In the crystal structure of the title compound, C(43)H(46)NO(13)·0.5H(2)O, the mol-ecule assumes a U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The mol-ecule contains eight alicyclic and heterocyclic rings. The cyclo-hexane rings adopt chair conformations, the other three six-membered carbocyclic rings form a bicyclo-[2...

The reaction of 3-allyl-1,5-dimethyl-1,5-benzodiazepine-2,4-dione and benzaldoxime leads to the title compound, C(21)H(21)N(3)O(3). The mol-ecular structure is built up from two fused six- and seven-membered rings linked to a chain including a five- and six-membered ring (isoxazoline and phen-yl) via a methyl-ene group. The seven-membered ring displays a boat conformation. The dihedral angle be...

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. The five-membered rings each adopt envelope conformations. The seven-membered ring adopts a twist-chair confo...

The title compound, C(17)H(24)Cl(4), was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule is built up from fused six- and seven-membered rings and two three-membered rings from the reaction of β-himachalene with dichloro-carbene. The six-membered rin...

1,3-Diethyl-2-thio-barbituric acid reacts with 2,5-dimethoxy-benzaldehyde to form the title Knoevenagel product, C(19)H(22)N(2)O(4)S. In the compound, the two six-membered rings at either end of the three-membered -CHCHCH- chain are nearly coplanar with this fragment (r.m.s. deviation of the two six-membered rings and the three chain atoms = 0.08 Å).

Using simplified model derivatives, the assembly of the macrocyclic rings of madangamines, including the 13- and 14-membered D rings of madangamines C-E, the all-cis-triunsaturated 15-membered D ring of madangamine A, and the (Z,Z)-unsaturated 11-membered E ring common to madangamines A-E, has been studied.

Oxazinane rings can undergo isomerization or transformation to 5-membered tuned by the anomeric effect.

The title compound (delgradine), C(41)H(43)NO(12), is a hetisine-type C(20)-diterpenoid alkaloid, isolated from the roots of Aconitum carmichaeli Debx. In the crystal structure, the mol-ecule assumes an U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The mol-ecule contains eight alicyclic and heterocyclic rings. Cyclo-hexa...

The asymmetric unit of the title compound, C(15)H(15)ClN(4)O(6)S, contains two independent mol-ecules, in which the pyrimidine and benzene rings are oriented at dihedral angles of 75.21 (3) and 86.00 (3)°. Intra-molecular N-H⋯N and C-H⋯O hydrogen bonds result in the formation of two five- and two six-membered rings. The six-membered rings have flattened-boat conformations, while the five-member...