3-(6-Methyl-2-pyrid-yl)-2-phenyl-3,4-dihydro-1,3,2-benzoxaza-phosphinine 2-oxide.

In the title compound, C(19)H(17)N(2)O(2)P, the six-membered 1,3,2-oxaza-phosphinine ring adopts a boat conformation with the phosphoryl O atom in an equatorial position. The dihedral angle between the 6-methyl-2-pyridyl and phenyl groups is 75.5†(1)°. These substituents are trans to each other, and are oriented at angles of 57.2†(1) and 74.8†(1)°, respectively, to the benzene ring. The crystal structure is stabilized by intra- and inter-molecular hydrogen bonds. The phosphoryl O atom participates in inter-molecular C-H⋯O inter-actions with the neighbouring mol-ecules, forming centrosymmetric R(2) (2)(14) dimers.