A Retro-Staudinger Cycloaddition: Mechanochemical Cycloelimination of a β-Lactam Mechanophore
Maxwell J Robb1, Jeffrey S Moore1
1Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
Abstract:
Mechanical activation of a β-lactam mechanophore using ultrasound induces a formal [2 + 2] cycloelimination reaction producing ketene and imine functional groups--the reverse reaction of the Staudinger cycloaddition. This transformation is predicted by computational modeling and verified by kinetics and UV-vis absorption measurements as well as polymer end-group analysis using (1)H and (13)C NMR spectroscopy. Addition of the β-lactam motif to the current repertoire of covalent mechanophores coupled with the diverse reactivity of the ketene functional group provides a promising new platform for achieving materials capable of autonomic self-healing behavior in response to external forces.
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