5- Vinyl-2-norbomene

Diels-Alder Reactions. The important dimerization between 1,3-dienes and a wide variety of dienoplules to produce cyclohexene derivatives was discovered in 1928 by Otto Diels and Kurt Alder. In 1950 they won the Nobel prize for their pioneering work. Butadiene has to be in the j -cis form in order to participate in these concerted reactions. Typical examples of reaction products from the reaction between butadiene and maleic anhydride (1), or cyclopentadiene (2), or itself (3), are <7 -1,2,3,6-tetrahydrophthaHc anhydride [27813-21 -4] 5-vinyl-2-norbomene [3048-64-4], and 4-vinyl-1-cyclohexene [100-40-3], respectively. 

They can be handled analogous to thermosetting resins, and thus the use of highly volatile comonomers, such as ethene or prop-ene is prohibitive. Instead, other vinyl monomers are used. A heat curable formulation uses a mixture of tetracyclododecene, 2-norbomene, 5-vinyl-2-norbomene, and divinylbenzene as reactive components (41). The mixture further contains 3,5-di-ferf-butylhy-droxyanisole as antioxidant and a hybrid catalyst system containing a zirconium based metathesis catalyst and a radical catalyst. The metathesis catalyst is benzylidene (l,3-dimesitylimidazolidin-2-yl-idene)(tricyclohexylphosphine)ruthenium dichloride and the radical catalyst is di-ferf-butyl peroxide. 

As was mentioned, cycloaddition of unactivated hydrocarbons, namely, that of cyclopentadiene, has practical significance. 5-Vinyl-2-norbomene is produced by the cycloaddition of cyclopentadiene and 1,3-butadiene546,547 [Eq. (6.96)] under conditions where side reactions (polymerization, formation of tetrahydroindene) are minimal. The product is then isomerized to 5-ethylidene-2-norbomene, which is a widely used comonomer in the manufacture of an EPDM (ethylene-propylene-diene monomer) copolymer (see Section 13.2.6). The reaction of cyclopentadiene (or dicyclopentadiene, its precursor) with ethylene leads to norbomene548,549 [Eq. (6.97)] 550... 

Norbornene 5-Phenyl-2-norbomene 5-Vinyl-2-norbomene 5-Ethylidene-2-norbomene... 

Recently, the development of commercial EPDMs with 5-vinyl-2-norbomene [3048-64-4] (5), a precursor in the synthesis of ENB, as third monomers has been reported, aiming at a higher vulcanization yield with peroxide curatives, relative to ENB- or DCPD-containing EPDMs (5) ... 

Copolymerizations of ethene with bicycUc olefins, such as 2,5-norbomadiene and 5-vinyl-2-norbomene, have been investigated with metallocene catalysts. The secondary groups do not interfere with metallocene copolymerizations, and postpolymerization functionalization makes it possible to synthesize functionalized polyolefins [133-135]. 

Hydrosilylation of norbornadiene (nbd) by chloro- or alkyl-hydrosilanes in the presence of Pd- or Mo-catalysts [178, 179] led to the corresponding silylnor-bornenes. Norbornenes with ethane spacer between bicyclic nuclear and silicon atom can be synthesized by hydrosilylation of 5-vinyl-2-norbomene [180],... 

Dimethylbut-l-ene (DB-1, Fluka, 98%) is distilled before use and stored under argon. The alkene (2mL DB-1) is added to the catalyst at room temperature and stirred. After 10 min the catalyst is separated from the liquid by filtration. Conversion is dose to equilibrium (92.8%). For 1-hexene (vinyl-norbomene) the conversion is 99 % after 10 min (4 h). 

TYPICAL COMONOMERS Ethene, propene, ethylidene norbomene (ENB) or dicyclopentadiene or (DCPD), 1,4 hexadiene (4,4 HD), or vinyl norbomene (VNB) or norbomadiene (NBD). ... 

Lipase-catalyzed enantioselective transesterification of 0-substituted-l,2-diols is another practical route for the synthesis of P-blockers. Lipase PS suspended in toluene catalyzes the transesterification of (63) with vinyl acetate to give the (5)-ester in 43% yield and >98% ee (78). The desired product, optically pure (R)-ttitylglycidol, is then easily obtained by treating the ester with alcohoHc alkaU. Moreover, Pseudomonas Hpase catalyzes the acylation of oxazohdinone (64) with acetic anhydride in very good yield and selectivity (74). PPL-catalyzed transesterification of a number of /n j -norbomene derivatives proceeds in about 30% yield and 92% ee (79,80). 

Abbreviations aapy, 2-acetamidopyridine Aik, alkyl AN, acetoniuile Ar, aryl Bu, butyl cod, 1,5-cyclooctadiene COE, cyclooctene COT, cyclooctatetraene Cp, cyclopentadienyl Cp , penta-methylcyclopentadienyl Cy, cyclohexyl DME, 1,2-dimethoxyethane DME, dimethylformamide DMSO, dimethyl sulfoxide dmpe, dimethylphosphinoethane dppe, diphenylphosphinoethane dppm, diphenylphosphinomethane dppp, diphenylphosphinopropane Et, ethyl Ec, feirocenyl ind, inda-zolyl Me, methyl Mes, mesitylene nb, norbomene orbicyclo[2.2.1]heptene nbd, 2,5-norbomadiene OTf, uiflate Ph, phenyl PPN, bis(triphenylphosphoranylidene)ammonium Pi , propyl py, pyridine pz, pyrazolate pz, substituted pyi azolate pz , 3,5-dimethylpyrazolate quin, quinolin-8-olate solv, solvent tfb, teti afluorobenzobaiTelene THE, tetrahydrofuran THT, tetrahydrothiophene tmeda, teti amethylethylenediamine Tol, tolyl Tp, HB(C3H3N2)3 Tp , HB(3,5-Me2C3HN2)3 Tp, substituted hydrotiis(pyrazol-l-yl)borate Ts, tosyl tz, 1,2,4-triazolate Vin, vinyl. 

Copper(II) triflate has also been used for the carbenoid cyclopropanation reaction of simple olefins like cyclohexene, 2-methylpropene, cis- or rran.y-2-butene and norbomene with vinyldiazomethane 2 26,27). Although the yields were low (20-38 %), this catalyst is far superior to other copper salts and chelates except for copper(II) hexafluoroacetylaeetonate [Cu(hfacac)2], which exhibits similar efficiency. However, highly nucleophilic vinyl ethers, such as dihydropyran and dihydrofuran cannot be cyclopropanated as they rapidly polymerize on contact with Cu(OTf)2. With these substrates, copper(II) trifluoroacetate or copper(II) hexafluoroacetylaeetonate have to be used. The vinylcyclopropanation is stereospecific with cis- and rra s-2-butene. The 7-vinylbicyclo[4.1.0]heptanes formed from cyclohexene are obtained with the same exo/endo ratio in both the Cu(OTf)2 and Cu(hfacac)2 catalyzed reaction. The... 

The resulting complexes can be effectively employed as single component catalysts to homopolymerize ethylene or copolymerize ethylene with acrylates [50, 51] and a variety of other polar monomers including vinyl ethers, [51,52] vinyl fluoride [53], iV-vinyl-2-pyrrolidinone, and AMsopropylacrylamide [54], In fact, the resulting catalysts are so robust that they can be used as single component catalysts in aqueous emulsion homo-polymerization of ethylene and copolymerization of ethylene with norbomenes and acylates [55]. 

It was found that 2-propenyloxymagnesium bromide reacts much more readily with nitrile oxides than other known dipolarophiles of electron-deficient, electron-rich, and strained types, including 3-buten-2-one, ethyl vinyl ether, and norbomene, respectively (147). Therefore, this BrMg-alkoxide is highly effective in various nitrile oxide cycloaddition reactions, including those of nitrile oxide/Lewis acid complexes. 

The results of the olefin oxidation catalyzed by 19, 57, and 59-62 are summarized in Tables VI-VIII. Table VI shows that linear terminal olefins are selectively oxidized to 2-ketones, whereas cyclic olefins (cyclohexene and norbomene) are selectively oxidized to epoxides. Cyclopentene shows exceptional behavior, it is oxidized exclusively to cyclopentanone without any production of epoxypentane. This exception would be brought about by the more restrained and planar pen-tene ring, compared with other larger cyclic nonplanar olefins in Table VI, but the exact reason is not yet known. Linear inner olefin, 2-octene, is oxidized to both 2- and 3-octanones. 2-Methyl-2-butene is oxidized to 3-methyl-2-butanone, while ethyl vinyl ether is oxidized to acetaldehyde and ethyl alcohol. These products were identified by NMR, but could not be quantitatively determined because of the existence of overlapping small peaks in the GC chart. The last reaction corresponds to oxidative hydrolysis of ethyl vinyl ether. Those olefins having bulky (a-methylstyrene, j8-methylstyrene, and allylbenzene) or electon-withdrawing substituents (1-bromo-l-propene, 1-chloro-l-pro-pene, fumalonitrile, acrylonitrile, and methylacrylate) are not oxidized. 

F. Blank and C. Janiak, Metal catalysts for the vinyl/addition polymerization of norbomene, Coord. Chem. Rev., 253(7-8) 827-861, April 2009. 

Irradiation of the epoxy dinitrile 90 in a solution of acetonitrile formed the stabilized ylide 91 that was trapped with ethyl vinyl ether, producing both exo and endo adducts 92 and 93 in 25 and 8% yields. Studies with other dipolarophiles (27) such as norbomene and methyloxazoline generated cycloadducts 94 and 95, respectively, in low overall yield. 

Another important use of BC13 is as a Friedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cydophosphazenes to polymers (81,82) polymerization of olefins such as ethylene (75,83—88) graft polymerization of vinyl chloride and isobutylene (89) stereospecific polymerization of propylene (90) copolymerization of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerization of norbomene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

If the living ROMP of norbomene is terminated with a 9-fold excess of terephthalaldehyde, the chains formed carry an aldehyde end-group which, when activated by ZnCl2, can be used to initiate the aldol-group-transfer polymerization of tert-butyldimethylsilyl vinyl ether621. 

Another example of transient formation of a palladacycle is the Pd-mediated ortho-alkylation and ipso-vinylation of aryl iodides depicted in Scheme 8.23. In this multicomponent reaction the ability of norbomene to undergo reversible arylation and palladacycle formation is exploited. This reaction also illustrates that aryl halides undergo oxidative addition to Pd faster than do alkyl halides, and that aryl-alkyl bond-formation by reductive elimination also proceeds faster than alkyl-alkyl bond-formation. The large excess of alkyl iodide used in these reactions prevents the formation of biaryls. Benzocyclobutenes can also be formed in this reaction, in particular when the alkyl group on the aryl iodide is sterically demanding or when a secondary alkyl iodide is used [161]. 

Olefinic dipolarophiles, such as dimethyl fumarate, fumaronitrile, ethyl vinyl ether, AT-phenylmaleimide, norbomene, and norbomadiene, react with... 

Norbomene adds to photolytically produced ethoxycarbonylnitrene specifically at the exo face the same aziridine is produced in the thermal addition of ethoxycarbonyl azide, but via the triazoline rather than the nitrene, with much imine by-product. There can be problems of selectivity and rearrangements when one reacts ethoxycarbonylnitrene with more complex substrates, e.g. alkenic steroids. Ethoxycarbonylnitrene via a-elimination) adds to vinyl chlorides to give 2-chloroaziridines, which can be rearranged thermally to yield 2-chloroallyl carbamates. This nitrene also adds to enamines, giving an array of rearranged products. A modem discussion of the reactivities of ethoxycarbonylnitrene (electrophilic) in comparison with phthalimidonitrene (nucleophilic) towards alkenes of different electronic properties has tqipeared. ... 

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