The title compound, C(15)H(18)O(3), was synthesized from 9α-hy-droxy-parthenolide (9α-hy-droxy-4,8-dimethyl-12-methyl-ene-3,14-dioxatricyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one), which was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The five-membered lactone ring has a twisted conformation, while the six- and five-membered rings display chair and envelope conf...

In the title salt, C14H17N2(+)·Cl(-), the central N atom is pyramidal (sum of bond angles = 330.9°) and there is a near orthogonal relationship between the benzene rings [dihedral angle = 89.95 (10)°]. The crystal packing features N-H⋯Cl hydrogen bonds, which lead to a supra-molecular undulating ribbon along the a axis comprising edge-shared eight-membered {⋯HNH⋯Cl}2 synthons. The chains are co...

The title compound, C(2)H(8)N(+)·C(10)H(11)N(2)O(5) (-), is a highly toxic herbicide known as dinoseb. The sec-butyl group is disordered [occupancy ratio 0.828 (3):0.172 (3)], while the nitro group in the 6 position is twisted by 25° with respect to the ring plane. Pairs of -O(-)⋯H-N(+)-H⋯(-)O- bridges between phenolic O atoms generate eight-membered hydrogen-bonded rings.

A versatile and metal-free approach for the synthesis of carbocycles and of heterocycles bearing seven- and eight-membered rings is described. The strategy is based on ring expansion of 1-vinylcycloalkanols (or the corresponding silyl or methyl ether) mediated by the hypervalent iodine reagent HTIB (PhI(OH)OTs). Reaction conditions can be easily adjusted to give ring expansion products bearing ...

The title compound, C(18)H(13)Cl(11), is an undecachlorinated commercial flame retardant. The asymmetric unit contains two independent half-mol-ecules. The complete mol-ecules are generated by crystallographic inversion symmetry, causing the terminal H atoms and one of the Cl atoms to be disordered equally over two sites in each mol-ecule. The central eight-membered rings are in chair-type conf...

The facile preparation of a racemic hydrazine bridged diphosphonium compound possessing a ring system analogous to bicyclo[3.3.2]decane is reported. Although the reaction yield is low, the structure of the compound, which possesses an eight-membered ring, two phosphonium cationic centers, a biimino bridge, molecular chirality and two fused aromatic rings locked into roughly perpendicular planes...

The central eight-membered ring of the title compound, C40H36N8O2, deviates from the ideal boat conformation because the bond between the exo-ethyl-ene group and the adjacent N atom is twisted by 60.0 (4)° due to steric hindrance. Its adjacent benzene and pyrazole rings are oriented almost perpendicular to each other, making a dihedral angle of 85.8 (3)°. In the crystal, the mol-ecules are link...

Lancolide E (1) featuring a complex tetracyclo[5.4.0.0(2,4).0(3,7)]undecane-bridged system that is constructed by an eight-, a three-, and two five-membered carbon rings in a sterically congested region was obtained in trace amounts from a "talented" schinortriterpenoid producer Schisandra lancifolia. Its structure was fully characterized by combining 2D NMR spectroscopy, theoretical calculatio...

The main mol-ecule of the title compound, C(66)H(38)O(2)·CH(2)Cl(2), is centrosymmetric, the asymmetric unit is composed of two half-mol-ecules, located on inversion centers, and a mol-ecule of dichloro-methane. The large π-conjugated fused polycyclic system including eight six-membered rings is nearly planar, with r.m.s. deviations of 0.2114 and 0.2081 Å in the two independent mol-ecules.

The title compound, C(19)H(19)N(3)O(4)S(2), was prepared by the reaction of 2,3-diamino-pyridine with tosyl chloride in a mixture of dichloro-methane-pyridine as solvent. In the crystal, mol-ecules associate via pairs of N-H⋯N hydrogen bonds, forming a centrosymmetric eight-membered {⋯HNCN}(2) synthon. The dihedral angles between the amino-pyridine ring and the tosyl benzene rings are 50.01 (6)...