Chalcogenide ylides

Density functional theory has been used to calculate the P-E bond energies and orbital populations of trimethylphosphine chalcogenides and related compounds. The results indicate that Me3P=CH2 has a 7i-bond order of 0.5. The equilibrium acidities in DMSO solution and gas-phase homolytic bond dissociation energies of tributylphosphonium ylide precursors have also been determined. ... 

Vinyl sulfides, selenides, and tellurides are prepared in a one-pot procedure by treating mixtures of the chloromethyl phenyl chalcogenide and triphenylphosphine in THF with /-BuOK (to form the ylide), followed by the addition of a carbonyl compound (eq 95). The yields are good to poor and the Z isomer is usually favored. 

The chemistry of phosphine chalcogenides, phosphonium salts and ylides has also continued to develop and activity in this area remains at a high level. Of note is a growing literature on the use of phosphonium-based ionic liquids as solvents. 

Phosphine chalcogenides Phosphonium salts Ylides (phosphoranes)... 

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