A new, practical, synthesis of pyruvic orthoesters relying on the conversion of β-substituted phosphoenol pyruvates by the action of alkoxides is described. Our study of the reaction mechanism was done experimentally and also theoretically. Density functional theory calculations were used to explain the major reaction products found experimentally. Geometry optimisations and atomic charges obtained using different population analyses and the global and local reactivity indices, namely global electrophilicity and the Parr function, were obtained at the B3LYP/6-311G(d) level of theory. The experimental reactivity was correctly reproduced using the Parr function.