Hans, Andreas C.Becker, Patrick M.Haußmann, JohannaSuhr, SimonWanner, Daniel M.Lederer, VeraWillig, FelixFrey, WolfgangSarkar, BiprajitKästner, JohannesPeters, René2023-08-312023-08-3120231521-37731433-78511860332641http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-ds-134775http://elib.uni-stuttgart.de/handle/11682/13477http://dx.doi.org/10.18419/opus-13458A catalyst type is disclosed allowing for exceptional efficiency in direct 1,4‐additions. The catalyst is a zwitterionic entity, in which acetate binds to CuII, which is formally negatively charged and serving as counterion for benzimidazolium. All 3 functionalities are involved in the catalytic activation. For maleimides productivity was increased by a factor >300 compared to literature (TONs up to 6700). High stereoselectivity and productivity was attained for a broad range of other Michael acceptors as well. The polyfunctional catalyst is accessible in only 4 steps from N‐Ph‐benzimidazole with an overall yield of 96 % and robust during catalysis. This allowed to reuse the same catalyst multiple times with nearly constant efficiency. Mechanistic studies, in particular by DFT, give a detailed picture how the catalyst operates. The benzimidazolium unit stabilizes the coordinated enolate nucleophile and prevents that acetate/acetic acid dissociate from the catalyst.eninfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc/4.0/540article2023-04-19