Octadienes cyclic

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. 

Cyclopolymerization of Nonconjugated Dienes. Cyclopolymerization is an addition polymerization that leads to introduction of cyclic structures into the main chain of the polymer. Nonconjugated dienes are the most deeply studied monomers for cyclopolymerization and for cyclocopolymerizations with alkene monomers 66 In general, (substituted and unsubstituted) dienes with double bonds that are linked by less than two or more than four atoms cannot undergo efficient cyclization and result in crosslinked materials.12 In fact, efficient cyclopolymerization processes have been described, for instance, for a,oo-dienes like 1,5-hexadiene, 2-methyl-l,5-hexadiene, 1,6-heptadiene, and 1,7-octadiene,67 73 which lead to formation of homopolymers and copolymers containing methylene-1,3-cycloalkane units. 

Reaction of iodine with non-conjugated dienes has been applied to the synthesis of cyclic compounds100. Although the reactions of 1,5-hexadiene, 1,6-heptadiene and 1,7-octadiene with I2 in CCI4 gave exclusively products arising from addition to the two double bonds, the introduction of dialkyl substituents into the 4-position of 1,6-heptadiene completely changed the reaction course in favor of cyclization (equation 85). 

Bicyclo[4,2,0]octene isomerizes smoothly to yield 1,3-cyclo-octadiene only at temperatures appreciably higher than are necessary for the mono-cyclic cyclobutenes. A study of this reaction in the gas phase in the temperature range 235 to 285° C yielded the Arrhenius equation... 

Cyclic olefins and diolefins form much more aerosol than 1-alkenes that have the same number of carbon atoms (for example, cyclohexene 1-hexene, and 1,7-octadiene 1-octene). The same effect of chain length and double-bond position is observed for diolefins (1,7-octadiene > 1,6-heptadiene > 1,5-hexadiene, and 1,7-octadiene 2,6-octadiene). Heavier unsaturated cyclic compounds, such as indene and terpenes, form even more aerosol. 

Terminal dienes gave slightly different results. Both cyclic and linear enol silyl ethers were produced in the reaction of 1,5-hexadiene, whereas for 1,7-octadiene only the straight chain E and Z isomers were produced. In neither case is the branched product observed.106... 

The next homolog in the cyclic series, 1,3,5-cyclooctatriene, also closes in a readily reversible transformation to bicyclo[4.2.0]octadiene (Equation 12.63). Cope and his collaborators reported this valence isomerization in 1952. They were able to separate the isomers, which revert to the equilibrium mixture of 85 percent 51 and 15 percent 52 on heating at 100°C for 1 hr.113 Huisgen has reported activation parameters of A Hi = 26.6 kcal mole-1, AS = — 1 cal... 

Simplified preparation. 9-BBN (dimeric) can be prepared in excellent yield (88%) and high purity by cyclic hydroboration of 1,5-octadiene with BH3 S(CH3)2 in monoglyme (1,2-dimethoxyethane) as the solvent, in which dimeric 9-BBN has very low solubility. One crystallization from this solvent gives large needles melting at... 

Presented in Table 9 are examples of Type IV reactions, cyclic monoole-fins reacting with acyclic olefins. 1,6-Heptadiene, 1,7-octadiene, and 1,9-de-cadiene were produced when cyclopentene, cyclohexene, and cyclooctene were cleaved with ethylene. A tridecadiene was synthesized from cyclopentene and 1-octene. 

An equivalent reaction has been achieved via the treatment of hydroborated bisalkenes with alkaline silver nitrate solution (Table 1.4).22,23 This method has been used to synthesize a number of small and medium-size carbocyclic rings in moderate to good yield. The selectivity for terminal cyclization observed for 1,6-heptadiene and 1,7-octadiene indicates that, in these cases, hydroboration of each of the alkenes occurs independently to yield acyclic boranes. It has, however, been found that both cyclic and acyclic boranes react under these conditions to yield the ring-closed products (Scheme 1.3). 

One of the most versatile applications of [Os]-anisole chemistry is the efficient generation of complex polycyclic systems. Through the application of a variety of methodologies, anisole complexes have been used to generate a number of cyclic arrangements, including a bi-cyclo[2.2.2]octadiene, decalins, tetralins, and tricyclic arrays. 

Three molecules of butadiene can be combined into 1,5,9-cyclododecatriene, using typical Ziegler-type catalysts. New TT-complex catalysts have been developed by which it is possible to direct the synthesis at will in direction of a trimerization or dimerization. 1,5-Cyclo-octadiene or 1,5,9-cyclododecatriene can be obtained in 95% yields. The catalysts can be isolated and are mostly crystalline—for instance, Ni-(0)-[P(CQH5)3]4 It has been possible to isolate a definite intermediate of the trimerization, the structure of which has been determined. Some reactions of this intermediate elucidate the mechanism of the trimerization. The cyclic olefins obtained from butadiene are valuable starting materials for the production of a-co difunctional compounds. 

Thermal cyclooligomerizations of olefins and alkynes require severe and often dangerous reaction conditions and the yields of cyclic products are usually very low. Acetylene ean be trimerized to benzene at 500 °C [1] and butadiene (BD) dimerizes at 270 °C and under high pressure to give small amounts of 1,5-cyclo-octadiene [2]. Reppe s discovery in 1940 that acetylene can be cyclotetramerized to cyclooctatetraene (COT) using a nickel catalyst [3] shows that transition metals can act as templates for the synthesis of cyclic hydrocarbons from acetylenic or olefinic building blocks (Scheme 1). 

Diradicals, including 1,3- and 1,4-types incorporating the cyclopropylmethyl unit 39 and 40, have been generated from ketones, cyclic diazenes, and in various other ways (see Section 2.4.1.5.2.7.). The intra- and intermolecular reactions of the 2-(spiro[2.5]octadien-6-yl)ethyl diradical 41 lead to some novel products. ... 

Octadiene and higher a,co-dienes with 1 1 HjB-THF leads to polymeric material. Low yields of cyclic products are also obtained in the hydroboration of mixed dienes, e.g., 4-vinylcyclohexene or limonene (see Table 7), but 1,5-cyclooctadiene undergoes cyclic hydroboration in high yield. A mixture of 9-borabicyclo[3.3.1] nonane (9-BBN) and 9-borabicyclo[4.2.1]nonane is formed. Other intermediates are also observed by B NMR. Upon heating, the latter compound is transformed " to the more thermodynamically stable 9-BBN ... 

Ortho addition is the favoured mode of photochemical addition of alkenes to hexafluorobenzene and this has now been extended to the addition of the dienes 1,4-octadiene and 1,3-hexadiene. Ortho adducts are also formed in the irradiation of pentafluoroalkoxy-benzenes with cyclic alkenes the reaction is regioselective and... 

Ethenolysis of cycloalkenes is a convenient route for production of certain polyunsaturated compounds. Shell have developed a process for the manufacture of a,w-diolefins via ethenolysis of cyclic olefins (the reverse of Eq. 4) [21,22]. Thus, 1,5-hexadiene and 1,9-decadiene were produced via ethenolysis of cyclo-octadiene and cyclooctene, respectively (Eqs. 7a,b). 

The stabilized cyclic olefin insertion product explains why the reaction stops with the insertion of only one ethylene group. The carboxylation product of crotyl chloride, 3-pentenoic acid, and 2,6-octadiene (from the coupling of two crotyl chloride molecules together) also forms. 

The aldehydes and ketones most commonly used are benzaldehyde, acetaldehyde, formaldehyde, and acetone. However, -butyraldehyde, n-propionaldehyde, salicylaldehyde, p-tolualdehyde, and 2-furaldehyde have also been employed. A number of unsaturated aldehydes, for example, 3,7-dimethyl-2,6-octadienal (citral) and cinnamaldehyde, have yielded cyclic acetals. Acetals have been prepared from 2-butanone, cyclohexanone, and glyoxal. ... 

The double bonds of cyclopentadiene are constrained in a planar cisoid conformation and this diene therefore reacts easily with a variety of dienophiles. 1,3-Cyclohexadiene is also reactive, but with an increase in the size of the ring, the reactivity of cyclic dienes decreases rapidly. In large rings, the double bonds can no longer easily adopt the necessary coplanar configuration because of non-bonded interaction of methylene groups in the planar molecule. Cis,cis- and cis,trans-l,3-cyclo-octadienes form only copolymers when treated with maleic anhydride and cis,cis- and cis,trans-1,3-cyclodecadienes similarly do not form adducts with maleic anhydride. Dienes with 14- and 15-membered rings react with dienophiles but only vmder relatively severe conditions. 

On an unspecified supported palladium catalyst at 323 K, 1,5-cyclo-octadiene isomerised to the 1,3-form at about the same rate as it was hydrogenated 5tot was about 90%, and some mathematical modelling was attempted. Other cyclic dienes have also been examined. ... 

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