5-Norbomene-2-nitrile

Polymers of Norbornenenitriles. On the basis of preliminary evaluation of the properties of various polynorbornenes, the monomer availability and the polymerization behavior, the polymers of the nitrile derivatives were considered most promising as new materials. The homopolymers of 5-norbomene-2-nitrile and 2-methyl-5-norbornene-2-nitrile and a block copolsnner of 5-nor-bornene-2-nitrile with SBR were prepared and evaluated with respect to their physical properties. The ternary system, WCls-paraldehyde-Al(isoBu)3 was used as the catalyst, which efficiently induced the polymerization at a catalyst-to-monomer ratio as low as ca. 4 x lO . ... 

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 1,3-dipolar cycloaddition reactions of nitrile oxides to unsymmetrically substituted norbomenes (243) and to dicyclopentadiene and its derivatives (244) proceed with complete stereoselectivity. The approach of the dipole takes place exclusively from the exo-face of the bicycloheptane moiety, generally... 

Carboxylic esters of norbomene can be polymerized with Pd-(Il)-nitrile catalysts Pd(RCN)4 x (BF4)2 with R = CH3,C2H5 (39). However, the polymerization takes place only selectively, as mostly the exo isomer polymerizes. 

J.P. Mathew, A. Reinmuth, J. Melia, N. Swords, and W. Risse, (ry-3-allyl) palladium (ii) and palladium (ii) nitrile catalysts for the addition polymerization of norbomene derivatives with functional groups, Macromolecules, 29(8) 2755-2763,1996. 

With DIOP-Pd(0) or -Ni(0) complexes as catalysts, moderate optical yields of up to 35% have been observed (126). Norbomene is convertible to the exo nitrile with up to 40% ee when a BINAP-Pd(0) complex is used (Scheme 57) (127). Ni(0) complexes of sugar-derived 1,2-diol phosphinites catalyze highly selective asymmetric addition of hydrogen cyanide to vinylarenes (128). This method gives the 2-naphthalene-2-propionitrile precursors of nonsteroid anti-inflammatory agents in up to 85% ee and in high yield. 

In a manner analogous to classic nitrile unmes, the additions of tnfluoro-methylacetomtnle phenylimine occur regiospecifically with activated terminal alkenes but less selectively with alkynes [39], The nitrile inline reacts with both dimethyl fumarate and dimethyl maleate in moderate yields to give exclusively the trans product, presumably via epimenzation of the labile H at position 4 [40] (equation 42) The nitrile imine exhibits exo selectivities in its reactions with norbomene and norbornadiene, which are similar to those seen for the nitrile oxide [37], and even greater reactivity with enolates than that of the nitrile oxide [38, 41]. Reactions of trifluoroacetomtrile phenyl imine with isocyanates, isothiocyanates, and carbodiimides are also reported [42]... 

In asymmetric hydrocyanation reactions the desired isomers are the chiral branched products only. Good regioselectivity toward the branched product (>98%) is limited to vinylarenes. Hydrocyanation of 1,3-dienes gives a variety of mixtures depending on the catalyst and conditions 1-alkenes give the linear nitrile as major product [34]. Both are seen in the adiponitrile process in which the unwanted branched 2M3BN (hydrocyanation product from 1,3-butadiene) is isomerized to the linear product 3-pentenenitrile, which is then hydrocyanated by in-situ isomerization to 4-pentenenitrile, resulting in the linear adiponitrile. Thus vinylarenes and cyclic alkenes (mainly norbomene) are usually the substrates of choice for the asymmetric hydrocyanation. Hopefully 1,3-dienes will become feasible substrates in the near future. 

A number of olefins are converted in the presence of tetrakis(tri-o-tolyl phos-phite)nickel(O) into the corresponding nitriles. These additions yield the terminal nitriles predominantly [15]. Systematic investigations were performed on the hydrocyanation of olefins containing the norbomene skeleton 9 as a basic structure. Table 1 demonstrates the development of catalysts to gain stereocontrol of product formation. 

Twieg and coworkers, reported preparation of poly(norbomene) copolymers functionalized with nonlinear optical chromophore side groups. Use was made of (ri -toluene)Ni(C6F5)2, catalyst in the polymerization of norbomene. The nickel complex used to polymerize the norbomene monomers is tolerant to many functional groups found in nonlinear optical chromophores. On the other hand, nitriles and amines other than trisubstituted amines strongly inhibit the reaction. A copolymer of hexylnorbomene and a norbomene-functionalized Disperse Red I chromophore was scaled up and studied in detail. Initial studies indicate that electric field poling is effective but that relaxation of polar order in the poly(norbomene) is faster than in a comparable methacrylate copolymer. The copolymer can be illustrated as follows ... 

The enantioselective hydrocyanation of alkenes has the potential to serve as an efficient method to generate optically active nitriles, as well as amides, esters, and amines after functional group interconversions of the nitrile group. As in asymmetric hydroformylation, asymmetric hydrocyanation requires control of both regiochemistry and stereochemistry because simple olefins tend to generate achiral terminal nitrile products. The hydrocyanation of norbomene will give a single constitutional isomer and was studied initially. However, modest enantioselectivities were obtained, and the synthetic value is limited. ... 

Dipolar Cycloadditions with Nitrile Oxides (Nitrile Oxide—Norbomene Click Chemistry)... 

Figure 1. H-NMR spectra of the polymers obtained from nitrile-, ester-, and amide-subslituted norbomene derioatioes measured in CDCU at room temperature...

The polymerization and the reaction with acyclic unsaturated compounds are considered to take place on the coordination sites of the active catalyst species. Therefore, the effect of various compounds described above reflect, at least in part, their relative ability of coordination to the active species. The effect of acetylenes and allenes as well as that of a,6-un-saturated esters and nitriles may reasonably be explained by their stronger power of coordination in com comparison with that of the norbomene double bond. 

TABLE VI summarizes the physical properties of the polymers. The values of the acrylonitrile-butadi-ene-styrene(ABS) resin and of polycarbonate are included for the sake of comparison. The norbomene polymers have good tensile and flexual properties comparable to those of the ABS resin. The heat distortion temperature (HDT) of poly(5-norbornene-2-nitrile) is raised by... 

Gutsmiedl, K., Wirges, C.T., Ehmke, V., and Carell, T. (2009) Copper-free click modification of DNA via nitrile oxide-norbomene 1,3-dipolar cycloaddition. Organic Letters, 11,2405. 

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