Phosphorus-carbon bond cleavage process

Instability in the supposedly stable phosphorus-carbon bond displays itself not only in unfortunate ways, leading as it does to side reactions and the formation, in synthesis, of unwanted by-products, but also in a constructive manner, forming the basis of reaction sequences of outstanding value in synthesis, as for example in alkene-forming reactions. Instability is an inherent property of (a-hydroxyalkyl)phosphonic acids which manifests itself in phosphorus-carbon bond cleavage as a result of the action of heat or of alkali, and which can lead either to dissociation into precursors or to rearrangement to phosphates (a-oxoalkyl)phosphonic derivatives are susceptible to attack by nucleophiles, a process which also results in carbon-phosphorus bond fission. 

Earlier suggestions of stereoelectronic control of acetal cleavage for the lysozyme reaction Gorenstein, D. G., Findlay, J. B., Luxon, B. A., Kar, D. (1977). Stereoelectronic control in carbon-oxygen and phosphorus-oxygen bond breaking processes. Ah initio calculations and speculations on the mechanism of action of ribonuclease A, staphylococcal nuclease, and lysozyme. Journal of the American Chemical Society, 99, 3477. 

The orthometallation process and the possibility of stabilizing fragments RP by bonding to the metal framework make this oxidative addition with cleavage of the strong phosphorus-carbon bond possible. 

The A2 mechanism which has been thought to describe the acid-catalysed hydrolysis of methyl methylarylphosphinate esters, ArMeP(0)OMe, has been confirmed by bond fission studies. However, some 10% of reaction involves carbon-oxygen and not phosphorus-oxygen cleavage, so another pathway is in competition with the main process. The hydrolysis of aryl dimethylphosphinates, Me2P(0)0Ar, is catalysed by nucleophiles. 

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