Copper(II)-dipicolinate-mediated clickable azide–alkyne cycloaddition in water as solvent

A contribution dedicated to our friend Prof J. Faus in recognition of his outstanding career.

Abstract

Copper(II)-dipicolinate complex [Cu^II(dipic)(H₂O)₂] (1) (H₂L = dipicolinic acid (H₂dipic)) was synthesized via oxidation of copper(I) iodide and pyridine-2,6-dicarboxylic acid in water and acetonitrile in the presence of glycine. Complex 1 was characterized by FT-IR and elemental analysis and its structure confirmed by single crystal X-ray analysis. This complex is an efficient precatalyst that mediates azide–alkyne cycloaddition reactions in water at room temperature either in the absence or presence of a reducing agent. Compound 1-mediated azide–alkyne cycloaddition affords alkyl/aryl substituted 1,2,3-triazole heterocycles in a regioselective manner and excellent yields under very mild reaction conditions matching the criteria of greener protocols.

Keywords:

• Dipicolinic acid
• copper
• homogenous catalysis
• click chemistry
• azide–alkyne cycloaddition
• 1,2,3-Triazoles

Acknowledgements

We are grateful to the Spanish Ministerio Español de Ciencia e Innovación (Project CTQ2016-75068P), the Generalitat Valenciana (PROMETEO/2014/070), the Université Cadi Ayyad (UCAM) the Centre National de la Recherche Scientifique (CNRS) and the Brest University.

Notes

A contribution dedicated to our friend Prof J. Faus in recognition of his outstanding career.