Bicyclo octadiene derivatives

Chemical Class Dibenzo-bicyclo-octadiene derivative... 

Deprotonation of an ester led to a Claisen condensation, giving a bis-anisylketo ester intermediate [24]. Acidification and thermal decarboxylation led to the desired bis-anisylketone [Eq. (17)]. This product was an intermediate to a bicyclo[3.2.1]octadiene derivative used in a study of anionic homoaromaticity. 

Bicyclo[3.3.0]octadiene derivatives of type 9 were prepared in excellent yields by the trimeth-ylaluminum or diethylaluminum chloride catalyzed rearrangements of cis- and ira/ii-isomers of vinylcyclopropane 7. The two isomers equilibrate under the reaction conditions. 

The 1,2-addition products may undergo rearrangement to bicyclo[4.2.0] octadiene derivatives or to open-chain compounds analogous to (IX)-... 

A useful compilation of 220 MHz n.m.r. data of substituted bicyclo[3,2,l]octan-6-ones has been published. The bicyclo[3,3,0]octyl cation appears to be implicated in the isomerization of bicyclo[3,2,l]oct-2-ene over SiOj-PaOj at 250 °C as deduced from the scrambling of label in [3- C]-tagged material and the distribution of label in the product, namely bicyclo[3,3,0]oct-2-ene. It has been found that 2,4-diphenyl-bicyclo[3,2,l]octa-2,6-diene (630) and its 6,7-dihydro-derivative undergo base-catalysed hydrogen-deuterium exchange at C-4 at essentially the same rate. Hence, the phenyl groups result in the total elimination of charge delocalization from C-4 to the C-6-C-7 double bond that is found in the unsubstituted bicyclo-octadiene. The... 

The CuBr2/amine-promoted 2 + 2-cycloaddition reaction of 1,4-bisallenes (17) produced bicyclo[4.2.0]octadiene derivatives (18) in a one-pot procedure (Scheme 7) Phosphoramidite ligands (19) activate the Au(I)-catalysed 2 + 2-cycloaddition reaction of A-allenylsulfonamides with styrenes, at -70 C, to form vinyl cyclobutane derivatives in high yields and enantioselectivity. A new Pt(II) catalyst with a hollow-shaped tri- ethynylphosphine activates the intermolecular 2 + 2-cycloaddition reaction of allenyl silyl ether with vinyl ethers to yield methylenecyclobutanes in good yield. 

New P-substituted benzo- and naphthofuryl derivatives of o-divinylbenzene were synthesized and irradiated in order to form annulated bicyclo[3.2.1]octadienes. The mechanism of the intramolecular (2+2]-cycloaddition was explained <99H(51)1355>. 

The following hydrocarbons have been successfully substituted for 1,5-cyclo-octadiene in this procedure to yield the corresponding dibromo (olefin )platinum (II) derivatives 1,3,4,7-cyclooctatetraene, dicyelopentadieno (3a,4,7,7[Pg.50]

Dowbenko (1964) has shown that carbon tetrachloride, chloroform and several other compounds react with a s-cis-l,5-cyclo-octadiene by a free-radical transannular 1,5-cyclo-addition to give derivatives of bicyclo-[3,3,0]octane. He suggested that the cyclo-addition may occur by a concerted reaction in which the configuration of the diene is such that the two double bonds lie in close proximity, or alternatively by a step-wise reaction which involves a free-radical addition across the ring. 

Other examples of favored formation of cyclobutanes include photocycloadditions of tri-fluoromethyl-substituted coumarins with dienes,and of 5-(trifluoromethyl)-l,3-dioxin-4-ones, e.g. 3, with alkenes, " - - " as well as intramolecular photocycloadditions, such as those of bicyclo[2.2.2]octadiene and tricyclononadiene derivatives. 

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. ... 

The results of halogenation remain unchanged if reactions proceed in the dark, with addition of catalysts or inhibitors of radical processes. These data, as well as the strict regiospecificity on addition of mixed halogens (in the derivatives of bicyclo[3,2,l]octadienes the more electropositive halogen turns out to be on C ) corroborate the ionic character of the reactions studies. 

Gold(I) catalysis has been reported to convert cyclopentenes to cyclohexadienes and involves ring expansion and a [l,2]-alkynyl shift. It is thought to be initiated by the cleavage of the bridging C-C bond and the proposed allyl-gold cation intermediate is trapped with alcohol to give bicyclo[3.2.1]octadiene and tricyclo[3.2.1.0 ]octane derivatives (Scheme 110). ° ... 

The condensation, reduction, cyclisation and methylation steps shown above result in an a-methoxy-y-pyrone unit appended to a linear polyketide-derived side-chain of varying degrees of reduction. However, the majority of y-pyrone-containing natural products isolated from sacoglossan molluscs do not possess linear side-chains, instead exhibiting complex carbon frameworks commonly characterised by cyclic motifs. For example, 9,10-deoxytridachione (2) [13] possesses a 1,3-cyclohexadiene unit, whilst ocellapyrone A (5) is endowed with a bicyclo[4.2.0]octadiene appendage (Fig. 1.1). 

Since the work reported by Carreira and coworkers [36] on the synthesis and application of other chiral-bridged dienes containing the bicyclo[2.2.2]octadiene scaffold, Hayashi s group [40] has developed further these diene-type ligands and applied them successfully in the 1,4-addition of phenylboronic acids to unsaturated enones. Some of the bicyclo[2.2.2]octadiene ligand derivatives and their products can be seen in Scheme 5.11. 

In 1968, Tobey and Law reported on the intriguing reaction of furan, substituted furans, and cyclopentadiene with both tetrachloro- and tetrabromocyclo-propene (TBCP). The two unsaturated systems reacted smoothly to directly produce cycloheptanoid systems, the products of a formal [4-i- 3]-cycloaddition reaction. The authors proposed in their early manuscripts that the tetrahalocy-clopropenes underwent an initial thermal Diels-Alder cycloaddition to produce the cyclopropyl norbornene derivatives la and lb (Figure 2). However, these workers were unable to isolate or characterize the primary cycloadducts and instead observed a product which had spontaneously rearranged by way of a halogen atom migration to yield the bicyclo[3.2.1]octadiene nucleus 2a and 2b. 

Bicyclo[2.2.2]octadiene-fused porphyrins 44 involving core-modified ones were prepared by the common preparation methods of porphyrin syntheses such as cyclic tetrameriza-tion, [3 + 1], and [2 + 2] methods, and were converted to tetrabenzo derivatives 45 by heating (Scheme 15.6). Because synthesis of the quadruply BCOD-fused porphyrins was thought to be more difficult than those of singly, doubly,... 

In the case of 21,23-dithiaporphyrin derivative 45h, opp-21,23-dithiadibenzoporphyrin opp-Alh was predominantiy formed during the fragmentation (Scheme 15.8) [31]. In the case of 21 -thiaporphyrin derivative 45g, an ethylene molecule was expelled selectively from the bicyclo[2.2.2]octadiene moiety adjacent to the thiophene part to give 21-thiabenzo [( jporphyrin 46g and then 21-thiabenzo[g,g ]porphyrin derivative opp-Alg. In these cases, the last ethylene extrusion occurred from 200 °C and proceeded very slowly [32]. 

Ikeda, H., Takasaki, T., Takahashi, Y, Konno, A., Matsumoto, M., Hoshi, Y, Aoki, T., Suzuki, T, Goodman, J., and Miyashi, T, Photoinduced electron-transfer Cope rearrangements of 3,6-diaryl-2,6-octadienes and 2,5-diaryl-3,4-dimethyl-l,5-hexadienes stereospecificity and an unexpected formation of the bicyclo[2.2.0]hexane derivatives,/. Org. Chem., 64,1640, 1999. 

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