Nesterov Vladimir N, Wiedenfeld David J, Nesterova Svitlana V, Hastings Lucas F
Department of Natural Sciences, New Mexico Highlands University, Las Vegas, NM 87701, USA.
Acta Crystallogr C. 2006 Dec;62(Pt 12):o705-8. doi: 10.1107/S010827010604844X. Epub 2006 Nov 30.
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) degrees 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.
已分别对两种标题化合物,即C15H14N2O2(II)和C20H16N2O2·C2H3N(III)进行了羰基取代基相对于吡喃环的构象偏好的合成、X射线结构研究及计算。在这两种分子中,杂环均呈扁平船式构象。在(II)中,羰基与杂环的一个双键是顺式的,但在(III)中它们是反式的。在(II)中,羰基与一个甲基氢原子形成短接触。在(II)和(III)中,假轴向苯基取代基与吡喃环平面部分之间的二面角分别为92.7(1)度和93.2(1)度。在(II)的晶体结构中,分子间的N-H...N和N-H...O氢键将分子沿(103)平面连接成层,而在(III)中,它们将分子沿a轴连接成带。