Efficient Selenenylation of Malonates Using Bis(phosphorothioyl) Diselenide

Abstract

Bis(O,O-diisopropoxyphosphinothioyl) diselenide reacts readily and quickly with the sodium salt of malonates to give quantitatively stable sodium 2-(O,O-diisopropyl phosphorothioselenenyl)propanedioates. No traces of the corresponding C,C-diselenenylation products were detected. A standard aqueous workup procedure affords the products, albeit in poor yield (about 45%). It was proved that the reaction is reversible due to the presence of nucleophilic sodium O,O-diisopropylphosphoroselenothioate in the reaction mixture. The reaction conducted with methyl iodide as a coreactant significantly improved the yield of the selenenylated product up to 88%. In contrast to the respective C-(phenylselenenyl)malonate that undergoes thermal disproportionation, the diethyl 2-(O,O-diisopropyl phosphorothioselenenyl)propanedioate is stable and remains unchanged even after prolonged heating in boiling toluene. The mechanism of phosphorothioselenenylation of malonates is described.

GRAPHICAL ABSTRACT

Keywords:

• C-nucleophiles
• electrophilic diselenides
• phosphorothioselenoic acid Se-esters
• selenenylation