The reactions of diethyl acylphosphonates (1a-e) with Yb and Sm were examined. Reactivities of Yb to 1a-e are different from those of Li and Na. Typically, ethyl benzoylphosphonate (1a) reacts with Yb metal in tetrahydrofuran-hexamethylphosphoramide to afford diethyl 1,2-diphenyl-2-oxoethyl phosphate (2a) and diethyl 1-(diethyl-phosphoryloxy)-1-phenylmethylphosphonate (3a). The formations of 2a and