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Phosphinooxazolines (often abbreviated PHOX) are a class of chiral ligands used in asymmetric catalysis. Their complexes are particularly effective at generating single enatiomers in reactions involving highly symmetric transition states, such as allylic substitutions, which are typically difficult to perform stereoselectively. The ligands are bidentate and have been shown to be hemilabile with the softer P‑donor being more firmly bound than the harder N‑donor. ==Synthesis== The synthesis of phosphinooxazolines is modular and it is not normally necessary to introduce the phosphine and oxazoline moieties in any particular order. However while examples exist of the phosphine being introduced first, it is more common to see the synthesis of a phenyloxazoline which is subsequently combined with a source of diphenylphosphine. Methods for doing this depend on the nature of the subsituent in the X position: * When X = fluorine coupling involves anionic displacement with a diphenylphosphine anion * When X = bromine this can be converted into a Grignard reagent and reacted with chlorodiphenylphosphine, or coupled with diphenylphosphine via a copper iodide catalysed reaction. * When X = hydrogen this undergoes directed ortho lithiation (facilitated by intramolecular coordination with the oxazoline) followed by reaction with chlorodiphenylphosphine Of these methods the copper iodide catalysed reaction method is by far the simplest to carry out, as it does not require the synthesis of discrete anionic or organometallic species and is able to couple a wide range of materials in good to excellent yields. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Phosphinooxazolines」の詳細全文を読む スポンサード リンク
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