Mechanical Force Induces Ylide‐Free Cycloaddition of Nonscissible Aziridines

Abstract

The application of aziridines as nonvulnerable mechanophores is reported. Upon exposure to a mechanical force, stereochemically pure nonactivated aziridines incorporated into the backbone of a macromolecule do not undergo cis–trans isomerization, thus suggesting retention of the ring structure under force. Nonetheless, aziridines react with a dipolarophile and seem not to obey conventional reaction pathways that involve C−C or C−N bond cleavage prior to the cycloaddition. Our work demonstrates that a nonvulnerable chemical structure can be a mechanophore.

A guide to direct mechanocatalysis

“…17 Indeed, a plethora of catalytic reactions have already been performed in ball mills. Well-known catalytic reactions such as, C-N and C-C cross coupling, 18,19 cycloaddition, 20 polymer reactions, 21 C-H activation 22 were successfully conducted in the ball-mill, although the question whether they process via comparable reaction mechanism or entirely different remains widely unanswered. Interestingly, some of these reactions that were conducted mechanochemically showed remarkable advantages over the corresponding conventional methods.…”

“…Another interesting example is the highly stereo-selective mechanochemical reaction of aziridine containing polymers with dipolarophiles reported by H. J. Yoon group in 2020. 21 This reaction was shown to not proceed via conventional reaction pathways, thus underscoring the promise of employing mechanochemistry to pioneer new synthetic approaches.…”