Abstract: | The syntheses, X‐ray structural investigations and calculations of the conformational preferences of the carbonyl substituent with respect to the pyran ring have been carried out for the two title compounds, viz. C15H14N2O2, (II), and C20H16N2O2·C2H3N, (III), respectively. In both molecules, the heterocyclic ring adopts a flattened boat conformation. In (II), the carbonyl group and a double bond of the heterocyclic ring are syn, but in (III) they are anti. The carbonyl group forms a short contact with a methyl group H atom in (II). The dihedral angles between the pseudo‐axial phenyl substituent and the flat part of the pyran ring are 92.7 (1) and 93.2 (1)° in (II) and (III), respectively. In the crystal structure of (II), intermolecular N—H⋯N and N—H⋯O hydrogen bonds link the molecules into a sheet along the (103) plane, while in (III), they link the molecules into ribbons along the a axis. |