Atom-economic thiophosphoroselenenylations of C–H acid esters and amides

Abstract

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 nucleophiles 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.

Graphical Abstract

Keywords:

• C–H methylene compounds
• selenenylation
• thiophosphoryl protective group

Acknowledgements

The authors wish to thank Professor J. Chojnacki, Department of Inorganic Chemistry, Gdansk University of Technology, for the X-ray diffraction analysis of 3l.

Additional information

Funding

This work was supported by the Ministry of Science and Higher Education under Grant number NN204372040.