Catalytic activity of chelating N-heterocyclic carbene palladium complexes towards selective phosphorylation of coumarins

•The catalytic activity of a series of heteroaryl coordinated chelating NHC palladium complexes towards the phosphorylation of coumarins was presented.•The chelating NHC palladium complex bearing the most σ-donating backbone and a more rigid five-membered chelating ring showed the highest efficiency.•Optimized conditions: AgNO3 as oxidant, CH3CN as solvent, 80 °C.•The system showed high catalytic activity and wide functional group tolerance.

The catalytic activity of a series of heteroaryl coordinated chelating N-heterocyclic carbene (NHC) palladium complexes bearing different N-substituents, NHC backbones and chelating rings towards the phosphorylation of coumarins, and the relationship between the activity and the structure are presented. The results showed that the chelating NHC palladium complex Ia–b bearing the most σ-donating backbone and a more rigid five-membered chelating ring showed the highest efficiency. Using AgNO3 as oxidant, a wide range of coumarins reacted with different dialkyl phosphite or diphenylphosphine oxide smoothly in CH3CN, producing the target product in moderate to high yields.

Graphical abstractThe catalytic activity of a series of heteroaryl coordinated chelating N-heterocyclic carbene (NHC) palladium complexes bearing different N-substituents, NHC backbones and chelating rings towards the phosphorylation of coumarins, and the relationship between the activity and the structure are presented.Figure optionsDownload full-size imageDownload as PowerPoint slide