The structures of two compounds, 3-[1-(2-hydroxyethyl-amino)ethylidene]-2-m
ethoxy-3,4-dihydro-1,2 lambda (5)-benzoxaphosphinane-2,4-dione, C13H16NO5P,
and 3-[1-(2-hydroxyethylamino)ethylidene]-2-methoxy-6-methyl-3,4-dihydro-
1,2 lambda (5) -benzoxaphosphinane-2,4-dione, C14H18NO5P, have been studied
and compared. The oxophosphinane rings have a half-chair conformation and
extra six- and five-membered rings are formed by intramolecular N-H . . .O
hydrogen bonds. An intermolecular O-H . . .O hydrogen bond is also observed
.