Crystal structure of (E)-4,4'-(but-2-ene-1,4-di-yl)bis-(2-meth-oxy-phenol).

The title compound, C18H20O4, was synthesized via the ruthenium-catalyzed alkene methathesis dimerization of eugenol. The whole mol-ecule is generated by inversion symmetry; the center of inversion being located at the mid-point of the trans C=C bond. The phenol ring is inclined to the mean plane of the central C-C=C-C unit (r.

Crystal structure of 4,6-di-amino-2-(methyl-sulfan-yl)pyridine-3-carbo-nitrile.

The title pyrimidine derivative, C7H8N4S, is essentially planar, with a maximum deviation of 0.029 (2) Å from the mean plane of the non-H atoms. In the crystal, mol-ecules are linked by an inter-molecular bifurcated N-H⋯N hydrogen bond between the cyano N atom and the two amino groups, an N-H⋯N hydrogen bond between the two amino groups and a weak C-H⋯π inter-action, forming a three-dimensional network.

Crystal structure of N-[4-amino-5-cyano-6-(methyl-sulfan-yl)pyridin-2-yl]acetamide hemihydrate.

The title compound, C9H10N4OS·0.5H2O, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit, together with a water mol-ecule of crystallization. The acetamide moiety, which has an extended conformation, is inclined to the pyridine ring by 7.

Crystal structure of N-[4-amino-5-cyano-6-(methyl-sulfan-yl)pyridin-2-yl]-2-chloro-acetamide.

In the title compound, C9H9ClN4OS, the dihedral angle between the acetamide moiety and the pyridine ring is 4.83 (12)°. The O=C-C-Cl torsion angle is 46.

9-Allyl-9H-fluoren-9-ol.

The asymmetric unit of the title compound, C16H14O, contains two independent mol-ecules differing in the orientations of the allyl groups; the corresponding O-C-C(H2)-C(H) torsion angles are -61.01 (13) and -177.43 (10)°.

Santal monohydrate, an isoflavone isolated from Wye-thia mollis.

THE TITLE COMPOUND [SYSTEMATIC NAME: 3-(3,4-di-hydroxy-phen-yl)-5-hy-droxy-7-meth-oxy-4H-chromen-4-one monohydrate], C16H12O6·H2O, is a monohydrate of a natural product santal isolated from Wye-thia mollis. In the santal mol-ecule, the dihedral angle between the benzo-quinone and di-hydroxy-phenyl fragments is 53.9 (1)° and an intra-molecular O-H⋯O hydrogen bond occurs.

Isotenulin.

Isotenulin, C17H22O5, is a sesquiterpene lactone isolated from sneezeweed Helenium amarum. It crystallizes with two independent mol-ecules in the asymmetric unit. In each mol-ecule, two five-membered rings (cyclo-pentenone and lactone) are trans-fused to the central seven-membered ring.

Tenulin 0.25-hydrate, a sesquiterpene lactone isolated from Helenium amarum.

The asymmetric unit of the title compound, C17H22O5·0.25H2O [systematic name: 2-hy-droxy-2,2a,6,9a-tetra-methyl-2a,4a,5,6,6a,9a,9b,9c-octa-hydro-2H-1,4-dioxadi-cyclo-pent[cd,f]azulene-3,9-dione 0.25-hydrate], a natural product isolated from Helenium amarum, contains two independent tenulin mol-ecules and half a water mol-ecule of crystallization situated on a twofold rotation axis.

The true identity of the triterpene component of Wyethia mollis, a lanosta-diene containing a tetrahydropyran E-ring.

The crystal structure of a triterpene component of Wyethia mollis has been obtained and compared with the previously reported structure of the compound. The compound in the crystal structure, lanosta-8,24-dien-3-one, 16,23-epoxy-(161beta, 23R), (1), is different from the previously reported compound, but has identical NMR and mass spectrometric data. The revised structure contains a tetrahydropyran E ring, a structural moiety rare in steroid triterpenes.