Dephosphonylation reaction

The hydrolysis of a monoalkyl phosphate may also be classed as a dephosphonylation reaction, that is, one involving removal of the O-phosphono [(HO)gP(O)-] group.259... 

In work aimed at elucidating the mode of pyridoxal mediated dephosphonylation of a-aminophosphonic acids, it was found that simple aminophosphonates reacted with pyridoxal to form Schiff bases, which complexed copper(II) ions, but did not react further. In contrast, o-hydroxyphenylphosphaglycine did react with pyridoxal at 40 °C with the formation of pyridoxamine, along with o-hydroxybenzoylphosphonic acid on the one hand (equation 45), and salicylaldehyde and H3PO4 (not shown) on the other. Apparently, the presence of the -hydroxy group is necessary for the success of the reaction, presumably by complexing the copper ion in the fashion indicated. The formation of 6>-hydroxybenzoylphosphonic acid illustrates the capability of a-aminophosphonic acids to participate in transamination (similarly to amino acids), while salicylaldehyde is the result of dephosphonylation (analogous to decarboxylation). 

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