Phospholide Ions General Data

In many respects there is a continuum between the synthesis and chemistry of phospholide ions and of phosphametallocenes. Additionally, most syntheses of phosphametallocenes start from phospholide ions, so a quick glance at their chemistry is desirable. 

The first and still most widely employed synthesis of phospholides rests on the cleavage of the exocyclic P-Ph bond of 1-phenylphospholes by alkali metals (Eq. 1) [5]  

Alternatively, strong bases are able to cleave selectively activated P-alkyl bonds as shown in (Eq. 2) [9]  

The mechanism involves a proton abstraction from the carbon atom bearing the electron-withdrawing group Z. 

A third approach takes advantage of [l,5]-sigmatropic shifts of sp- or sp2-hy-bridized carbon substituents from phosphorus to the a-carbons of the ring. These occur upon heating. The transient 2H-phosphole products can be depro-tonated by a base (Eq. 3) [10]  

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