Cis-cyclooctene

The reaction of thiocyanogen (N=CS—SC=N) with cis cyclooctene proceeds by anti addition... 

Cyclooctatetraene is relatively stable but lacks the special stability of benzene Unlike benzene which we saw has a heat of hydrogenation that is 152 kJ/mol (36 kcal/mol) less than three times the heat of hydrogenation of cyclohexene cycloocta tetraene s heat of hydrogenation is only 26 kJ/mol (6 kJ/mol) less than four times that of CIS cyclooctene... 

It is still not clear whether steric constraints can modify the magnitude of bromine bridging. There is at least one example that suggests that this is possible. Non-additive kinetic substituent effects and cis-dibromoadducts imply that the intermediate of cis-cyclooctene bromination in methanol is a /J-bromocarbocation (Dubois and Fresnet, 1974). 

Polymerization of cis-cyclooctene with the cyclic ruthenium initiator LXVIII produces cyclopolyoctenamer LXIX as the monomer undergoes ring opening and insertion into the ruthenium-carhene bond of the initiator [Bielawski et al., 2002]. Unlike most ROMPs... 

One-Step Olefin-to-Allene Conversion of cis-Cyclooctene to 1,2-Cyclononadiene. 1... 

The compound selected to illustrate this procedure is Cr(rj6-C6H5C02CH3)(C0)2(CNC0C6H5). Compounds of this type have already been shown to be active catalytically but sometimes with a different activity from that of the well-known parent tricarbonyl derivatives.4 For example, reaction of cis-cyclooctene with Cr( 6-l-C02CH3-2-CH3C6H4)(C0)2-(CNCOC6H5) for 15 h at 60 °C in CCl4-tetrahydrofuran (THF) solution affords 60% conversion into l-chloro-2-(trichloromethyl)cyclooctane.2... 

The catalytic performance of the supported bimetallic nano-particles in the hydrogenation of unsaturated molecules was tested on a wide variety of unsaturated species hex-l-ene, phenyl acetylene, diphenyl acetylene, trans-stilbene, cis-cyclooctene and D-limonene. The highly efficient hydrogenation of hex-1 -ene was accompanied by the isomerisation reaction to cis-and trans-hex-2-ene, which were subsequently hydrogenated (albeit at a much slower rate) as reaction ensued. 

Vic-diols can thus be easily converted to alkenes through their reaction with A, A -thiocarbonyldimidazule. The reported synthesis of trans-cyclooctene is illustrative of the method [219]. It should be noted that continuous elimination of rrans-cyclooctene by a stream of argon was necessary to avoid isomerization to the cis isomer. The conversion of cis-cyclooctene to ww-cyclooctene through a trithiocarbonate is described in the same paper. 

Photoinduced ring cleavage also occurs readily in heterocyclic systems containing both oxygen and nitrogen. A series of dihydro-oxadiazinones, for example, undergo decomposition, and the results obtained parallel those observed on thermal decomposition cis- and Jraras-stilbene are obtained from the diphenyl derivative (71), whereas cis-cyclooctene is the major product of photolysis of the fused cyclooctane (72).62... 

Figure 1 Originally proposed structure (I) and definitive structure (II) of the ortho photocycloadduct from benzene and cis-cyclooctene.

The formation of a derivative of cyclooctatriene had earlier been observed by Bryce-Smith et al. [153] during their investigation of the photoaddition of cis-cyclooctene to hexafluorobenzene. One of the products of this reaction is 2,3,4,5,6,7-hexafluorobicyclo[6.6.0]tetradeca-2,4,6-triene, formed by ring opening of the primary ortho adduct. The ortho adducts derived from hexafluorobenzene and its derivatives seem especially prone to undergo this isomerization (see below), but for derivatives of benzene itself, the reaction was not often reported prior to 1987. The study by Mirbach et al. [114] has been referred to earlier and Atkins et al. [120] mention in a note that endo-ortho adducts might be converted... 

Fig. 31 Synthesis of cyclic PE using ROMP of cis-cyclooctene and hydrogenation...

In cyclic alkenes such as cyclohexene and cycloheptene trans addition was also highly stereoselective [7]. However, cis cyclooctene afforded both cis and trans adducts in the ratio 1 3 in the presence of oxygen 1,4-dichlorides were also formed [8]. In cyclodecenes, both cis and trans, the main product was the allylic chloride, with some formation of transannular dichlorides [9]. In some substrates with an exocyclic double bond, such as methylene cyclobutane, only (dichloroiodo)benzene was suitable for a clean addition [10]. 

In the attempted preparation of cyclooctyne (14)10) from 1-chlorocyclooctene (12) using lithium piperidide as a base only l-(piperidyl)-cis-cyclooctene (13) was obtained 10). This result was interpreted by assuming (14) as an intermediate which then adds lithium piperidide to yield (13). 

However, with the proper starting material, base and conditions this elimination reaction can be used for an efficient synthesis of (14) in good yield by applying sterically hindered lithium diisopropylamide as a base and 1-bromo-cis-cyclooctene (15) in excess U). 

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