title: 2-Amino-4-(2-methoxyphenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile and 2-amino-4-(2-methoxyphenyl)-7,7-dimethyl-3-nitro-4,6,7,8-tetrahydro-5H-chromen-5-one hemihydrate.
abstract: Calculations of the conformational preferences of the methoxyphenyl substituent with respect to the pyran ring have been carried out for the two title compounds, C19H20N2O3, (II), and C18H20N2O5.0.5H2O, (III). In both molecules, the heterocyclic ring adopts a flattened boat conformation and the fused cyclohexenone ring adopts a 'sofa' conformation. The dihedral angles between these two flat fragments are 14.5 (1) and 9.3 (1) degrees in (II) and (III), respectively. In both molecules, the methoxy group of the pseudo-axial aryl substituent is syn with respect to the pyran ring. The dihedral angles between the 2-methoxyphenyl rings and the flat parts of the pyran rings are 86.3 (1) and 87.0 (1) degrees, respectively. In the crystal structure of (II), intermolecular N-H...N and N-H...O hydrogen bonds link molecules into a three-dimensional framework. In the crystal structure of (III), a strong intramolecular N-H...O hydrogen bond links the flat conjugated H-N-C=C-N-O fragment into a six-membered ring. In (III), the water molecule lies on a twofold axis and forms bifurcated O-H...O hydrogen bonds with the NO2 group of the molecule. Also in (III), hydrogen bonds link the organic and water molecules into infinite tapes along the c axis.
authors.affiliation: Department of Natural Sciences, New Mexico Highlands University, Las Vegas, NM 87701, USA. vnesterov@nmhu.edu
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Nesterov
authors.forename: Victor P
authors.initials: VP
authors.lastname: Kislyi
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Sabutis
authors.forename: Volodymyr V
authors.initials: VV
authors.lastname: Nesterov
authors.forename: David J
authors.initials: DJ
authors.lastname: Wiedenfeld
authors.forename: Victor V
authors.initials: VV
authors.lastname: Semenov
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009570:Nitriles / Q000737:chemistry*
chemical_list: D001578:Benzopyrans; D009570:Nitriles