Practical Synthesis Of 4-Pyridyl Phosphonates

Abstract

Pyridyl phosphonates are valuable motifs in medicinal chemistry, catalysis, and materials science. Common routes for their synthesis often rely on prefunctionalized pyridines, transition-metal-catalyzed cross-coupling reactions, special free radical conditions or photochemical reactions. Herein, we report a mild, one-pot, and regioselective method to access 4-pyridyl phosphonates from simple pyridines via chloroformate-mediated pyridine activation, nucleophilic phosphite addition, and oxidative rearomatization using molecular oxygen. The method shows broad tolerance toward 3-substituted pyridines, while challenges associated with 2-substitution were addressed through a complementary post-functionalization strategy enabling access to 2-substituted pyridyl phosphonate scaffolds.