Investigations on benz[1,2]oxaphosphinane derivatives

The structures of two compounds, 3-[1-(2-hydroxyethylamino)ethylidene]-2-methoxy-3,4-dihydro-1,2lambda(5)-benzoxaphosphinane-2,4-dione, C(13)H(16)NO(5)P, and 3-[1-(2-hydroxy-ethylamino)ethylidene]-2-methoxy-6-methyl-3,4-dihydro-1,2lambda(5)-benzoxaphosphinane-2,4-dione, C(14)H(18)NO(5)P, 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.