Amidoalkylation of hydrophosphoryl compounds

A new mild procedure of the amidoalkylation of hydrophosphoryl compounds in a mixture of acetic anhydride and acetyl chloride was developed as a convenient method of constructing the α-aminophosphoryl fragment of the pseudo-α,α′-dipeptide molecule. The reaction intermediates N,N′-benzylidene- and N,N′-alkylidenebiscarbamates were detected, isolated, and identified. The report presents the results of studying the direct interaction of hydrophosphoryl compounds previously synthesized with biscarbamates in acetic anhydride and other solvents, the influence of the structure of phosphorus component and biscarbamate, and the effect of acid catalysis on the course of this two-component reaction. A new version of the mechanism of the three-component reaction of amidoalkylation of hydrophosphoryl compounds is suggested: it is regarded as a multistage process involving the stage of biscarbamate formation followed by the stage of Arbuzov-type reaction with the intermediate formation of acyliminium cation and P-OAc derivative with trivalent phosphorus.