Copper–cobalt double metal cyanides as green catalysts for phosphoramidate synthesis

Abstract

Phosphoramidates are common and widespread backbones of a great variety of fine chemicals, pharmaceuticals, additives and natural products. Conventional approaches to their synthesis make use of toxic chlorinated reagents and intermediates, which are sought to be avoided at an industrial scale. Here we report the coupling of phosphites and amines promoted by a Cu3[Co(CN)6]2-based double metal cyanide heterogeneous catalyst using I2 as additive for the synthesis of phosphoramidates. This strategy successfully provides an efficient, environmentally friendly alternative to the synthesis of these valuable compounds in high yields and it is, to the best of our knowledge, the first heterogeneous approach to this protocol. While the detailed study of the catalyst structure and of the metal centers by PXRD, FTIR, EXAFS and XANES revealed changes in their coordination environment, the catalyst maintained its high activity for at least 5 consecutive iterations of the reaction. Preliminary mechanism studies suggest that the reaction proceeds by a continuous change in the oxidation state of the Cu metal, induced by a O2/I− redox cycle.

Preparation of Well-Defined Double-Metal Cyanide Catalysts for Propylene Oxide Polymerization and CO2 Copolymerization

“…Notwithstanding its six-decade-long history and industrial significance, the composition, structure, and working mechanism of the heterogeneous DMC catalyst are still elusive and require further elucidation to continue its progress and improvement. − Furthermore, DMC complexes hold promise beyond polyol production and have displayed potential applications in various fields of catalysis and materials science. − In this study, we have successfully synthesized well-defined DMC catalysts, shedding light on their chemical structure and establishing a correlation between structure and performance, ultimately, leading to the discovery of efficient catalysts for both PO polymerization and CO 2 copolymerization.…”