A Retro-Staudinger Cycloaddition: Mechanochemical Cycloelimination of a β-Lactam Mechanophore
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 ^1H 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.
Additional Information© 2015 American Chemical Society, Received: July 14, 2015. Published: August 21, 2015. This work was supported in part by the National Science Foundation (CHE 1300313). M.J.R. gratefully acknowledges the Arnold and Mabel Beckman Foundation for a Beckman Institute Postdoctoral Fellowship. The authors declare no competing financial interest.
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