Remarkable Catalytic Activity of Sodium-Modified-Hydroxyapatite in the Synthesis of α-Hydroxyphosphonates

A green protocol for the synthesis of α-hydroxyphosphonates by condensation of carbonyl compounds on dialkylphosphites, under solvent free conditions, has been described using hydroxyapatite (HAP) catalysts. This condensation proceeds with excellent yields and 100% atom economy. The best results were obtained using Na-modified-hydroxyapatite (Na-HAP) catalyst. Furthermore, being heterogeneous in nature, these catalysts are easily separated from the reaction mixture and reused several times without any loss of activity, especially for Na-HAP, after being washed by acetone and calcined at 700°C.