Stereospecific polymerization of donor-acceptor cyclopropanes with C(sp3)-H bonds as the dormant species

doi:10.1039/d6py00314a

Stereospecific polymerization of donor-acceptor cyclopropanes with C(sp3)-H bonds as the dormant species

2026-05-01

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DOI：10.1039/d6py00314a

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Abstract

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Chiral polymers have long attracted interest in polymer chemistry; however, accessing those with unique C3 repeating units remains a significant challenge. Here, we report a stereospecific ring-opening polymerization (ROP) of enantiopure donor-acceptor cyclopropanes (DACs), enabled by MgBr2/DBU cooperative catalysis and a C-H bond-mediated reversible-deactivation equilibrium, yielding a range of chiral homopolymers and stereo-block copolymers. Stoichiometric reactions of distinct DACs revealed an unprecedented structure-stereospecificity relationship. DFT calculations provide mechanistic insights, indicating that a phenyl substituent on the cyclopropane favors a stereoinvertive S(N)2 pathway, whereas a vinyl group largely stabilizes the alpha-carbocation, thus promoting a mixed S(N)1/S(N)2 mechanism that leads to atactic polymer formation.

Keywords:

RING-OPENING POLYMERIZATION

CATALYST

SELECTIVITY

POLYETHERS

SYSTEM

Stereospecific polymerization of donor-acceptor cyclopropanes with C(sp3)-H bonds as the dormant species

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