Oxanorbornenes: promising new single addition monomers for the metathesis polymerization

Abstract

Higher ring-opening metathesis propagation rates of exo-norbornene derivatives over endo derivatives are well established in the literature. Here, we report for the first time that endo-isomers of oxanorbornene derivatives show...

Complex Polymer Architectures Using Ring-Opening Metathesis Polymerization: Synthesis, Applications, and Practical Considerations

“…Substituted norbornenes are used widely in ROMP, specifically 5-substituted or 5,6-substituted, and the factor that influences the propagation rate the most is the endo / exo stereochemistry. It has been known for decades that exo -norbornene monomers polymerize faster than the equivalent endo structures by a factor of 20–100. , This phenomenon has been validated across various catalysts, solvents, and substituents, and it is largely attributed to steric effects and the fact that Lewis basic units such as esters can coordinate to the catalyst in endo monomers. ,− Therefore, exo monomers are used much more widely than endo monomers, despite their substantially higher cost and need for extended synthetic procedures and purifications compared with the cheaper and more widely available endo monomers. , However, endo monomers remain useful in specific scenarios, including as diluent monomers and in cases where gradient structures are targeted …”

Diels–Alder Cycloadditions of Bio-Derived Furans with Maleimides as a Sustainable «Click» Approach towards Molecular, Macromolecular and Hybrid Systems

“…It is important to note that endo end exo oxanorbornenes can exhibit different reactivity in ROMP. For example, exo oxanorbornene, formed from 2-alkyl furans and N-methyl maleimide, underwent efficient homo-polymerization in the presence of G3 catalyst, while the endo isomer could not be polymerized [72].…”

Intermolecular Diels-Alder Cycloadditions of Furfural-Based Chemicals from Renewable Resources: A Focus on the Regio- and Diastereoselectivity in the Reaction with Alkenes

“…The endo- and exo -DA adducts have different steric properties and convert to furan and alkene components at different temperatures, which may be important in the development of various dynamic systems [ 39 , 40 ]. Moreover, the stereo structure of cyclic alkenes may influence the reactivity in ring-opening metathesis polymerization used for the synthesis of stereoregular polymers [ 41 ]. This difference for furan-derived oxanorbornanes was clearly demonstrated by Kilbinger and coworkers.…”

“…They showed in several examples that furan/maleimide DA adducts react quickly and selectively with the G3 catalyst, resulting in the formation of monomolecular carbene complexes that display low reactivity with the second molecule of oxanorbornane (both endo or exo ) due to unfavorable steric factors ( Scheme 2 a). In contrast, exo -oxanorbornane counterparts undergo efficient homopolymerization under the same reaction conditions ( Scheme 2 b) [ 41 ].…”