The synthesis of tricyclo[5.2.1.01 234'10]deca-2,5,8-triene (1), 1,10-dimethyltricyclo[5.2.1.04,1°]deca-2,5,8-triene (3), and tetracyclo[5.5.2.01,8.04,8]tetradeca-2,5,13-triene (4) has been accomplished via the reaction of 1,2-dicarbonyl compounds with di-zerz-butyl 3-oxoglutarate (Weiss reaction). Condensation of glyoxal 5a with di-rerZ-butyl 3-oxoglutarate (6b) gave the tetra-te/7-butyl w-dioxobicyclo[3.3.0]octane-2,4,6,8-tetracarboxylate 7b in 93% yield. This bisenol 7b was converted into the bisenol ether 9b regios pecifically (90% yield). This transformation was followed by monoalkylation (KH, allyl iodide; -58 °C) and hydrolysis to generate 2-allyl-n4-bicyclo[3.3.0]octane-3,7-dione in 90% overall yield from 9b. The mixture of epimeric 2-allyl-3,7-diones 11a,b was transformed (03; DMS) into the mixture of epimeric aldehydes 12a,b. This process was followed by aldol cyclization (2 N HC1, THF) to provide the diastereomeric mixture of endo-(13a) and exo-(13b) triquinane monols in 85% yield. Reduction of 13a,b with borane-THF (0 °C) generated the stereoisomeric mixture of triols 14a,b which were subjected to an HMPA-mediated dehydration sequence to provide triquinacene (1), accompanied by small amounts of isotriquinacene. The mixture of trienes were converted into pure 1 by exposure to p-TSA in methylene chloride-pentane. Substitution of biacetyl (5b) for glyoxal 5a in the Weiss reaction, followed by the analogous steps detailed in the synthesis of 1, provided 1,10-dimethyltriquinacene (3). In addition, the synthesis of 1,10-cyclohexanotriquinacene (4), another centro-substituted triquinacene, has been accomplished by substitution of cyclohexane-1,2-dione (23) for 5a in the condensation, followed by the same sequence of reactions presented above for 1 and 3.
1) (a) Katz, T.; Rosenberger, M.; OHara, R. K. J. Am. Chem. SOC. 1964,86,249-252. (b) Hafner, K.; Sibs, H. U. Angew. Chem., Znt. Ed. Engl. 1973,12,576-577. Hafner, K.; Dbnges, R.; Goedeck, E.; Kaiser, R. Angew. Chem. 1973,85,362-364. Dbnges, R.; Hafner, K.; Lindner, H.-J. Marty, R. A.; de Mayo, P. J. Am. Chem. SOC. 1971, 93, 3071-3072; Baird, N. C.; West, R. M. J. Am. Chem. SOC. 1971, 93, (2) Butenschh, H.; de Meijere, A. Tetrahedron 1986,42,1721-1729 and references cited therein. Lendvai, T.; Friedl, T.; Butenschbn, H.; Clark, T.; de Meijere, A. Angew. Chem., Znt. Ed. Engl. 1986,25,719-720. 3072-3073. 0022-3263/88/l953-2327$01.50/0 Scheme I W H Scheme I1 9 Z [7.2.1.04J1.08~10]dodeca-l,3,5,7,9(12)-pentaene (2) have been discussed only from a theoretical point of view despite the preparation of the carbon skeletons of these molecules by several group^.^-^ (3) Uggeri, F.; Srikrishna, A,; Eaton, P. E. J. Org. Chem. 1984, 49, 1728-1732. McKervey, M. A.; Vibuljan, P.; Ferguson, G.; Siew, P. J. Chem. Soc., Chem. Commun. 1981,912-914. 0 1988 American Chemical Society cis-bicyclo[3.3.0]octane derivatives from reaction of substituted glyoxals with dimethyl 3-oxoglutarate (Scheme I).This process has now been employed to provide simple entry into the requisite ring systems of the three annulenes, suitably functionalized (OH) for later conversion into 1-3. Controversy exists as to whether polyquinenes such as 1-3 are delocalized, exhibit aromatic Hiickel "type" stability, or exist as alternate hydrocarbons that behave as highly reactive olefinsP16 This controversy provided the impetus for the present study.Earlier, during the synthesis of triquinacene8 the tetraester 6b, which is readily available from glyoxal (4a) and di-tert-butyl3-oxoglutarate (5b), was converted into the bisenol ether. This tetraester could be monoalkylated in >go% yield and converted into triquinacene.8 This ~ (4) Fukunaga, T.; Clement, R. H. (6) Venkatachalam, M.; Deshpande, M. N.; Jawdosiuk, M.; Kubiak, G.; Wehrli, S.; Weiss, U.; Cook, J. M. Tetrahedron 1986,42,1597-1605.
The dimerization of triquinacene (CioHio) to dodecahedrane (CZ0HZO) has been a goal of organic chemists for more than three decades. An attempted synthesis of dodecahedrane from triquinacene using high pressure and near-UV radiation was not successful, but both hydrocarbons survived the 15 GPa treatment. There is no evidence for a pressure-induced transition in either of the materials. The results of high-pressure Raman spectroscopic investigations to 20 GPa on triquinacene and dodecahedrane are reported. Liquid triquinacene crystallizes near 0.2 GPa at 295 K and the Raman peaks associated with the molecular modes sharpen strikingly. In the crystal the extemal mode peaks exhibit a large pressure dependence, as expected, but the surprising fact is that the C-H stretching modes behave likewise. In dodecahedrane a similar effect is observed for the C-H stretching modes, but no extemal mode peaks are observed. The Raman data on dodecahedrane are compared with earlier results and calculations, which support the I , symmetry for the molecule and an fcc lattice for the crystal. Chem. 71,352 (1993).La dimkrisation du triquinacene (CIoHlo) en dodkcakdrane (C,,Hz0) a kt6 un des objectifs des chimistes organiciens depuis plus de trois dkcennies. Un essai de synthkse du dodkcakdrane a partir du triquinackne en faisant appel a une radiation du proche UV, a haute pression, n'a pas Ctk couronnk de succks; toutefois, les deux hydrocarbures ont survkcu au traitement a 20 GPa. On n'a pas de donnkes suggkrant une transition induite par la pression de ces composks. On rapporte les rksultats d'etudes par spectroscopie Raman a haute pression, allant jusqu'a 15 GPa, du triquinackne et du dodkcaedrane. Le triquinackne liquide cristallise a 295 K, a 0,2 GPa, et les bandes Raman associkes avec les modes molkculaires sont fortement affinkes. Dans le cristal, comme on pouvait s'y attendre, les bandes du mode externe varient beaucoup en fonction de la pression; toutefois, il est surprenant de rkaliser que les modes d'elongation C-H se comportent de la m&me manikre. Dans le dodkcakdrane, on observe un effet similaire pour les modes de vibration C-H; toutefois, on n'observe aucune bande du mode externe. On compare les donnkes Raman relatives au dodkcakdrane avec les rksultats obtenus antkrieurement ainsi qu'avec des calculs qui supportent la symktrie I, pour la molCcule et un rkseau fcc pour le cristal.[Traduit par la rkdaction]
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