3-(6-Methyl-2-pyridyl)-2-phenyl-3,4-dihydro-1,3,2-benzoxazaphosphinine 2-oxide

Abstract

In the title compound, C19H17N2O2P, the six-membered 1,3,2-oxaza­phosphinine 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 inter­molecular hydrogen bonds. The phosphoryl O atom participates in inter­molecular C—H⋯O inter­actions with the neighbouring mol­ecules, forming centrosymmetric R 2 2(14) dimers.

Stacked Naphthyls and Weak Hydrogen-Bond Interactions Govern the Conformational Behavior of P-Resolved Cyclic Phosphonamides: A Combined Experimental and Computational Study

“…The two sp2 carbon atoms are shared with the adjacent naphthyl group and the oxygen lies approximately in the plane of the three carbon atoms of the cycle: the measured dihedral angles between the plane of these carbon atoms and the reference plane of the oxygen atom (angle between the two planes C–C–C and C–C–O) are in the range 3°–5° in all cases ( 1b – 4b) . The phosphorus and nitrogen atoms force the ring into a twist-boat conformation, which is reported elsewhere for related cyclic phosphonamides. , These structural features are evident in the prototype cyclic phosphonamide 1b depicted in Figure as a representative example.…”

“…The phosphorus and nitrogen atoms force the ring into a twist-boat conformation, which is reported elsewhere for related cyclic phosphonamides. 24,25 These structural features are evident in the prototype cyclic phosphonamide 1b depicted in Figure 1 as a representative example. The (S P ) configuration in the twist-boat conformation of the cyclic phosphonamide ring is characterized by axial and equatorial positions of the phosphonic oxygen and chloromethyl group, respectively (Figure 1).…”