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C 10 H 16 O 4 cristallise dans P2 1 /n avec a=8.264, b=6.988, c=18.288A, β=96.27°, Z=4; affinement jusqu'a R=0.043. C 16 H 18 O 5 cristallise dans P2 1 /n avec a=12.792, b=8.937, c=13.089A, β=91.37°, Z=4; affinement jusqu'a R=0.048. C 16 H 18 O 5 cristallise dans Pbca avec a=10.773, b=25.953, c=10.818A, Z=8; affinement jusqu'a R=0.048. L'heterocycle dioxolane adopte une conformation entre la demi-chaise et l'enveloppe pour les deux premiers composes, une conformation enveloppe pour le dernier.

C 16 H 16 O 4 cristallise dans P2 1 2 1 2 1 avec a=7,330, b=8,992 et c=21,416 A, Z=4; affinement jusqu'a R=0,032. C 16 H 16 O 4 cristallise dans C2/c avec a=26,131, b=7,634 et c=14,158 A, β=104,78 o , Z=8; affinement jusqu'a R=0,047. Les deux molecules assurent une conformation a l'etat solide qui ressemble a celle de l'isocolchicine plutot qu'a celle de la cochicine. L'angle diedre entre les cycles est 52,6 et 43,4 o respectivement (53 o dans la colchicine)

X-ray analyses have established the structures of (3aα,7aα)-6-chloromethyl-8,8-dichloro-2,3-dihydro-5-methoxy-3a,7a-methano-1H-indene, C 12 H 13 Cl 3 O, and (3aα,8aα)6,9,9-trichloro-2,3 5,8-tetrahydro-1H,4H-3a,8a-methanoazulen-5-one, C 11 H 11 Cl 3 O, which have resulted from different modes of cyclopropane ring cleavage within the framework of two closely related gem-di-chloro[4.3.1]propellanes.

The title compounds, (3aα,5α,6α)-4,4,6-trichloro-7-methoxy-3,4,5,6-tetrahydro-2H-3a,5-methanoazulene and (3aα,6α)-(E)-8,8-dichloro-5-chloromethylene-6-methoxy-1,2,3,4,5,6-hexahydrο-3a,6-methanο-3aH-indene, both C12H13C130, were formed by mild thermolyses of two related [4.3.1]propellanes and are of interest in the development of new methods for preparing novel analogues of the anti-cancer drug Taxol.

The title compound, (3aα, 10aα)-11,11-dibromo-6-methoxy-2,3,3a, 10a-tetrahydro-1H,4H-3a, 10a-methano-benz[f]azulen-9(10H)-one, C 16 H 16 Br 2 O 2 , is shown to contain a C6-methoxylated aromatic ring and bears some resemblance to the ABC ring system of paclitaxel (Taxol TM ).

The X-ray crystal structure of the title compound, C 10 H 11 Br 2 N, reveals that the three- and five-membered rings are fused to one another in a spiro fashion and that there is an E arrangement of substituents about the carbon-carbon double bond.

The X-ray crystal structure of C 19 H 20 BrNO 6 .0.5C 3 H 8 O, an ABC-ring analogue of the diterpene paclitaxel, establishes that the stereochemistry at C(10) is opposite to that seen in the natural product.

The X-ray crystal structure of the title compound, C 12 H 11 Br 4 NO 2 , reveals that the two three-membered rings are in an anti relationship to one another.

The X-ray structure analysis of the title compound, C12H11Br5O2, established the presence of the 2,3,3a,4,5,6-hexahydro-3a,6-methanoazulene ring system, which was produced by a reaction sequence involving unexpected skeletal rearrangement processes.

The X-ray crystal structure determination of the title compound (C20H22BrNO5, systematic name methyl 14-bromo-6-methoxy-1,3-dioxo-2,3,3a,9,10,11,12,13,13a,13b-decahydro-1H-8,12-methanocyclodeca[e]isoindol-12-yl acetate), an ABC-ring analogue of the diterpene paclitaxel reveals that the stereochemical relationships between C(3), C(4) and C(5) (C13a, C13b and C3a, respectively, by systematic numbering) are the same as observed in the natural product.

C 9 H 16 N 2 O 2 , M r =184.2, rhombohe dral, R3, a=12.594 (2) A, α=118.03 (1) o , V=720 (2) A 3 , Z=3, D x =1.274 Mg m -3 , A(Cu Kα)= 1.5418 A, μ=0.70 mm -1 , F(000)=300, T=290 (1) K, final R=0.047 for 1191 reflections with I ≥2σ(I). Although the title molecule (I) is a meso compound, it does not have exact mirror symmetry in the solid state. The observed distortions, which no doubt arise from the fusion of the two rings, results in two enantiomeric forms with any given crystal containing only the one enantiomer (e.g. with 3aS, 4R,7S,7aR configurations)

The title compound, C 12 H 12 O 2 , represents the first example of a molecule containing the perhydro-1,4-dioxacyclopropa[cd]pentalene ring system which has been subjected to single-crystal X-ray analysis.

The X-ray analysis of the title compound, C 14 H 12 BrNO, established the Z geometry about the propenyl double bond and also confirmed that the propenyl side chain is attached to the heterocyclic ring at the N atom rather than through the O atom.