1,4-Diionic organophosphorus compounds: Stereoselective synthesis of dialkyl 2-(1,1,1,5,5,5-hexafluoro-2,4-dioxo-pentane-3-yl-3-yide)-3-triphenylphosphoniobutane-1,4-dioates

The addition of triphenylphosphine to dialkyl acetylenedicarboxylates in the presence of 1,1,1,5,5,5-hexafluoropentane-2,4-dione leading to highly functionalized 1,4-diionic organophosphorus compounds is reported. These stable crystalline phosphorus betaines were characterized by spectroscopy, mass spectrometry and elemental analysis.