Pentacyclo undecane

Polynitro derivatives of pentacyclo[5.4.0.0 .0 °.0 ]undecane have attracted interest as potential high-energy explosives. Molecular strain in this caged system could arise from both the constrained norbomyl moiety and the cyclobutane ring. Additional strain would be expected from nonbonding interactions if the S-endo and 1 l-endo positions were substituted with gm-dinitro groups. 

Marchand and co-workers have provided synthetic routes to both 8,8,11,11 -tetranitro- (72) and4,4,8,8,11,11-hexanitro- (80) pentacyclo[5.4.0.0 .0 °.0 ]undecanes. Initial attempts to synthesize target (72) from the dioxime (63) failed when it was found that sodium boro-hydride reduction of the gm-bromonitro intermediate (64) gave the aza-heterocycle (65) as the major product. Consequently, an indirect route was explored where one of the two ketone groups of (62) is protected as an acetal (66) while the other ketone group is converted to a... 

The reaction of 4-(dibromomethylene)pentacyclo[6.3.0.0 .0 °.0 ]undecane (11) with n-BuLi resulted in the corresponding vinylidenecarbene, 12a, which could be trapped in situ by cyclohexene to obtain the corresponding cage-functionalized exo-methylenecyclopropane (i.e., 13, Scheme 4). Compound 13 subsequently was characterized via conversion into 14 (Scheme 4), which structure was established unequivocally via single-crystal X-ray structural analysis [18]. 

Highly purified samples of heptacyclo[6.6.0.0 .0 .0 b0 .0 ° ]tetrad ecane (HCTD) and pentacyclo[5.4.0.0 .0 °.0 ]undecane (PCU) were sent to Prof. Kabo for study of their thermodynamic properties. The results of this study have been published in two papers which appeared in [38] and [39]. 

Intramolecular [2 + 2] photocycloadditions have been used successfully for the syntheses of (polycyclic) cage compounds. Recent examples of such reactions are the formation of pentacyclo[5.4.0.02 6.031°.05 9]undecane-8,ll-dione-4-spiro-l-cyclopentane,55 hexacy-clo[7.4.2.01,9.03,7.04 14.061s]pentadeca-10,12-diene-2,8-dione-5-spiro-l -cyclopropane,56 pen-tacyclo[5.4.0.02 6.031°.04 8]undecane57 and pentacyclo[6.4.0.02 7.03 12.06 9Jdodeca-4,10-diene.58 Irradiation of benzoquinone tetrahydropentalene adducts afford cage compounds which are easily converted to angular tetraquinanes.59... 

However, this cyclopropane to propene isomerization is the only reported preparative method for the synthesis of tetracyclo[3.3.3.0. 0 ]undec-9-ene 4) from pentacyclo-[3.3.3.0 -. 0 - .0. "]undecane (13). ... 

Pentacyclo[5.4.0.02 6.0310.05 9]undecane-8,ll-dione is reduced cither by baker s yeast or by horse liver alcohol dehydrogenase, but the enantiosclcctivity is only moderate (50-72%... 

Examples of compounds of globular molecules that form plastic crystals are methane, 2,2-dimethylpropane, tetrafluoromethane, tetrachloromethane, tetrabromomethane, cyclohexane, azacyclohexane, chlorocyclohexane, and hexachlorocyclohexane. Examples of hydrocarbons having caged stractures that have been recently fotmd to form plastic crystals are heptacyclo-[6.6.0 .0 0 ".0 .0 ° " ]tetradecane, [94-kab/koz] and pentacyclo[5.4.0 .0 °.0 ]undecane, [95-kab/koz]. The second compoimd is unusual in that the plastic crystal transition temperature is 164.4 K and the melting temperature is 475.8 K. This is a difference of 311.4 K. 

---