2-Methylene-5-norbornene

Since this reaction is a unimolecular example of the selective hydrogenation of an alkene mixture, the successful saturation of the less-substituted double bond should take place most readily over those catalysts that are most effective for the preferential saturation of one olefin in a mixture. Ruthenium has not been used extensively for such hydrogenations, but P-2 Ni(B) has been effective in promoting the selective hydrogenation of one of the double bonds in 46, methylene norbornene (49) (Eqn. 15.30), dicyclopentadiene (50) (Eqn. 15.31), and 2-methyl-1,5-hexadiene (51) (Eqn. 15.32).6 9,80,81... 

Infra-red analysis may be used to estimate dicyclopentadiene, trans-hexadiene, ethylidene norbornene and methylene norbornene although calibration is indicated. Other methods used include pyrolysis, gas chromatography, density measurement and refractive index measurement. 

Where the diene provides terminal unsaturation, radical addition at the double bond may occur successively in a chain reaction akin to polymerization so that one peroxide radical could produce many cross-links, i.e. to give a cross-linking efficiency greater than 1. Such results have been observed with EPDM rubbers based on methylene norbornene and on vinyl norbornene. 

A carbazole-functionalized norbornene derivative, 5-CN-carbazoyl methy-lene)-2-norbornene, CbzNB, was polymerized via ROMP using the ruthenium catalyst Cl2Ru(CHPh)[P(C6Hii)3]2 [100]. The polymerization was conducted in CH2C12 at room temperature, to afford products with polydispersity indices close to 1.3. Subsequent addition of 5-[(trimethylsiloxy)methylene]-2-norbornene showed a clear shift of the SEC trace of the initial polymer, indicating that a diblock copolymer was efficiently prepared in high yield. 

The norbornene derivative 16, obtained exclusively as the exo adduct via a Diels-Alder reaction of itaconic anhydride with cyclopentadiene followed by hydrolysis and esterification [7], was found to be a suitable precursor for an enolate of type 14 (Scheme 2). Due to the quaternary center at C-3 eno-lization with base proceeded unambiguously, giving rise to a diastereomeric mixture of lactones 17/18 after reaction with hexanal. Retro-Diels-Alder reaction led to the monocyclic lactones 19/20 (2 1), elegantly unmasking the cxo-methylene group found in so many paraconic acids [8]. Hydrolysis of this mixture in refluxing butanone with 6 N HCl [9] effected epimerization... 

Two examples of the chain reaction involving the a-methylene radical are the irradiation of acetone in the presence of norbornene,107 and that of cyclohexanone in the presence of cyclohexene.108 106 These reactions predominate so that the other products derived from the photochemical reactions were not initially characterized. 

A successive polarization of the exocyclic double bond, as monitored by the carbon shifts in the 7-methylene derivatives of norbornane, norbornene and norbornadiene (Table 4.12), is attributed to homoconjugative interaction of it bonds, pushing it electrons towards the exo methylene carbon [239]. 

An EPDM rubber is produced by the terpolymerisation of ethylene and propylene with a small amount (typically of the order of 5%) of an unconjugated di-olefin. The di-olefins used, include dicyclopentadiene, 1,4-hexadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene and methyl tetrahydroindene, 1,5 cyclo octadiene. A number of other dienes [74,75] have been tried. Infrared spectroscopy [35] is used to find out the ter monomer content. The characteristic peaks for the ter monomer are shown in Table 3.4. In view of the relatively low concentrations, it is probable that ter monomer base units are present largely as isolated units in EPDM but the distribution of propylene and methylene sequences is of considerable interest. 

The polymerization proceeds without termination or chain transfer to give poly-norbomene with a narrow molecular weight distribution [35], After an induction period, the rate of monomer consumption (rate of polymerization) becomes constant, indicating a zero-order dependence on the monomer concentration. The induction period is caused by part of titanacycle 7 undergoing non-productive, but rapidly reversible, cleavage to norbornene and the titanium methylene complex, Eq. (17 a). 

Boamfa et al. investigated macroscopic orientation of disubstituted cyano-biphenyl poly(norbornene) IV-n (n=3,5) using different magnetic fields of up to 20 T. Both the degree of orientation and optical properties were compared with a cyanobiphenyl-substituted acrylate polymer with a spacer of four methylene units [49,50]. 

Lor polymers in which the mesogen is separated by a spacer of six methylenes units from the polymer backbone, it is obvious that the more rigid poly(norbornene)s favor nematic liquid crystalline phases. Poly-(VI-6) with the rigid and bulky 2,5-dimethine oxacyclopentane-3,4-dicarboximide unit in the main chain does not show liquid crystalline behavior (Table 6, entry 12). The more flexible poly-(II-6) backbone allowed the formation of a nematic mesophase. If the mesogen density was increased, as realized in poly-(IV-6), the isotropization temperature was found to be 26 °C higher than that for poly-... 

For a spacer length of 11 methylene units, all polymers showed smectic mesophases except for poly-(II-ll) and poly-(VII). Even the flexible poly-(cy-clooctene) main chain prevented a smectic mesophase. Compared to all of the other polymer architectures, poly-(II-ll) and poly-VII present the lowest ratios of mesogens to atoms in the main chain. It can therefore be assumed that smectic phases will only be formed when there is sufficient mesogen density. For the norbornene chain, it is notable that a high Z/E-ratio and a high tactic-ity increased the stability of the smectic A phase. 

The introduction of perfluorinated groups generally favors microphase separation due to the immiscibility of fluorocarbons with hydrocarbons [66]. Norbornene derivatives with perfluorinated endgroups in the side chain were prepared by Wewerka et al. [67]. Monomer XII contained a relatively long (CF2)8-chain, separated via a long spacer (11 methylene-groups) from the norbornene, whereas monomer XIII has two relatively short (CH2)2(CF2)4-side chains (Fig. 11). Homopolymers and block copolymers were synthesized with one fluorinated monomer (XII or XIII) and one non-fluorinated non-liquid crystalline monomer (NBDE or COEN) with the Schrock-type initiators 4 and 5, respectively, leading to microphase-separated block copolymers. Table 9 and Table 10 summarize the physico-chemical properties of the homopolymers and block copolymers. 

Homoconjugative addition. Benzenesulfenyl chloride adds to 5-methylene-2-norbornene (1) to give 1 -chloromethyl-3-nortricyclyl phenyl sulfide (2) in good yield. ... 

SYNS BENZOEPIN BEOSIT BIO 5,462 CHLORTHIEPIN CRISULFAN CYCLODAN DEVISULPHAN ENDOCEL ENDOSOL ENDOSULPHAN ENSURE ENT 23,979 FMC 5462 l,2,3,4,7,7-HEXACHLOROBICYCLO(2.2.1)HEPTEN-5,6-BIOXYMETHYLENESULFITE a,P-l,2,3,4,7,7-HEXA-CHLOROBICYCLO(2.2.1)-2-HEPTENE-5,6-BISOXY-METHYLENE SULFITE HEXACHLOROHEXA-HYDROMETHANO-2,4,3-BENZODIOXATHIEPIN-3-OXIDE 6,7,8,9,10,10-HEXACHLORO-l,5,5a,6,9,9a-HEXAHYDRO-6,9-METHANO-2,4,3-BENZODIOXA-THIEPIN-3-OXIDE 1,4,5,6,7,7-HEXACHLORO-5-NORBORNENE-2,3-DIMETHANOL CYCLIC SULFITE ... 

VII) 5-(2, 4, 4 -trimethyl-l, 3 -butadienyl)-2-norbornene, associated with 50% of 5-(2 -methylene-4 -methyl-3 -pentenyl)-2-norbornene... 

Curing formulation Polymer =100 HAF Carbon Black = 50 Naphthenic Oil = 5 ZnO = 5 S = 2 TMTD = 1 MBT = 0.5 Temp. = 145 °C. S. Table 1 ENB = 5-ethylidene-2-norbornene 1,4-HD = 1,4-hexadiene DCP = dicyclopentadiene MNB = 5-methylene-2-norbomene. Cross-linking reaction rate constant. 

Intramolecular alkylation of the sulfur atom of thietanes also is invoked in reactions of a-haloalkylthietanes, for example, the formation of 75 in reactions of alcohol 74. The salt 75 has been isolated. The ion 76 is attacked at carbon by acetate ion, but at sulfur by hydride ion. The reactions of sulfur dichloride with 5-exo-methylene-2-norbornene to give 53 is believed to involve an intramolecularly S-alkylated thietane. ... 

A similar approach to enantiomericaUy pure norbornene derivatives was developed by Nouguier et al. who employed l,3 2,4-di-0-methylene acetals of pentitols as chiral templates [62]. Hence, the 5-(5-acryloyl-D-arabinatol derivative 82 underwent highly stereoselective Lewis acid catalyzed cycloaddition with cyclopentadiene, giving 83 (Scheme 10.28). The stereochemical outcome of the reaction was explained in terms of the chelate complex 84, in which the chair-like dioxane ring and the acrylic moiety are fixed in two parallel planes, forcing the diene to approach the cisoid acrylate from the ii-face. The synthesis and utihty of various methylene protected glycosides have also been reported by this group [63-66]. 

The anisotropy of double bonds is more difficult to assess, because they have three nonequivalent axes. Thus, the McConnell equation, with only two axes, does not apply. Protons situated over double bonds are, in general, more shielded than those in the plane (Figure 3-8), both for alkenes (Figure 3-8a) and for carbonyl groups (Figure 3-8b). The position of the methylene protons in norbornene (3-8) may be explained in this fashion. 

In a later paper Meinwald concluded that nitrosyl chloride adds cis to strained double bonds, such as that in norbornene, but that it adds trans to unstrained olefins (A -octalin). In accordance with this view of the addition is a report by Hassner on the reaction of cholesteryl acetate (4). Nitrosyl chloride was passed into methylene chloride or carbon tetrachloride until a deep burgundy color developed, the steroid... 

Oxatrimethylenemethanepalladium complexes can also be generated by oxidative addition of palladium(O) to 5-methylene-l,3-dioxolan-2-ones and subsequent decarboxylation. Again, reaction with norbornene, norbornadiene and dicyclopentadiene yields polycyclic cyclopropyl ketones in medium to high yield (Table 19). In this case, tetrakis(triphenylphosphane)pal-ladium(O) was the best catalyst found, whereas tris(dibenzylideneacetone)palladium(0)-chloro-form/triphenylphosphane (see above) and bis(cycloocta-l,5-diene)nickel/triphenylphosphane (used in stoichiometric amounts) proved less efficient. 

Table 19. Cyclopropanation of Norbornene and Related Systems with 5-Methylene-l,3-dioxolan-2-ones Catalyzed by Palladium(O) ...

In an analogous manner, an azatrimethylenemethanepalladium complex can be generated from 4-methylene-3-tosyloxazolidin-2-one the intermediate reacts with two equivalents of norbornene and related systems to give polycyclic cyclopropyl-A -tosyl imines 6-8. ... 

The following reactions of norbornene and other nonfunctionalized alkenes with substituted methylenecyclopropanes illustrate these points. (1-Methylethylidene)- and (diphenyl-methylene)cyclopropane (1 R = Me, Ph) give rise to the same type of cycloadducts in the presence of either nickel(O) or palladium(O) catalysts. Even at temperatures as low as 40 "C with bis(> -cycloocta-l,5-diene)nickel(0) as catalyst, 2 may be isolated in 70% yield. The reaction can be extended to vinylbenzene and ethene at temperatures of between 40 and 60 °C, where it may be advantageous to use (cyclododeca-l,3,5-triene)nickel(0) ° as a source of the catalytically active nickel(O) species instead of bis(j7" -cycloocta-l,5-diene)nickel(0). ° This is because ligand dissociation from the former complex is more facile, especially at relatively low temperatures. 

Benzylidenetricyclo[5.2.1.0 ]decane (5) is the major poduct from the [3 + 2] cycloaddition of either benzylidenecyclopropane (3) or l-methylene-2-phenylcyclopropane (4) and norbornene in both nickel(O)- and palladium(0)-catalyzed reactions. Ring-substituted products, anti- and 5yn-4-methylene-3-phenyltricyclo[5.2.1.0 ]decane (6A) and (6B), respectively, are formed in minor amounts. Whereas under the influence of the palladium(O) catalyst the reaction requires 70-120 °C to proceed at a reasonable rate, nickel(O) as a more active catalyst induces the reaction readily at 40 °C. Combined yields are, at least with the palladium(O) catalysts, close to 100% in all cases. 

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