The Addition of Dialkyl Phosphites and Diphenylphosphine Oxide on the Triple Bond of Dimethyl Acetylenedicarboxylate under Solvent-Free and Microwave Conditions

Abstract

The addition of dialkyl phosphites or diphenylphosphine oxide to the triple bond of dialkyl acetylenedicarboxylate may result in mono- and/or bisadducts. The ratio of the products may be influenced by the molar ratio of the reactants and the conditions (temperature of microwave irradiation and reaction time). Stereospecific <sup>3</sup>J<sub>PP</sub> couplings were utilized in the assignments to the meso and racemic forms of the bisadducts. The bis(dialkylphosphonyl)-succinates were formed as a mixture of the corresponding meso form and racemate, while bis(diphenylphosphinoyl)-succinate was obtained as a racemate. The <sup>31</sup>P–<sup>12</sup>CH–<sup>13</sup>CH–<sup>31</sup>P spin system of bis(dialkylphosphonyl)-succinates was subjected to a detailed NMR analysis supported by simulation.