Selenium-containing phosphorus compounds

Series of selenium-containing phosphorus compounds (137-139) have been reported by Kimura and Murai. Phosphinoselenoic amides 137 were prepared from racemic phosphinoselenoic chlorides (138) and chiral amines and the individual isomers could be separated by column chromatography in some cases.Reaction of 137 with tributylphosphine afforded the P(III) aminophosphines with retention of configuration at the phosphorus atom. (5)-methylbenzylamine was also used to prepare both enantiomers of phosphinoselenoic chlorides 138 in 96% ee. In contrast to the oxygen analogues, they were found to be stable and could be purified by column chromatography. Several compounds, such as 139 for example, were prepared by stereoselective nucleophilic substitutions of the Cl atom. ... 

Phosphorus selenides and any compound which can evolve selenium on heating are very toxic. Any phosphorus compound containing toxic metals such as Be, Se, Cd, Hg or Pb (whether a direct metal-phosphorus linkages are present or not), should be regarded as potentially toxic. 

The neighboring group effect becomes particularly apparent within the SaS series relative to the oxidation of a simple sulfide. The generally lower oxidation potentials for the selenium- and phosphorus-containing compounds not only prove participation of these heteroatoms but also reflect their lower ionization potentials compared with sulfur. As discussed before, the best orbital overlap for formation of the 2(r/l(r three-electron bond is obtained for the five-membered ring (n = 3), evidenced by the lowest oxidation potentials and the most blue-shifted absorptions. (Remember that absolute optical transition energies may... 

The aim of this Report is to review new methodology for the synthesis of saturated heterocyclic compounds. Emphasis is placed on reactions which involve a cyclization step and few ring transformations are described. Heterocycles which contain phosphorus, selenium, and silicon as the heteroatom are omitted. A few key steps in complex natural product syntheses are mentioned, but carbohydrates are excluded. The rapidly increasing numbers of reports describing the synthesis of saturated and unsaturated lactones and of crown ethers are covered in Chapters 3 and 10. 

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