Studies aimed at the development of new synthetic pathways for the preparat
ion of chiral cyclic oxaza and diaza phosphoramides suitable for use in asy
mmetric chemistry led us to the investigation of the imide-amide rearrangem
ent of cyclic phosphorimidates. As a result of this work new types of oligo
meric organophosphorus compounds, formed by a novel 1,4-addition type ring
opening polymerisation, were identified. These compounds are the stable int
ermediates of the imide-amide rearrangement, which upon heating yield the p
reviously reported rearranged product, A detailed study of the mechanism of
the Lewis acid catalysed imide-amide rearrangement and stereochemical cont
rol of the final products is reported. As a result, the full mechanism was
elucidated and evidence of retention of configuration at the rearranged car
bon atom is presented. Substituent effects were rationalised based on molec
ular modelling calculations.