Tricyclo octa-3,6-diene

When a small ring was fused to the bridge of TBP precursor 44a, strained cycloalkene would be formed in the rDA reaction. Thus, the rDA temperamre was expected to be raised in this case. Such precursors were prepared from cycloheptatriene 49e [55] and cyclooctatriene 49f [56]. The DA reaction of these diene equivalents with disulfonylethy-lene 4b proceeded via norcaradiene and bicyclo[4.2.0]octa-diene forms to give the tricyclo adducts 51e and 51f, which were transformed to precursors 53e-H2 and 53f-H2 in the usual manner (T. Okujima et al., manuscript in preparation). The rDA temperatures of 53e-H2 and 53f-H2 were proved to be extremely raised. Cyclopropane-fused 53e-H2 and cyclo-butane-fused 53f-H2 did not undergo the thermal rDA reaction below 265 and 180 C, respectively, and were successfully metallated with Cu(OAc>2 to give 53e-Cu and 53f-Cu (T. Okujima et al., manuscript in preparation). 

As is the case for [2 + 2] cycloaddition reactions (15-61), certain forbidden electrocyclic reactions can be made to take place by the use of metallic catalysts." An example is the silver ion-catalyzed conversion of tricyclo[4.2.0.0. ]octa-3,7-diene to cyclooctatetraene " ... 

It has been reported that irradiation of bicyclo[5.1.0]octa-3,5-dien-2-one (63) in methanol leads to a mixture of racemic tricyclo[4,2.0.03,5]oct-7-en-2-one (65), 37, and cyclohepta-l,3,5-triene35). Control of the reaction was also tried in expectation... 

Chelate complexes of the type [PdX2(diene)] (X = Cl, Br) are readily formed by the dienes hexa-1,5-diene (124), bicyclo 2,2,lJhepta-2,5-diene (1, 7) tricyclo[4,2,2,0]-deca-triene and -diene derivatives (10), cyclo-octa-1,5-diene and dicyclopentadiene, but not dipentene (43). These may be converted to complexes of the types [Pd2X2(dieneOR)2] and [PdCl(dieneOR)-(amine)] (R = alkyl) (43), and their properties indicate that they have similar structures to the platinum complexes (XXXI) and (XXXIII). 

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... 

Similarly, cycloaddition of 4-toluenenitrile oxide to cyclobutadiene gave a 2 2 adduct,26 whose configuration was not determined, but it is believed that this adduct was formed from the cycloaddition of nitrile oxide to the C —C double bonds of the major dimer of cyclobutadiene, namely A > -tricyclo[4.2.0.02 5]octa-3,7-diene.26... 

Cyclobutadienes represent very reactive alkenes that undergo both [2 + 2] as well as [4 + 2] cycloadditions. Both the cyclodimerizations, mixed [2 + 2] cycloadditions and Diels-Alder reactions of these reactive species have been reviewed (see Houben-Weyl, Vols. 4/4, p 231 and E 17 f, Section 10B). In most instances the initially formed cyclodimer is tricyclo[4.2.0.02-5]octa-3,7-diene (36) and has the all cis-syn configuration. This is attributed to the concerted [4n -I- 2n] cycloaddition mechanism in which stereochemical control is affected by secondary orbital interactions. 

Direkte UV-Bestrahlung wandelt Cycloocta-l,3,5-trien (Formel 121) hauptsachlich in Bicyclo[4,2,0]octa-2,7-dien (Formel 122) und Tricyclo-[3,2,l,0a-8]oct-3-en (Formel 123) (58,222,340) um. Daneben werden noch all-trans-Octatetra-l,3,5,7-en (222) und Cyclo-octa-l,5-dien (58) nach-gewiesen. 

Erhitzen (oder UV-Bestrahlung) der 2,2,2-Triorgano-2A5-homocubane fiihrt unter Abspaltung des entspre-chenden Phosphans zu syn-Tricyclo[4,2.0.0.2 5]octa-3,7-dien, das sich zum Cyelooctatetraen umlagert2 ... 

Nickela-tricyclo[4.1.1.0l, octa-2,4-dien (1,2-Bis-[dimethylamino]-ethan)-8,8-difluor- E17d, 2951 (1,1-F2— lH- + Ni-Komplex)... 

Rhodium(I) complexes are efficient catalysts for the valence isomerizations of cubane (23a equation 7) and its derivatives to the corresponding iy/j-tricyclo[4.2.0.CF ]octa-3,7-dienes. When a stoichiometric amount of [ RhQ(CO)2)2l is added to a chloroform solution of cubane, the organorhodium compound (24) is obtained in about yield. Treatment of (24) with a stoichiometric amount of triphenylphos-phine gives, in about 90% yield, the polycyclic ketone (25) together with a small amount (5-10%) of cy-clooctatetraene. A similar reaction is also reported for the methoxycarbonyl derivative (23b). 

Full details of the effects of acid and solvent polarity on various photocycloaddition reactions of ethylenes and acetylenes to benzene have been published and a mechanistic rationale of the observations has been presented. Thus the largely homopolar concerted meta cycloaddition of ethylenes to benzene, which yields the tricyclo[3.3.0.0 "]oct-3-ene system (36), has little sensitivity to either solvent polarity change or the presence of a proton donor, but the onho process leading to bicyclo[4.2.0]octa-2,4-diene derivatives (37)... 

A very rapid degenerate Cope rearrangement was observed for tricyclo[3.3.0.0 ]octa-3,6-diene(semibullvalene), 301. The H-NMR spectrum showed type A protons at 5.08 ppm, type B at 4.17 ppm and type C at 2.97 ppm and was unchanged between — 110° C and -I-117° C three absorptions only were shown in the C-NMR spectrum. ... 

Interest in the chemistry of tropyl azide stems from the prediction that a multiplicity of products might arise by unimolecular decomposition or self-reactions. Wulfman and Ward have in fact presented spectroscopic evidence for the formation of the unique sandwich compound (163), resulting from the interaction of tropyl azide and the derived 1-aza-tricyclo [3,3,0,0 ] octa-3,6-diene (164). 

Bicyclo[2.2.2]octa-2,5-diene and tricyclo[3.2 2.0 " ]nona-6,9-diene derivatives react with palla-dium(II) acetate in the presence of sodium acetate in anhydrous benzene to give the formal homo-Diels-Alder cycloadducts 16 and 17 of dehydrobenzene. ... 

The photoreactions of acyclic and cyclic alkenes with benzene depend on the ionization potential of the alkene relative to that of benzene, In general meta cycloaddition to give tricyclo[3.3.0.0 ]oct-3-ene derivatives occurs to some degree in every case and often predominates. ortho Cycloaddition tends mostly to occur with alkenes of lower ionization potential than benzene and gives bicyclo[4.2.0]octa-2,4-diene derivatives para cycloaddition gives bi-cyclo[2.2.2]octa-2,5-diene derivatives to a smaller extent. 

When a mixture of benzene and perfluorobutyne was irradiated in a Vycor tube with 253.7 nm light, slow formation of at least eight compounds was detected by gas chromatography. The major compound was l,2-bis(trifluoromethyl)cycloocta-l,3,5,7-tetraene (10, 40%), accompanied by three isomeric bis(trifluoromethyl)tricyclo[3.3.0.0 ]octa-3,6-dienes (semibullvalenes) 11-13 in 25, 12 and 5% yield, respectively. ... 

Irradiation of a solution of dimethyl acetylenedicarboxylate in a 14-fold molar excess of molten naphthalene at 90 °C with UV light for four days in a quartz apparatus gave an 11 % yield of 1 1 adducts, among which the major product (34%) was dimethyl 3,4-benzo-tricyclo[3.3.0.0 ]octa-3,6-diene-6,7-dicarboxylate (14). ... 

One of the first examples of the di-7t-methane rearrangement was found in the photochemical conversion of bicyclo[2.2.2]octa-2,5,7-triene (barrelene, 1) to tricyclo[5.1.0.0 ]octa-2,5-diene (semibullvalene, 2). ... 

In contrast to norbornadiene, bicyclo[2.2.2]octa-2,5-diene does not always give the transan-nularly bridged products in normal solution reactions, whereas in the anodic electrooxidation this nonconjugated octadiene showed the formation of products, mainly tricyclo-[2.2.2.0 ]octane derivatives 5 and 6 from transannular interaction, exclusively. ... 

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