Tricyclo hepta-2,5-diene

Homoconjugation results in enhanced reactivity of substrates toward ionic hydrogenation. Bicyclo[2.2.1]hepta-2,5-diene forms a mixture of the trifluoroac-etate esters of bicyclo[2.2.1]hepten-2-ol, tricyclo[2.2.1.02 6]heptan-3-ol, and bicyclo[2.2.1]heptan-2-ol in a 62 20 17 ratio on treatment with 10 equivalents of triethylsilane and 20 equivalents of trifluoroacetic acid for 24 hours at room temperature (Eq. 96), 230... 

Scheme 6.33 Liberation of tricyclo[4.1.0.02,7]hepta-3,4-diene (142) from 7,7-dibromotetracyclo[4.1.0.02,4.03,5]heptane (141) and formation of [2 + 2]-cycloadducts of 142.

Actually, the earliest derivative of a vinylcyclopropane radical cation was a serendipitous discovery. It was formed by an unusual hydrogen shift upon photo-induced electron transfer oxidation of tricyclo[4.1.0.0 ]heptane (26). This result has been questioned on the grounds that the same rearrangement was not observed in a Freon matrix. However, there is no basis for the assumption that radical cation reactions in frozen matrices at cryogenic temperatures should follow the same course as those at room temperature in fluid solution and in the presence of a radical anion, which is potentially a strong base. In several cases, matrix reactions have taken a decidedly different course from those in solution. For example, radiolysis of 8 in a Freon matrix generated the bicyclo[3.2.0]hepta-2,6-diene radical cation (27 ), or caused retro-Diels-Alder cleavage yet, the... 

Anhydrous silver-olefin complexes are readily dissociable, low-melting, and variable in composition 92a, 176, 183). Cyclic olefins and polyolefins form stable complexes with silver nitrate or perchlorate, but again the Stoichiometry of the complexes varies considerably, sometimes depending on the conditions of preparation. The following types have been isolated [Ag(un)2]X (un = e.g., cyclohexene, a- and /3-pinene) ISO), [Ag(diene)]X diene = e.g., dicyclopentadiene 220), cyclo-octa-1,5-diene 50, 130), bi-cyclop, 2,1 ]hepta-2,5-diene 207), and cyclo-octa-1,3,5-triene 52), and [Ag2(diene)]X2 (diene = e.g., cyclo-octa-1,3- and -1,4-diene 180), bi-cyclo[2,2,l]hepta-2,5-diene 1) and tricyclo[4,2,2,0]-decatriene 10)). Cyclo-octatetraene (cot) forms three adducts with silver nitrate 52), viz., [Ag(cot)]NOs, [Ag(cot)2]N03, and [Ag3(cot)2](N03)3. On heating, the first two lose cyclo-octatetraene and all three decompose at the same temperature. From the stoichiometry of the above complexes it appears that the... 

Of the photochemical conversions of 3,6-bridged cyclohexa-1,4-dienes to 3,6-bridged syn-tricyclo[3.1.0.0 ]hexanes, the light-induced isomerization of norbornadienes to quadricyclanes (see Houben-Weyl, Vol.4/5a, pp 232-237) has been most intensively studied. The parent hydrocarbon, quadricyclane (1, tetracyclo[3.2.0.0 . 0 ]heptane) has become available on a preparative scale by acetophenone sensitized isomerization of norbornadiene (bicyclo [2.2.1]hepta-2,5-diene). ... 

Diazopropane (10 mmol) in 12 was added in small portions to a solution of bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarbonitrile (1.1 g, 8 mmol) in EtjO at between — 40"C and - 50°C. The temperature of the mixture was allowed to rise to 25 °C and the progress of the reaction was followed by chromatography. The 5,5-dimethyl-3,4-diaza-exo-tricyclo[5.2.1.0 ]deca-3,8-diene-2,6-dicarbonitrile (6b) produced was purified by chromatography [silica gel, 30% EtjO in petroleum ether (bp 40-60°C)] yield 441 mg (26%) ... 

Various bi- and oligocyclic ring systems, such as norcaradiene (1 bicyclo[4.1.0]hepta-2,4-diene), bicyclo[6.1.0]nona-2,4,6-triene (2), bullvalene (3 tricyclo[3.3.2.0 ]deca-3,6,9-triene), semibul-Ivalene (4 tricyclo[3.3.0" ]octa-2,7-diene), barbaralone (5 tricyclo[3.3.1.0 ]nona-3,6-dien-10-one) and many other systems containing divinylcyclopropane subunits, exhibit interesting transition metal mediated reaction pathways leading to new carbon skeletons. ... 

Bicyclo 2.2.1 hepta-2,5-dien-<7-spiro-3>-l,4-dioxan-<2-spiro-7>-tricyclo 2.2.1.0 .0 - heptane 2205... 

Dicyclopentadiene reacts with PH3 (mole ratio 3 1) in toluene at 90 C in the presence of AIBN to give a secondary phosphane (viscous yellow oil) of unknown constitution [79]. The addition of PH3 successively to bicyclo[2.2.1]hepta-2,5-diene and 1-octadecene in the presence of AIBN to give a mixture of bicyclic tertiary phosphane isomers is described in [183]. 1,5,9-Cyclododecatriene (90% trans,trans,trans isomer 10% trans,trans,cis isomer) reacts with PH3 on irradiation with °Co radiation at 100 to 140 C to give a mixture of cis and trans isomers of 1 -cyclododeca-4,8-dienylphosphane, 13-phospha-tricyclo[6.4.1.0 ]tridecane, and 13-phospha-tricyclo[7.3.1.0 ]tridecane. The conversion of the cyclodecatriene was 53% [80]. 

Bicyclo[3.2.0]hepta-2,6-diene Degenerate Rearrangement and Isomerization to 1,3,5-Cycloheptatriene Tricyclo[4.1.0.0 ]heptene 180... 

Finally, tricyclo[4.1.0.0 ]hept-3-ene gives almost exclusively bicyclo[3.2.0]-hepta-2,6-diene upon heating at 150°C with a half-life of 1.5 h (Scheme 8.17). " It was suggested that this rearrangement involves the symmetry-allowed opening of the bicyclobutane to a 1,3,5-cycloheptatriene with one trans double bond followed by conrotatory closure to the bicycloheptadiene. 

The addition of thermally generated difluorocarbene to bicyclo[2,2,l]hepta-2,5-dienes has been found to give the homo-Diels-Alder product (103 R = H) in addition to the endo- and exo-tricyclo-octanes (104 R = H) and (105 R = It is thought that the homo-addition product results from concerted cheletropic reaction and, by... 

Bis-(2,3,4-trimethyl-l-methylenecyclobut-2-en-4-yl) mixed at —5° with HBr in glacial acetic acid whereupon the temp, rises to 20°, and the product isolated after ca. 15 min. when the upper layer has become solid 1,2,3,4,7,8,9-hepta-methyl-syn-tricyclo[5.2.0.02-5]nona-3,8-dien-5-yl bromide. Y 88%. F. e. s. R. Criegee, J. Dekker, and H. A. Brune, B. 96, 2368 (1963). 

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