7a-Phenyltetrahydropyrrolo[2,1-b]oxazol-5(6H)-one

In the crystal of the title compound, C—H⋯O and C—H⋯π contacts link the molecules into infinite chains directed along the b-axis direction.

In contrast to closely related pyrrolopyrimidinones (Grinev et al., 2020), there is no classical hydrogen bonding in the crystal of the title molecule, obviously due to the data reports absence of NH groups (Fig. 2). The molecules are connected via weak C5-H5AÁ Á ÁO2 links (Table 1) to generate infinite chains directed along [010]. The H5AÁ Á ÁO2 distance of 2.58 Å is significantly longer than the corresponding distance in pyrrolopyrimidinones [2.28 (5)-2.306 (18) Å ]. Moreover, there are C10-H10Á Á Á contacts to an adjacent phenyl ring (Fig. 3), which reinforce the [010] chains.

Figure 1
The molecular structure of the title compound showing 50% displacement ellipsoids.
being left to stand overnight, the separated crystals and precipitate were washed with benzene and acetone and the solid placed in a vacuum desiccator for drying (yield 0.91 g, 75%; m.p. 65-67 C). The single crystal used for data collection was obtained directly from the cooled reaction mixture.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.

Funding information
Funding for this research was provided by: Russian Foundation for Basic  to Alevtina Yu. Yegorova).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.