Degradation of natural rubber via cross-metathesis with electron-deficient enes

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Due to the high degree of substitution at its double bond, cross-metathesis of natural rubber (cis-1,4-polyisoprene, NR) with other enes is known to be a challenging task as the accessibility of the double bond is limited and self-metathesis of the other reaction partner prevails [1]. Cross metathesis of NR has been accomplished with several substrates [2] among them acrylates. In this case the degradation lead to semi-telechelic oligomers bearing an electron deficient enoate end group, which has been exploited for further functionalization [3] (see Figure below). However, cross metathesis with acrylates suffers from an additional deactivation pathway of the intermediate methylidene species by deprotonation by a strong base formed in the phospha-Michael addition of dissociated phosphine ligands with acrylates [4]. Consequently typically phosphine free catalysts are used for this and similar transformations.
Herein we present a screening of different catalysts and electron-deficient cross-metathesis partners for the degradation of NR and NR-waste. Emphasis is laid on testing cross-metathesis partners not producing a methylidene species in the catalytic cycle and finding conditions for allowing a further reduction of catalyst loadings for this reaction.
[1] A. K. Chatterjee, T.-L. Choi, D. P. Sanders, R. H. Grubbs, J. Am. Chem. Soc., 2003, 125, 11360-11370.
[2] S. Leimgruber, G. Trimmel, Monatsh. Chem., 2015, 146, 1081-1097.
[3] M. Abbas, M. Neubauer, C. Slugovc, Polym. Chem., 2018, 9, 1763-1766.
[4] G. A. Bailey, D. E. Fogg, J. Am. Chem. Soc., 2015, 137, 7318-7321.
Original languageEnglish
Publication statusPublished - 30 Jun 2019
Event23rd International Symposium on Olefin Metathesis and Related Chemistry - CASA CONVALESCÈNCIA Sant Antoni Mª Claret, 171, Barcelona, Spain
Duration: 30 Jun 20193 Jul 2019


Conference23rd International Symposium on Olefin Metathesis and Related Chemistry
Abbreviated titleISOM 23
Internet address

Fields of Expertise

  • Advanced Materials Science

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