B. A. Lloyd

Ketone pyramidalization in a tetracyclic perpendicular enone derivative

Endo,exo- 11,11-Dimethoxytetracyclo[6.2.1.13 3,6 .0 2,7 ]dodeca-9-en-12-one (1), C 14 H 18 O 3 , M r =234.30, monoclinic, P2 1 /n, a=14. 1 13 (2), b=10.032 (1), c=17.086 (2) A, β=103.55 (1) o , V=2351.74 A 3 , Z=8, D x =1.323 g cm -3 , λ(Cu Kα)= 1.54056 A, μ=7.038 cm -1 , F(000)=1008, T= 133 K, R=0.0433 and wR=0.0435 for 4255 unique reflections. The molecule contains a norbornanone unit fused to a substituted norbornene. The ring C atom of the ketone is sigificantly pyramidalized

endo,endo-Tetra­cyclo­[6.2.1.13,6.02,7]dodeca-9-en-anti-11-yl 4-bromo­benzoate

The title compound 1-OPBB, C19H19BrO2, contains a dechlorinated and hydrogenated isodrin backbone with an anti-4-bromobenzoate substituent at one of the methano bridges. The dihedral angle between the CO2 ester plane and the benzene ring plane is 8.5 (2)°. In the crystal, the ester groups stack over benzene rings: the molecules pack as conformational enantiomers, with nearest parallel benzene ring planes separated by a perpendicular distance of 3.339 (1) Å. The nearest benzene-ring centroids are 5.266 (1) Å apart. Possible structural correlation with enhanced solvolytic reactivity is investigated.

Bicyclo­[2.2.1]hept-7-yl p-bromo­benzoate

The title compound, C14H15BrO2, contains a sterically unencumbered norbornyl group. The dihedral angle between the plane of the carboxylate group and the mean plane of the adjacent benzene ring is 5.3 (2)°. The dihedral angle between the plane of the carboxylate group and the norbornyl methano C—O bond is 4.5 (1)°, the methano C atom deviating by 0.141 (2) Å from this plane. In the crystal, molecules pack as pairs of enantiomers, with a distance of 3.747 (1) Å between the centroids of nearest parallel benzene rings.

Bicyclo-[2.2.1]hept-2-en-7-yl 4-bromo-benzoate.

The structure of the title compound, C14H13BrO2, which contains a norbornenyl group and a 4-bromobenzoate ester at the single C-atom bridge, has been redetermined [see McDonald & Trotter (1965 ▶). Acta Cryst. 19, 456–463] to modern standards to establish high-precision geometrical data to compare with norbornyl and other tetracyclic 4-bromobenzoates. Possible structural evidence is sought to help explain solvolytic reactivities.

A norbornenyl derivative with through-space ketone π-interaction

The title compound, endo,exo-12-oxotetracyclo[6.2.1.1(3,6).0(2, 7)]dodeca-9-en-anti-11-yl p-bromobenzoate, C(19)H(17)BrO(3), consists of norbornene with an anti-p-bromobenzoate substituent at the methano bridge and an exo-fused norbornanone unit bonded to the ethano bridge. The spatially proximate ketone and alkene interact through space and the ketone C atom is substantially pyramidalized. Through-space ketone pi-interaction is probably responsible for the low solvolysis rate of the anti-11-chloride derivative.

A structure with through-space cyclopropyl π-interaction

The crystal structure determination of endo,endo-pentacyclo[7.2.1.1 3,7 .0 2,8 .0 4,6 ]tridec-10-en-anti-12-yl p-bromobenzoate, C 20 H 19 BrO 2 (1-OPBB), is reported. The molecule consists of norbornene with an anti-p-bromobenzoate substituent at the methano bridge, and with an endo-norbornyl unit endo-fused to the ethano bridge. The norbornyl unit also has an exo-cyclopropyl ring on the two-C-atom bridge opposite the ring fusion. Interbridge steric interactions are discussed, and some comparisons are made with other norbornenyl derivatives.

Structural investigations of a tetracyclic endo-norborenyl derivative

The X-ray crystal structure of endo,exo-tetracyclo-[6.2.1.1 3,6 .0 2,7 ]dodec-9-en-anti-11-yl p-bromobenzoate, C 19 H 19 BrO 2 (1), was determined at 148 K. The molecule consists of norbornene with an anti-p-bromobenzoate substituent at the methano bridge and an exo-norbornyl unit endo-fused to the ethano bridge. Structural comparisons are made with another derivative and steric interactions examined

Structural comparisons of a perpendicular diene with known derivatives

The X-ray crystal structure determination of endo,exo-12-methylenetetracyclo[6.2.1.1 3,6 .0 2,7 ]dodec9-en-anti-11-yl p-bromobenzoate, C 20 H 19 BrO 2 (1), is reported. The molecule consists of norbornene with an anti-p-bromobenzoate substituent at the methano bridge and an exo-methylenenorbornyl unit endo-fused to the ethano bridge. The ring C atom of the exocyclic double bond is pyramidalized significantly. Steric interactions are examined and some structural comparisons are made with other derivatives

A twisted pentacyclic ketone derivative

exo-11-Methoxy-9-methylpentacyclo[6.3.1.0 3,10 . 4,12 .O 5,9 ]dodecan-2-one (1), C 14 H 18 O 2 , M r =218.30, orthorhombic, Pbca, a=7.288 (1), b=12.432 (3), c=24.392 (2) A, V=2209.88 A 3 , Z=8, D x =1.311 g cm -3 , λ(Cu Kα)=1.54056 A, μ=6.425 cm -1 , F(000)=944, T=148 K, R=0.0547 and wR=0.0552 for 1602 unique reflections. The molecule consists of a «twisted» pentacyclic hydrocarbon ring system with methyl and methoxy substituents and a ketone functional group