2-pyridinecarboxamide)-1,2-benzene chelating ligand (and some of its variations) as catalysts in the coupling of epoxides with carbon dioxide to afford cyclic carbonates in good yields. The complexes were tested with cyclohexene oxide and propylene oxide. A broader catalytic screening involving several commercial available epoxides was also carried out with a selected catalyst.

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