Alkaline hydrolysis of aryl phosphoramidates and their cyclic analogues

Abstract

The products of alkaline hydrolysis of the title compounds have been determined and their rates of formation measured. While the acyclic compounds react slowly to give products derived exclusively from loss of phenolate ion, the cyclic compounds react ca. 10⁴ times faster to give more complex mixtures of products. In the case of N-alkyl derivatives, small amounts of cyclic P–N and P–O bond cleavage are observed in addition to cleavage of the P–O aryl bond, whereas in the case of the N-aryl derivatives, loss of phenolate ion is accompanied by significant amounts of cyclic P–O cleavage, with no detectable P–N bond cleavage. These results are interpreted in terms of trigonal bipyramidal intermediates, which in the case of the N-methyl cyclic compounds may undergo protonation at nitrogen, even in the basic medium employed in their formation.