Bicyclooctadienes—

The drawback of the CVD method is eliminated in ROMP, which is based on a catalytic (e.g., molybdenum carbene catalyst) reaction, occurring in rather mild conditions (Scheme 2.3). A living ROMP reaction ofp-cyclophanc 3 or bicyclooctadiene 5 results in soluble precursors of PPV, polymers 4 [31] and 6 [32], respectively, with rather low polydispersity. In spite of all cis (for 4) and cis and trans (for 6) configuration, these polymers can be converted into aW-trans PPV by moderate heating under acid-base catalysis. However, the film-forming properties of ROMP precursors are usually rather poor, resulting in poor uniformity of the PPV films. 

Carreira et al. reported the kinetic resolution of branched allylic carbonates catalyzed by an iridium complex derived from a chiral [2.2.2]-bicyclooctadiene [48]. Reactions of allylic carbonates with phenol were run to 50% conversion of the carbonate, leaving unreacted allylic carbonate in high enantiomeric excess (Scheme 32). The phenyl ether products were also isolated in mid-to-high enantiomeric excess. 

Birch and Hutchinson have reported some of the addition reactions of cyclohexadienylamines with DMAD and have shown that the stability of the bicyclooctadienes formed in these reactions depends to a... 

Derivatives of 1,2-dihydroazocine are potentially available by valence isomerization of the 7-azabicyclo[4.2.0]octadiene system. Sulfonyl derivatives (71) of the latter have been prepared, but the equilibria with dihydroazocines lie completely on the side of the bicyclic isomers (71JOC435). On heating, the bicyclooctadienes rearrange to the acyclic tetraenes (73), presumably via the unstable dihydroazocines (72). 

From the cyclooctatriene - bicyclooctadiene equilibrium, it is possible to trap the structure containing the four-membered ring with dienophiles, e.g. maleic anhydride, including those cases where the bicyclic isomer is only present in small amounts. For example, the dimer of cyclooctatetraene 7 on reaction with maleic anhydride gives the 1 1 adduct 8 in refluxing benzene and the. n 7-tricyclo[4.2.0.02,5]oclane derivative 9 in refluxing toluene.62... 

Linear and cyclic diolefins form a variety of clusters with trirutheniumdodeca-carbonyl or the tetraruthenium carbonyl hydrides. These belong to the compound types H2Ru3(CO)9L [56] or HRu3(C0)gl/ [55]. Type [56] complexes are obtained from cyclopentadienes (27 7), cyclooctadienes (74), or bicyclooctadiene (146). 

Changing the anchoring atom from oxygen to carbon does not change the initial photochemistry of the unsaturated ketones. The rates of the subsequent thermal electrocyclic rearrangements are, however, changed substantially. The tri-fluoroacetyl substituent was chosen to maintain as strong a donor-acceptor interaction in the bicyclooctadienes as possible, as well as to maintain a lowest triplet. 

A synthesis of substituted phenanthrenes has been reported using the bicyclooctadienes (61) as starting material. The process makes use of the nucleofugal group on C-8 and follows the path outlined in Scheme 3. This involves a di-rr-methane bridging process followed by the collapse of the intermediate biradical (62). Normal di-Ti-methane behaviour is reported in the acetophenone-sensitized irradiation of the isoquinolinone derivative (63a). This yields the two products (64) and (65) as a 3 1 mixture in a total yield of 75%. An N-oxide derivative gave a brown polymer with little evidence for the formation of di-n-methane products. The influence of ring substituents was also studied for the derivatives (63b, d) and the results of this are shown in Scheme 4. The authors conclude that the cyclization process is under LUMO control. Irradiation of the dihydropyridine (66) affords the oxidised pyridine (67) as the major product. A minor product (68) is also formed by a di-ir- methane process. ... 

Synthesis of polysubstituted benzenes by a Diels-Alder reaction of cyclohexadienes with acetylenes, via bicyclooctadienes. 

Silicon, Germanium, Tin and Lead Bridgehead extrusion from bicyclooctadienes ... 

An important polymer in electrooptical applications is poly(phenylene vinylene) (PPV), which has alternating phenyl and vinyl groups. (Tne of the routes to this polymer starts with a substituted bicyclooctadiene that is polymerized using ROMP techniques to form a soluble, processable polymer. Heating the processed polymer results in elimination of two equivalents of acetic acid, which aromatizes the six-membered ring and completes the conjugation. 

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