Journal ArticleFree carbenes from complementarily paired alkynesXu, Qian; Hoye, Thomas RCarbenes (R1R2C:) [like radicals, arynes, and nitrenes] constitute a significant family of neutral, high-energy, reactive intermediates – fleeting chemical entities that undergo rapid reactions. An alkyne (R3C≡CR4) is a fundamental functional group that houses a high degree of potential energy; however, the substantial kinetic stability of alkynes renders them conveniently handleable as shelf-stable chemical commodities. The ability to generate metal-free carbenes directly from alkynes, fueled by the high potential (that is, thermodynamic) energy of the latter, would constitute a significant advance. We report here that this can be achieved simply by warming a mixture of a 2-alkynyl-iminoheterocycle (a cyclic compound containing a nucleophilic nitrogen atom) with an electrophilic alkyne. We demonstrate considerable generality for the process: many shelf-stable alkyne electrophiles engage many classes of (2-alkynyl)heterocyclic nucleophiles to produce carbene intermediates that immediately undergo many types of transformations to provide facile and practical access to a diverse array of heterocyclic products. Key mechanistic aspects of the reactions are delineated.Springer Nature Limited2024-06-2510518686Nature Chemistry1755-4330https://doi.org/10.1038/s41557-024-01550-92155042National Science Foundation