Issue 42, 2019

Resonance promoted ring-opening metathesis polymerization of twisted amides


The living ring-opening metathesis polymerization (ROMP) of an unsaturated twisted amide using the third-generation Grubbs initiator is described. Unlike prior examples of ROMP monomers that rely on angular or steric strain for propagation, this system is driven by resonance destabilization of the amide that arises from geometric constraints of the bicyclic framework. Upon ring-opening, the amide can rotate and rehybridize to give a stabilized and planar conjugated system that promotes living propagation. The absence of other strain elements in the twisted amide is supported by the inability of a carbon analogue of the monomer to polymerize and computational studies that find resonance destabilization accounts for 11.3 kcal mol−1 of the overall 12.0 kcal mol−1 ring strain. The twisted amide polymerization is capable of preparing high molecular weight polymers rapidly at room temperature, and post-polymerization modification combined with 2D NMR spectroscopy confirms a regioirregular polymer microstructure.

Graphical abstract: Resonance promoted ring-opening metathesis polymerization of twisted amides

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Article information

Article type
Edge Article
20 Jul 2019
30 Aug 2019
First published
30 Aug 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2019,10, 9729-9734

Resonance promoted ring-opening metathesis polymerization of twisted amides

M. Xu, K. K. Bullard, A. M. Nicely and W. R. Gutekunst, Chem. Sci., 2019, 10, 9729 DOI: 10.1039/C9SC03602D

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