Theoretical prediction of ³¹P NMR chemical shifts of intermediates in phosphoryl ester exchange and N → O migration reactions of dialkyloxyphosphoryl amino acid

Based on a detailed ab initio study on the reaction mechanism of phosphoryl ester exchange and N → O migration reactions of dimethyloxyphosphoryl-threonine, ab initio GIAO magnetic shielding calculations have been carried out on the predicted stable intermediate and the corresponding reactant and product. The ³¹P NMR chemical shift of the most stable penta-coordinate phosphorus intermediate has been predicted as about -71 ppm. The theoretical results may lead to a possible way to experimentally examine our predictions and to monitor the most stable intermediate during the reaction process.