Synthesis of 1,4,2-Diazaphospholidine-3,5-diones Using Na(OCP) as the "P" Source

A refined synthesis of 1,4,2-diazaphospholidine-3,5-dione derivatives was achieved through a cyclization reaction involving Na(OCP) and isocyanates. Na(OCP) was demonstrated to be a relatively stable and safe source of phosphorus, enabling the production of diverse 1,4,2-diazaphospholidine-3,5-dione derivatives with high yields. The reaction proceeds efficiently under catalyst-free and mild conditions. Both experimental findings and density functional theory calculations have elucidated that the process involves a crucial step of carbon monoxide elimination, which provides deeper insight into the reaction mechanism.