2-Amino-4-(1-naphthyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile and 2-amino-7,7-dimethyl-4-(1-naphthyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile

Syntheses and X-ray structural investigations have been carried out for the two title compounds, C(20)H(16)N(2)O(2), (IIIa), and C(22)H(20)N(2)O(2), (IIIb). In (IIIa), the heterocyclic ring adopts a sofa conformation, while in (IIIb), the ring has a flattened boat conformation. In both molecules, the fused cyclohexenone ring adopts a sofa conformation. The dihedral angles between these two flat fragments are 3.5 (2) and 17.5 (2) degrees in (IIIa) and (IIIb), respectively. The dihedral angles between the pseudo-axial naphthalene substituents and the planes of the pyran rings are 90.9 (1) and 96.7 (1) degrees, respectively. In the crystal structure of (IIIa), intermolecular N-H.N and N-H...O hydrogen bonds link the molecules into infinite tapes along the b axis, while molecules of (IIIb) form centrosymmetric dimers via N-H...N hydrogen bonds, with only one H atom of the NH(2) donor group taking part in hydrogen bonding.