| Summary: | Two approaches for the preparation of some novel functionalised polymers were investigated using a combination of nitrile oxide chemistry and Ring opening Metathesis Polymerisation (ROMP). In the first case, homopolymers of norbornene (NBE) and norbornadiene (NBD) were synthesised and then modified by 1,3-dipolar cycloaddition to nitrile oxides (RCNO) to the poly(di)enes. These reactions were studied at varying molar ratios of the various nitrile oxides (R = Ph, CO<sub>2</sub>Et, CO<sub>2</sub>Me), which were generated <i>in situ</i> by the thermal dehydrochlorination of the corresponding hydroximoyl chlorides. The second method was via the ROMP of novel isoxazolino norbornenes. Thus, <i>exo</i>-3-phenyl-4,7-methano-3a,4,7,7a-tetrahydrobenzisoxazole and <i>exo</i>-3-oxa-4-aza-ethyl-tricyclo[5.2.1]dec-4-ene-5-carboxylate, were synthesised via the cycloaddition to NBD of the corresponding nitrile oxides, and were subsequently polymerised using {RuCl<sub>2</sub>(=CHPh)[P<sub>6</sub>H<sub>11</sub>)<sub>3</sub>]<sub>2</sub>] 1 and {RuCl<sub>2</sub>(=CHPh)[P(C<sub>6</sub>H<sub>11</sub>)<sub>3</sub>][IH<sub>2</sub>Mes]} 2. Extensive use has been made of monomeric alkenes as model compounds both to test the synthetic pathways and to assist in establishing the structure of products from the equivalent polymer reactions, for this purpose <i>trans</i>-5-decene and cyclopentene were used. The Isoxazolino norbornenes were polymerised with control of molecular weight (M<sub>w</sub> and M<sub>n</sub>) by reacting <i>exo</i>-3-oxa-4-aza-ethyl-tricyclo[5.2.1]dec-4-ene-5-carboxylic with varying ratios of hex-1-ene as a chain transfer agent (CTA). Thus, [CTA]/[Monomer] of 0.00, 0.5, 0.10, 0.15 and 0.25 yielded oligomers with an average degree of polymerisation av DP, of 554, 157, 16, 8 and 4 (determined by GPC and NMR end group analysis). A sample of an isoxazolino functionalised oligomer (n = 16) was converted into its hydrogenated analogue (83%) by treatment with <i>p</i>-toluenesulfonhydrazide. Having established that isoxazolino-norbornenes were suitable monomers for ROMP, the feasibility of using the analogues isoxazolino compounds was examined. <i>exo-</i>4-Methyl-5<i><sup>exo</sup></i>-phenyl-3-oxa-4-aza-tricyclo[5.2.1.0<sup>2,6<i>oxo</i></sup>]dec-8-ene (70%), was prepared by the cycloaddition of <i>N</i>-methyl-<i>C</i>-phenyl nitrone to NBD. The analogous <i>exo, endo </i>cycloadduct from the cycloaddition of <i>C,N</i>-diphenylnitrone to NBD was also synthesised (32%) and the isoxazolidines polymerised using the initiators 1 and 2. The polymerisation of the <i>N</i>-methyl-<i>C</i>-phenyl and the <i>C-N-</i>diphenyl isoxazolidines with 1 yielded polymers with an av DP of 251 and 234, whereas with 2 the chain length increased to n = 490 and 683 respectively. An increase in polydispersity index (PDI) of 1.84 to 2.37 and 1.54 to 2.09 for was observed on going from 1 to 2.
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