Oxanorbornenes: promising new single addition monomers for the metathesis polymerization. Issue 19 (16th April 2021)

• Record Type: Journal Article
• Authors: Pal, Subhajit; Alizadeh, Mahshid; Kong, Phally; Kilbinger, Andreas F. M.
• Is Part Of: Chemical science. Volume 12:Issue 19(2021)
• Page Start: 6705
• Page End: 6711
• Publication Date: 2021-04-16
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1sc00036e
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Bridgehead revisited: endo -7-oxa norborneneimide derivatives (green) initiate faster but propagate more slowly than the analogous exo -derivatives (red) in ring-opening metathesis allowing the synthesis of alternating and end functional polymers. 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 higher reactivity towards ring-opening metathesis with Grubbs' 3rd generation catalyst (G3 ) than the corresponding exo -isomers. A very high selectivity for the reaction of G3 with endo over the exo -isomers could be shown. Furthermore, single molecular addition of the endo -isomers with G3 was observed. On the other hand, pure exo -monomers could successfully be homopolymerized. Mixtures of exo - and endo - monomers, however, prevented the homopolymerization of the exo -monomer. Such mixtures could successfully be copolymerized with cycloalkenes, resulting in alternating copolymers. An oxanorbornadiene derivative could be shown to undergo single addition reactions, exploited in the preparation of mono-end functional ROMP polymers. These could be selectively derivatized via endgroup selective thiol-ene click reactions. A thiol and alcohol end functional ROMP polymer was synthesized, and the efficient end functionalization was confirmed by 1 H NMR spectroscopy and MALDI-ToF spectrometry.