Concerted nucleophilic aromatic substitution (CSNAr) has emerged as a powerful mechanistic manifold, in which nucleophilic aromatic substitution can proceed in one step without the need to form a Meisenheimer intermediate. However, all of the CSNAr reactions reported thus far require a stoichiometric strong base or activating reagent, and no catalytic variants have yet been reported. Herein, we report an N‐heterocyclic carbene (NHC)‐catalyzed intramolecular cyclization of acrylamides that contain a 2‐fluorophenyl group on the nitrogen through a CSNAr reaction. By using this catalytic method, it is possible to synthesize an array of quinolin‐2‐one derivatives, which are common structural motifs in pharmaceuticals and organic materials. DFT calculations unambiguously revealed that this reaction proceeds through the concerted nucleophilic aromatic substitution of aryl fluorides, in which a stereoelectronic σ (Cipso‐Cβ)→ σ*(Cipso‐F) interaction critically contributes to the stabilization of the transition state for the cyclization.

We report on the N-heterocyclic carbene (NHC)-catalyzed Truce–Smiles rearrangement of aniline derivatives, in which an unactivated C­(aryl)–N bond is cleaved, leading to the formation of a new C­(aryl)–C bond. The key to the success of this reaction is the utilization of a highly nucleophilic NHC, which enables the formation of a highly nucleophilic ylide intermediate that is generated from an α,β-unsaturated amide.

Single–carbon atom transfer reactions are lacking in organic synthesis, partly because of the absence of atomic carbon sources under standard solution-phase conditions. We report here that N-heterocyclic carbenes can serve as atomic carbon donors through the loss of a 1,2-diimine moiety. This strategy is applicable to single–carbon atom transfer to α,β-unsaturated amides, which can be converted into homologated γ-lactams through the formation of four single bonds to one carbon center in one operation.

We report here that the reactivity order of the leaving group is F > Cl ≥ Br > I in N-heterocyclic carbene-catalyzed CSNAr reactions of aryl halides bearing an α,β-unsaturated amide. Based on a qualitative Marcus analysis, the nature of the transition state in this catalytic CSNAr is primarily determined by the potential energy of the Meisenheimer complex, even though it is not involved as a discrete intermediate in the reaction pathway.

Concerted nucleophilic aromatic substitution (CS N Ar) has emerged as ap owerful mechanistic manifold, in which nucleophilic aromatic substitution can proceed in one step without the need to form aM eisenheimer intermediate. However,a ll of the CS N Ar reactions reported thus far require as toichiometric strong base or activating reagent, and no catalytic variants have yet been reported. Herein, we report an N-heterocyclic carbene (NHC)-catalyzed intramolecular cyclization of acrylamides that contain a2-fluorophenyl group on the nitrogen through aCS N Ar reaction. By using this catalytic method, it is possible to synthesizeanarrayofquinolin-2-one derivatives,w hich are common structural motifs in pharmaceuticals and organic materials.D FT calculations unambiguously revealed that this reaction proceeds through the concerted nucleophilic aromatic substitution of aryl fluorides,i n which as tereoelectronic s (C ipso -C b )! s*(C ipso -F) interaction critically contributes to the stabilization of the transition state for the cyclization. Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.1002/anie.201907837. Scheme 1. S N Ar and CS N Ar reactions. Angewandte Chemie Zuschriften Scheme 3. DFT calculations. a) Energy diagram for the cyclization reaction of 1a with L6.b )HOMO orbitals in TS and the NICS(0) values of Int 1 and TS.c)Charge distribution in TS based on NBO analysis. d) s (C ipso ÀC b )b onding orbital from NBO analysis. e) s*( C ipso ÀF) antibonding orbital from NBO analysis. f) Comparison of the nucleophilicity of the simplified ylide intermediate Int3 with different NHC catalysts based on the HOMO energy levels.