Norbornene bicyclo

Ring-opening was not restricted just to norbornenes bicyclo[3.3.0]octenes, cyclooctene and a functionalised cyclobutene were all reactive substrates for these reactions. 

Studies by the submitters have indicated that the procedure reported here is the preferred method for the preparation of bicyclo[3.2.1]octan-3-one. It employs readily available, inexpensive reagents, and the overall yield is good. In addition, the method can be used for the synthesis of the difficultly accessible next higher homologues of bicyclo[2.2.2]oct-2-ene as well as for derivatives of norbornene. Bicyclo[3.2.2]nonan-3-one and l-methylbicyclo[3.2.1]octan-3-one have been prepared by a similar route6 in 60% and 47% yields, respectively (based on adduct). However, the preferred procedure for the formation of the dichlorocarbene adduct of bicyclo[2.2.2]oct-2-ene is that of Seyferth using phenyltrichloromethylmercury. Even in this case the overall yield is moderate (37%). 

Oxymercaration (2, 265-267 3. 194). Brown and Geoghegan have investigated the relative reactivities of a number of olefins in the oxymercuration reaction in a 20 80 (v/v) mixture of water and THF. The following reactivity is observed terminal disubstituted > terminal monosubstituted > internal disubstituted > internal trisub-stituted > internal leirasubstitu ted. Thus steric factors play a major role in the reactivity of olefins. Increased substitution on the double bond and increased steric hindrance at the site of hydroxyl or mercury substituent attachment decrease the rate of reaction. In the case of olefins of the type RCH CHR, cts-oleiins are more reactive than the corre.sponding rra/i.s-olefins. Inclusion of the double bond in ring systems causes a moderate rate increase which varies somewhat with structure cyclohcxenc > cyclo-pentenc cyclooctene norbornene bicyclo[2.2.2]-octene-2. 

The binding of norbornene to a triosmium cluster may model the coordination of this molecule to metal surface sites. Reactions of the lightly stabilized cluster Os3(CO)io(NCMe)2 with norbornene (bicyclo[2.2.1]hept-2-ene) led... 

Besides of ethene also other alkenes react with carbon dioxide in the presence of nickel(0) complexes. Some examples are given in Figure 6. Hexenes lead to different isomeric heptanoic acids, styrene reacts to cynnamic acid and norbornene (bicyclo 2.2.1 heptene) gives the exo-norbornane-2-carboxylic acid in 95 % yield [5,12,13]. Nor-bornadiene which contains two isolated double bonds reacts to a monoaddition product whose decomposition with hydrochloric acid yields a mixture of six chloronorbornanecarboxylic acids with the chloro-and carboxy-substituents both in exo- and in endo-positions [14]. 

From norbornene, bicyclo[3,2,l]oct-2-ene derivatives, and 1-methyl-1,2-dihydroquinoline, PTC proved an efficacious method of dihalogeno-cyclopropanation after other methods had failed or had given very poor yields. With ap-unsaturated esters and nitriles which bear an a-substituent, the PTC method gives cycloaddition. (From methyl acrylate, acrylonitrile, or vinyl acetate there is only nucleophilic addition across the double bond.) From buta-1,3-diene and dichlorocarbene generated by PTC, an improved yield of... 

Braun, M., Christl, M., Peters, E.M., and Peters, K., Photochemical reactions of chloranil with norbornene, bicyclo[2.1.1]hex-2-ene and cyclopentene. A novel intermolecular photocycloaddition,/. Chem. Soc., Perkin Trans. 1, 2813, 1999. 

With the growing interest for the polynorbomene, photoresist polymer, and cyclic olefin copolymer, the synthesis norbornene or bicyclo[2,2,l]-2-heptene (NBN) has drawn significant attention because it is one of the most important precursor for these materials. Norbornene is produced by the reaction between ethylene and cyclopentadiene (CPD) via the Diels-Alder condensation process at elevated temperature and pressure [1,2]. 

The first well-defined Ru alkylidene metathesis initiator, (231), was reported by Grubbs et al. in 1992.632 This complex initiates the ROMP of norbornene and other highly strained monomers such as bicyclo[3.2.0]hept-6-ene.633 Examination of alternative ligands634-636 led to the development of more active initiators, in particular (232)637 and (233).638-640... 

We have reported the first example of a ring-opening metathesis polymerization in C02 [144,145]. In this work, bicyclo[2.2.1]hept-2-ene (norbornene) was polymerized in C02 and C02/methanol mixtures using a Ru(H20)6(tos)2 initiator (see Scheme 6). These reactions were carried out at 65 °C and pressure was varied from 60 to 345 bar they resulted in poly(norbornene) with similar conversions and molecular weights as those obtained in other solvent systems. JH NMR spectroscopy of the poly(norbornene) showed that the product from a polymerization in pure methanol had the same structure as the product from the polymerization in pure C02. More interestingly, it was shown that the cis/trans ratio of the polymer microstructure can be controlled by the addition of a methanol cosolvent to the polymerization medium (see Fig. 12). The poly(norbornene) prepared in pure methanol or in methanol/C02 mixtures had a very high trans-vinylene content, while the polymer prepared in pure C02 had very high ds-vinylene content. These results can be explained by the solvent effects on relative populations of the two different possible metal... 

Thus, the oxidation potential of the former type of diene (limonene) is substantially the same as that of the corresponding monoolefin (1-Me-cyclohexene), whereas norbor-nadiene and bicyclo[2.2.2]octadiene show much lower oxidation potentials than those of norbornene and cyclohexene. 

Dieses Modell ist auch auf die stereospezifische Hydroborierung von 3-Methylcydopenten und Norbornen anwendbar, wahrend es im Falle des Bicyclo-[2,2,2]-octens zu versagen scheint 314). 

A vinylcyclopropylidene to cyclopentenylidene isomerization evidently also taken place when 7,7-dibromo-bicyclo[4.1.0]hept-2-ene and 8,8-dibromo-bicyclo[5.1.0]-oct-2-ene are treated with methyllithium. The former compound is converted to 7-bromo-7-methyl-norbornene by intermolecular insertion into the C -Br bond of methyl bromide, whereas tetrahydropentalene is obtained from the latter [113]. 

Monomers with UV-absorbing functionality, such as shown in Figure 1.11 can be copolymerized with norbornene to have the UV-absorber bond to the polymeric backbone. (4-(Bicyclo[2.2.1]hept-5-en-2-ylmethoxy)-2-hydroxyphenyl)phenyl-methanone is prepared by first synthesizing 4-allyl-2-hydroxyphenyl-phenyl-methanone... 

Certain norbornene derivatives, for example, 5-(2-naphthalene-carbonyloxy)bicyclo[2.2.1 ]hept-2-ene or 5-(4-biphenylcarbonyloxy)-bicyclo[2.2.1]hept-2-ene produce a polymer that is effective in producing molded products with excellent transparency, low water absorption, and low birefringence (29). 

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