Variation in conformation and weak intermolecular interaction networks of substituted 3-benzyl-2-phenyl-1,3,2-oxazaphospholidin-2-ones

The crystal structures of three 3-benzyl-2-phenyl-1,3,2-oxazaphospholidin-2-one derivatives have been determined by X-ray diffraction. Synthesis of compound (I), a racemic mixture of (2S) and (2R)-3-benzyl-2-phenyl-1,3,2-oxazaphospholidin-2-one, compound (II), (2S,4S)-3-benzyl-2-phenyl-4-(propan-2-yl)-1,3,2-oxazaphospholidin-2-one and compound (III), a mixture of (2S,4S) and (2R,4S)-3,4-dibenzyl-2-phenyl-1,3,2-oxazaphospholidin-2-one were easily carried out starting from the corresponding N-protected amino alcohols and phenyl-phosphonic dichloride. Crystal structure of (I) and (III) exhibit monoclinic symmetries as (II) exhibits orthorhombic symmetry. Their packings are ensured by a combination of different types of weak non-covalent and competitives effects, in particular, π/π stacking against CH/π hydrogen bonds. The significance of this study lies in the comparison drawn between these crystal structures and those of several of its simple analogues.