Practical Synthesis of New β‐Diketone‐Connected Bipyridine and Its Conversion to Pyrazole‐Centered Bipyridine Ligand

Abstract

Two new polydentate ligands, 1‐(6‐hydroxymethyl‐2‐pyridyl)‐3‐(2‐pyridyl)‐propane‐1,3‐dione (6) and 1,3‐bis(6‐hydroxymethyl‐2‐pyridyl)‐propane‐1, 3‐dione (8), have been synthesized starting from 2,6‐pyridinedicarboxylic acid by conventional esterification, reduction, and condensation reactions. They were further converted to two new polydentate ligands, 3‐(6‐hydroxymethyl‐2‐pyridyl)‐5‐(2‐pyridyl)‐1H‐pyrazole (7) and 3,5‐bis(6‐hydroxymethyl‐2‐pyridyl)‐1H‐pyrazole (9), by reaction with hydrazine hydrate. These four compounds were characterized by proton nuclear magnetic resonance (¹H NMR), electrospray ionization‐mass spectrum (ESI‐MS), infrared spectrum (IR), and elemental analyses. The structure of 9 was also determined by X‐ray diffraction.

Keywords:

• crystal structure
• polydentate ligands
• pyrazole derivatives
• synthesis

Acknowledgments

The authors are grateful to the Natural Science Foundation of China (No. 20128005 and 20672017), the Swedish Energy Agency, and the Swedish Research Council for financial support.