Crystal structures of methyl (E)-3-(2-chloro-phen-yl)-2-({2-[(E)-2-nitro-vin-yl]phen-oxy}meth-yl)acrylate and methyl (E)-2-({4-chloro-2-[(E)-2-nitro-vin-yl]phen-oxy}meth-yl)-3-(2-chloro-phen-yl)acrylate.

The title compounds, C19H16ClNO5, (I), and C19H15Cl2NO5, (II), both crystallize in the monoclinic space group P21/n. They differ essentially in the orientation of the methyl acetate group, with the C=O bond directed towards the NO2 group in (I) but away from it in (II). In compound (I), the mean plane of the methyl acrylate unit is planar, with a maximum deviation of 0.

Crystal structure of (5-chloro-2-hy-droxy-phen-yl)(3-methyl-isoxazolo[5,4-b]pyridin-5-yl)methanone.

In the title compound, C14H9ClN2O3, the fused pyridine and isoxazole rings are approximately planar, making a dihedral angle of 1.14 (16)°. The mol-ecule is twisted with the benzene ring and the mean plane through the fused pyridine-isoxazole ring system being inclined to one another by 47.

Crystal structure of 1-methyl-2-methyl-amino-3-nitro-1H-chromeno[2,3-b]pyridin-5(10aH)-one.

In the title compound, C14H13N3O4, the pyran ring adopts an envelope conformation with the methine C atom as the flap. The dihedral angle between the benzene and hydro-pyridine rings is 29.33 (3)°.

Crystal structure of 5-(5-chloro-2-hydroxy-benzo-yl)-2-(2-methyl-1H-indol-3-yl)nicotino-nitrile.

In the title compound, C22H14ClN3O2, the indole unit is essentially coplanar, with a maximum deviation of 0.035 Å for the C atom bearing the methyl group. The central pyridine ring is inclined to the indole ring system by 43.

Crystal structure of (2-hy-droxy-5-methyl-phen-yl)(3-methyl-1-phenyl-1H-pyrazolo-[3,4-b]pyridin-5-yl)methanone.

In the title compound, C21H17N3O2, the 2-hy-droxy-5-methyl-phenyl ring and the phenyl ring are inclined to the mean plane of the pyrazolo-pyridine moiety (r.m.s.