Reaction of sodium N-benzylideneglycinate with dialkyl chlorophosphites in the presence of water

The outcome of reaction of sodium N-benzylideneglycinate containing water in its crystal lattice with dialkyl chlorophosphites depends on the mode of addition of the latter. Upon the simultaneous mixing of the reactants, 1,4-bis[α-(dialkoxyphosphoryl)benzyl]piperazine-2,5-diones are formed from two molecules of each reactant. With the slow addition of dialkyl chlorophosphite, the main reaction product is 2-{3-[α-(dialkoxyphosphoryl)benzyl]-5-oxo-2-phenylimidazolidin-1-yl}acetic acid (‘1: 2 adduct’), its formation comprising 1,4-migration of dialkoxyphosphoryl moiety.