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Room-Temperature, Ligand- and Base-Free Heck Reactions of Aryl Diazonium Salts at Low Palladium Loading: Sustainable Preparation of Substituted Stilbene Derivatives
Ist Teil von
Chemistry : a European journal, 2010-05, Vol.16 (17), p.5191-5204
Ort / Verlag
Weinheim: WILEY-VCH Verlag
Erscheinungsjahr
2010
Link zum Volltext
Quelle
Wiley Online Library
Beschreibungen/Notizen
The Pd(OAc)2‐catalyzed Heck reaction of aryl diazonium salts with 2‐arylacrylates led to cis‐stilbenes with good to excellent stereoselectivity. The environmentally friendly protocol developed in this work features low palladium loading in technical‐grade methanol at room temperature under base‐, additive‐, and ligand‐free conditions. The same protocol applied to simple Heck coupling of aryl diazonium salts with methyl acrylate allows astonishingly low palladium loading, down to 0.005 mol %. The stereoselectivity experimentally observed for the synthesis of cis‐stilbenes has been rationalized by DFT calculations. Moreover, the role of methanol in promoting the reaction has been clarified by a computational study.
Simplicity does not mean inefficiency! The Pd(OAc)2‐catalyzed Heck reaction of aryl diazonium salts with 2‐arylacrylates led to cis‐stilbenes with good to excellent stereoselectivity. This sustainable protocol features low palladium loading in methanol at room temperature under ligand‐ and base‐free conditions. The stereoselectivity experimentally observed for the synthesis of cis‐stilbenes has been rationalized by DFT calculations.