Three improved thiophosphoroselenenylation procedures of CH-acids, including derivatives of malonic and acetyl-, phosphono-, 4-nitrophenyl- and 3-pyridylacetic acids, have been described and compared to previously reported thiophosphoroselenylation of diethyl malonate using bis(disopropoxyphosphinothioyl)diselenide alone or with the aid of methyl iodide. The use of iodine makes it possible to utilize both equivalents of the selenenylating agent. The procedures work well for the majority of

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... ophiles in a pKa range between more acidic malononitrile or Meldrum acid and less acidic phenylacetates. The reaction carried out on diethyl malonate in boiling rectified ethanol yields selenoacetate, which cannot be obtained by direct phosphoroselenenylation. Crystal structure of one of the selenomalonamides confirms the stabilization effects of both carbonyl oxygens on selenium atom. The P-Se bond splitting, using TBAF in 3-molar excess in the presence of alkylating agent yields the respective C,Se-dialkyl derivatives.