A. Benharref

(1S,3R,8S,9S,10R)-2,2-Dichloro-9,10-epoxy-3,7,7,10-tetramethyltricyclo[6.4.0.01,3]dodecane and (1S,3R,8S,10R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo[6.4.0.01,3]dodecan-9-one

The stereochemistries of the title compounds, both C(16)H(24)Cl(2)O, have been established by X-ray diffraction. In both structures, the seven-membered ring adopts the same conformation, whereas the six-membered ring shows an envelope conformation in the epoxydodecane structure and a boat conformation in the dodecan-9-one structure.

Computational study of chemo- and stereoselectivity of α-cis, α-trans and α′-trans-himachalene epoxidation by MCPBA

Abstract Chemo- and steroselectivity studies of α- cis -himachalene, α- trans -himachalene and α′- trans -himachalene MCPBA epoxidation have been computed at the AM1 level of theory. The chemoselectivity is controlled by frontier molecular orbitals while the stereoselectivity is kinetically controlled. In agreement with experimental investigations, the monoepoxidation process occurs on the most substituted double bond. It is stereoselective for α- cis -himachalene and α- trans -himachalene but not for α′- trans -himachalene. Diepoxidation happens independently of monoepoxidation and is not stereoselective. We also notice that monoepoxidation is less asynchronous than diepoxidation.

2α,3α:6α,7α-Diépoxyhimachalane

The stereochemistry of the minor isomer, 3,4: 9,9a-diepoxy-3,5,5,9-tetramethyldecahydro- 1H-benzocyclo-heptene, C15H2402, resulting from the epoxidation of β-himachalene has been established. The atoms C10 and the gem-dimethyl groups C14 and C15 adopt two positions leading to two conformations for the seven-membered ring, boat-shaped (occupation factor 70%) and chair-shaped (30%). Modelling of these conformations agrees with the statistical distribution in the crystal.

2α,3α:7α,8α-Diépoxy-cis-himachalane

The stereochemistry of the major isomer resulting from the epoxidation of γ-cis-himachalene has been established as 2α,3α:7α,8α-diepoxy-γ-cis-himachalene, C 15 H 24 O 2 . Hence, the configurations of the two resulting derivatives have been deduced. The seven-membered ring is twist-chair shaped while the six-membered ring adopts a 1,2-diplanar conformation.

Cyclopropanation of a β-himachalene monoepoxide derivative

The stereochemistry of the title compound, (1S,2R,7S-8S, 10R)-9,9-dichloro-1,2-epoxy-2,6,6,10-tetramethyltricyclo[5.5.0.0. 8,10 ]dodecane, C 16 H 24 Cl 2 O, a derivative of β-himachalene, has been established. The epoxide bridge located at positions 1 and 2 on the seven-membered ring adopts a cis conformation with respect to the cyclopropane bridge located at positions 8 and 10 on the six-membered ring.

2α,3α:7β,13β-Diépoxy-trans-himachalane

The stereochemistry of the major isomer resulting from the epoxidation of α-trans-himachalene has been established. Hence, the configurations of the three resulting derivatives have been deduced. The seven-membered ring in the title compound, C 15 H 24 O 2 , is twist-chair shaped while the six-membered ring adopts a 1,2-diplanar conformation.

Reactivity of 6α,7α-epoxyhimachal-2-ene and crystal structures of 2α,3α-dibromocyclopropanehimachal-5,7-diene and 2α,3α-dibromocyclopropane-6α,7α-epoxyhimachalane

We report here the reactivity of 6α,7α-epoxyhimachal-2-ene with dibromocarbene generated in situ by phase-transfer catalysis. The stereochemistry of products resulting from dibromocyclopropanation has been established by X-ray crystallography. Compound 3 is orthorhombic P212121 with a = 7.549 (1), b = 8.432 (1), c = 24.469 (1) Å, V = 1559.8 (5) Å3, Z = 4 and compound 5 is monoclinic P21 with a = 8.779 (1), b = 15.684 (1), c = 12.111 (1) Å, β = 91.869 (1)°, V = 1666.7 (4) Å3 and Z = 4.

Some 1,3‐Dipolar Adducts from Benzodiazepine. II. Condensation of Nitrilimines with [1,4]Benzodiazepine and [1,4]Benzodiazepin‐2‐one

The structure of the diadduct ethyl 10-chloro-1-(4-chlorophenyl)-7-methyl-6-methylthio-11b-phenyl- 7,11b-dihydro-1H-[1,2,4]triazolo[4,3-d][1,4]benzodiazepine-3-carboxylate, C27H24Cl2N4O2S, has been established by X-ray crystallographic study. The central seven-membered ring is fused with chlorobenzo and triazolo rings to form the core of the molecule.

(1S,6S)-Tetrazolo[1,5-g]-7-aza-trans-himachal-2-ene

In the title compound, C 14 H 22 N 4 , the tetrazole ring is fused with the eight-membered ring of the himachal-2-ene skeleton, which is in a trans conformation.

1-(4-Chlorophenyl)-3a-methyl-5-phenyl-3a,4-dihydro-1,2,4-oxadiazolo[4,5-a][1,5]benzodiazepine

We report here the peri- and regioselectivity experienced in the 1,3-dipolar cycloaddition of 1,5-benzodiazepine to a nitrile oxide. The crystal structure of the title cycloadduct, C 23 H 18 ClN 3 O, shows that the condensation occurs at the N=C double bond at the 1 and 2 positions of the benzodiazepine.