Cyclooctadiene, reaction

Elimination of Pd (II) hydride where the origin of the hydrogen is Ha, Hb, or He would give a strain-free double bond. However, there is another possible explanation for this stability. If the original oxypalladation is cis and if the Pd(II)-hydride elimination is also cis, then He is trans to the Pd(II) and cannot be eliminated. Furthermore, if molecular models are made, one can see that if square-planar Pd (II) is bonded to one carbon and also coordinated to the double bond, then the cyclooctene ring must be twisted so that Ha and Hb are not in position for a cis elimination. Any other combination of cis or trans addition and cis or trans elimination does not give the desired result. Recently it was reported that the adduct from PdCL and 1,5-cyclooctadiene (Reaction 72) does in fact have cis stereochemistry (Anderson, C. B., Burreson, B. J., Chem. IncL 1967, 620). 

A bicyclic peroxide was isolated in 1.8% yield by HPLC of the bromodemercuration product, and was identified as a single diastereoisomer of 2,4-dibromo-6,7-dioxa-bicyclo[3,2.1]octane 57 with the iransjrans- or cis,cis-configuration. By analogy with the cyclooctadiene reactions, formation of the other two diastereoisomers of 57 can be expected, but although additional peroxides with similar HPLC characteristics were detected, they were not identified. Thus the presence of [2.2.2]-compounds cannot be ruled out, and no comment can be made on the regioselectivity of the dioxabicyclization. 

Cation-radicals, stabilized in zeolites, are excellent one-electron oxidizers for alkenes. In this bimolecular reaction, only those oxidizable alkenes can give rise to cation-radicals, which are able to penetrate into the zeolite channels. From two dienes, 2,4-hexadiene and cyclooctadiene, only the linear one (with the cylindrical width of 0.44 nm) can reach the biphenyl cation-radical or encounter it in the channel (if the cation-radical migrates from its site toward the donor). The eight-membered ring is too large to penetrate into the Na-ZSM-5 channels. The cyclooctadiene can be confined if the cylindrical width is 0.61 nm, however the width of the channels in Na-ZSM-5 is only 0.55 nm. No cyclooctadiene reaction with the confined biphenyl cation-radical was detected despite the fact that, in solution, one-electron exchange between cyclooctadiene and (biphenyl) proceeds readily (Morkin et al. 2003). 

Metathesis technology enables the synthesis of many other high-purity olefins for the speciality chemicals market. Phillips have produced multi-ton quantities of hexa-1,5-diene via ethenolysis of cyclooctadiene and cyclododecatriene over a W03/Si02 catalyst reaction (9). High yields of deca-1,9-diene can be obtained from ethenolysis of cyclooctene (obtained by partial hydrogenation of readily available cyclooctadiene), reaction (10). Similarly, tetradeca-1,13-diene can be obtained via ethenolysis of cyclododecene (obtained from cyclododecatriene) (Banks 1982, 1984a). 

In recent years, a wide variety of alkene and related compounds have been prepared. The most stable of these seem to be formed by moleeules eontaining two double bonds that are so located that they can both bond to the same metal. One molecule of this type is cyclooctadiene, reaction (7). Alkene eompoimds are normally prepared by the direct reaction of an alkene with a metal salt or complex. 

The cyclohexadiene derivative 130 was obtained by the co-cyclization of DMAD with strained alkenes such as norbornene catalyzed by 75[63], However, the linear 2 1 adduct 131 of an alkene and DMAD was obtained selectively using bis(maleic anhydride)(norbornene)palladium (124)[64] as a cat-alyst[65], A similar reaction of allyl alcohol with DMAD is catalyzed by the catalyst 123 to give the linear adducts 132 and 133[66], Reaction of a vinyl ether with DMAD gives the cyclopentene derivatives 134 and 135 as 2 I adducts, and a cyclooctadiene derivative, although the selectivity is not high[67]. 

The photosensitized dimerization of isoprene in the presence of henzil has been investigated. Mixtures of substituted cyclobutanes, cyclohexenes, and cyclooctadienes were formed and identified (53). The reaction is beheved to proceed by formation of a reactive triplet intermediate. The energy for this triplet state presumably is obtained by interaction with the photoexcited henzil species. Under other conditions, photolysis results in the formation of a methylcydobutene (54,55). 

The reaction of a mixture of 1,5,9-cyclododecatriene (CDT), nickel acetylacetonate [3264-82-2], and diethylethoxyalurninum in ether gives red, air-sensitive, needle crystals of (CDT)Ni [12126-69-1] (66). Crystallographic studies indicate that the nickel atom is located in the center of the 12-membered ring of (CDT)Ni (104). The latter reacts readily with 1,5-cyclooctadiene (COD) to yield bis(COD) nickel [1295-35-8] which has yellow crystals and is fairly air stable, mp 142°C (dec) (20). Bis(COD)nickel also can be prepared by the reaction of 1,5-COD, triethylaluminum, and nickel acetylacetonate. 

Use of HRh(CO)[P(CgH )2]3 as the catalyst and an excess of triphenylphosphine improves the y P ratio. For example, reaction of triethoxysilane with allylamine of equivalent moles at 150°C for 10 h, yields the y-form product ia more than 70% and the y P ratio is 26. Compared with this, when H2PtCl3 is used as the catalyst, the y P ratio is 4 (41). Furthermore, when Rh[(p.-P(C3H3)2-(cyclooctadiene)]2 is used as the catalyst, the yield of y-form product is selectively increased to 92% and that of P-form product is decreased to 1.1% (42). 

A fascinating series of cyclodimeri2ation or cyclotrimeri2ation reactions was first observed in the labs of Wilke to produce 1,5-cyclooctadiene... 

The thermal behavior of A and B above 150°C has been studied. Both in the gas phase and in solution, each compound yields a 3 5 mixture of ,Z-l,5-cyclooctadiene (C) and Z,Z-l,5-cyclooctadiene (D). When hexachlorocyclopentadiene is present, compound E is found in place of C, but the amount of D formed is about the same as in its absence. Formulate a description of the thermolysis mechanism that is consistent with these facts and the general theory of thermal electrolytic reactions. 

Interestingly, the intramolecular cycloadduct 97 (15%) was obtained from the reaction of 3,4-dicyanofuroxan with 1,5-cyclooctadiene. In contrast, with nor-bomadiene only intermolecular products 98 (30%) and 99 (14%) were obtained (85T727) (Scheme 48). 

An interesting addition reaction of sulfur dichloride has been discovered that allows the preparation in good yield of bridged cyclic sulfides from cyclic dienes. Two examples of the reaction have been described (cyclo-octadiene and in the other 1,5-cyclooctadiene. The former sequence is shown in the scheme. The experimental details of the latter sequence are given below. 

Photolytic reactions of dienes frequently give complex mixtures of rearranged products. Described here, however, is a photolytic isomerization of 1,5-cyclooctadiene (present in solution, in part, as a complex with cuprous chloride) that affords a good yield of one product. 

Benzoyl fluoride, 46,3 Benzoy lhydrazine, 46, 85 Benzoyl peroxide, as catalyst for reaction of chloroform with as,as 1,5 cyclooctadiene, 47, 11 reaction with diethyl ethylmalonate, 46, 37... 

Mutual metathesis of a cyclic and an acyclic alkene provides still more possibilities in synthesizing organic compounds. For instance, cycloalkenes are cleaved by ethene into a,co-dienes. The reaction of 1,5-cyclooctadiene with ethene gives 1,5,9-decatriene (18) norbornene reacts with 2-butene to yield 1,3-dipropenylcyclopentane (30) ... 

Steric factors may also be important in situations where alternative modes of reaction are available. Dall Asta (44) examined the ring-opening polymerization of 3-methyl-m-cyclooctene. By infrared analysis of the product formed, he obtained quantitative information about the occurrence of head-to-head and head-to-tail successions. More than 90% of the links in the polymethyloctenamer were of the head-to-tail type, but the sterically more hindered and, therefore, unfavored head-to-head links were also observed (about 5%). Ofstead (39) investigated the ring-opening polymerization of some 1,5-cyclooctadienes substituted at one of the two... 

Various 1,5-dibromoquinoxalines have been polymerized by organometallic dehalogenation (Fig. 5.41). The reaction takes place in DMF with (1,5-cyclooctadiene) Ni(0) in the presence of 2,2 -bipyridine at 60°C for 48 h.168169 Highly conjugated acenaphthene quinoxalines were prepared by this procedure and exhibit photoluminescence peaks at 400 and 514 nm.170... 

Kinetic studies using 1,9-decadiene and 1,5-hexadiene in comparison widi catalyst 14 and catalyst 12 demonstrate an order-of-magnitude difference in their rates of polymerization, widi 14 being the faster of the two.12 Furdier, this study shows diat different products are produced when die two catalysts are reacted widi 1,5-hexadiene. Catalyst 14 generates principally lineal" polymer with the small amount of cyclics normally observed in step condensation chemistry, while 12 produces only small amounts of linear oligomers widi die major product being cyclics such as 1,5-cyclooctadiene.12 Catalyst 12, a late transition metal benzylidene (carbene), has vastly different steric and electronic factors compared to catalyst 14, an early transition metal alkylidene. Since die results were observed after extended reaction time periods and no catalyst quenching or kinetic product isolation was performed, this anomaly is attributed to mechanistic differences between diese two catalysts under identical reaction conditions. 

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