Characterization of a Silver Vinylcarbene Intermediate in Carbene–Alkyne Metathesis and Its Concerted C(sp2)–H Bond Insertion

Abstract

Herein we present compelling evidence of the intervention of electrophilic silver vinylcarbenes in the carbene-alkyne metathesis (CAM) reaction, leading to a pivotal C(sp2)-H insertion process. The delicate equilibrium between the stability and reactivity of transient species is crucial for efficient detection. Through meticulous mechanistic exploration, we unveil that the mechanism for the C(sp2)-H insertion hinges on the substitution pattern. Indeed, it departs from the previously documented stepwise mechanism (involving Wheland intermediates), and it follows a concerted route, quite uncommon for this transformation

The authors are grateful for finantial support from Projects PID2021-127423NB-I00 to A.P., PID2020-113711GB-I00 and PID2023-146849NB-I00 to A.P.-Q., PID2019-106699GB-I00 to A.Co., PID2020-113797RB-C21 and PID2023-146946NB-I00 to P.J.P. and A.C. funded by the Ministerio de Ciencia, Innovación y Universidades of Spain MCIU/AEI/10.13039/501100011033 and FEDER, UE,; RED2022-134074-T and RED2022-134331-T for network support, and from the Generalitat de Catalunya (2021-SGR-623 to A.R., 2021SGR-475 to A.Co. projects). We thank the Spanish Ministerio de Universidades for the predoctoral fellowship FPU18/02912 to À.D.-J. and FPU20/00707 to R.M.-C. and the Catalan Government for the predoctoral fellowship 2022 FI_B 00605 to A.A.-N. and a Beatriu de Pinós-AGAUR Postdoctoral grant (2022BP00051) to A.S.. A.P.-Q., A. Co, and A.P. are Serra Húnter Fellows and A.P. and A.Co. thank ICREA Academia Prizes

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