Abstract Dimethylphosphoramides react with m-chloroperoxybenzoic acid (MCPBA) in anhydrous acetone to yield the previously unknown P-dimdethylamino-oxyphosphonous derivatives via N-oxidation and rearrangement. Further MCPBA oxidation yields formaldehyde and nitrosomethane, isolated as its trans-dimer. These reactions provide a possible biomimetic model for the metabolic activation of hexamethylphosphoramide as a ...