Volume 58, Issue 49 pp. 17771-17776
Research Article

Tuning the Reactivity of Cyclopropenes from Living Ring-Opening Metathesis Polymerization (ROMP) to Single-Addition and Alternating ROMP

Jessica K. Su

Jessica K. Su

Department of Chemistry, Stanford University, Stanford, CA, 94305 USA

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Zexin Jin

Zexin Jin

Department of Chemistry, Stanford University, Stanford, CA, 94305 USA

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Rui Zhang

Rui Zhang

Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260 USA

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Gang Lu

Gang Lu

Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260 USA

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Prof. Dr. Peng Liu

Corresponding Author

Prof. Dr. Peng Liu

Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260 USA

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Prof. Dr. Yan Xia

Corresponding Author

Prof. Dr. Yan Xia

Department of Chemistry, Stanford University, Stanford, CA, 94305 USA

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First published: 30 September 2019
Citations: 29

Graphical Abstract

A simple change in the substituents on cyclopropene rings elicited strikingly different modes of metathesis reactivity, switching from living homopolymerization to either selective single-addition or alternating copolymerization. In both cases well-controlled polymers were obtained.

Abstract

Ring-opening metathesis polymerization (ROMP) has become one of the most important living polymerizations. Cyclopropenes (CPEs) remain underexplored for ROMP. Described here is that the simple swap of 1-methyl to 1-phenyl on 1-(benzoyloxymethyl)CPEs elicited strikingly different modes of reactivity, switching from living polymerization to either selective single-addition or living alternating ROMP. The distinct reactivity stems from differences in steric repulsions at the Ru alkylidene after CPE ring opening. Possible olefin or oxygen chelation from ring-opened CPE substituents was also observed to significantly affect the rate of propagation. These results demonstrate the versatility of CPEs as a new class of monomers for ROMP, provide mechanistic insights for designing new monomers with rare single-addition reactivity, and generate a new functionalizable alternating copolymer scaffold with controlled molecular weight and low dispersity.

Conflict of interest

The authors declare no conflict of interest.

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