Monophosphorylation of ethylenediamine with systems generating low-coordination phosphoryl species

Phenyldioxophosphorane was generated by thermal fragmentation of N-(1-adamantyl)phenylphosphonamidic acid in ethylenediamine to give a 61% yield of N-(2-aminoethyl)phenylphosphonamidic acid. The zwitterionic structure repressed reaction of the other amino group. Neopentyl metaphosphate and ethyl metaphosphate were generated in the presence of ethylenediamine by heating appropriate derivatives of the 2,3-oxaphosphabicyclo2.2.2]octene system in toluene. Again, the metaphosphate phosphorylated only one amino group to give O-alkyl N-(2-amino-ethyl)phosphoramidic acids, in zwitterionic form. © 1996 John Wiley & Sons, Inc.