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The Role of Added Acids in C–H Functionalizations by Palladium Carboxylates

Authors: Váňa Jiří | Bartáček Jan | Hanusek Jiří | Roithová Jana | Sedlák Miloš

Year: 2019

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	The Role of Added Acids in C–H Functionalizations by Palladium Carboxylates	Finding optimal reaction conditions of palladium catalyzed C–H functionalization reactions controlled by directing groups (DG) is usually complex and requires individual approach to each reaction. Knowledge of the reaction mechanism and effects of reaction components can rationalize the screening process and thus save human, financial and environmental resources. Our work examines effects of added carboxylic acids in the reaction system. These may in principle influence reaction by at least five different ways (Figure 1a): form a precatalyst from palladium acetate; [1] protonate substrate; affect the reactivity of palladium in the C–H activation step; affect oxidation potentials of palladacycles or exchange anions in other common reagents; e.g. PhI(OAc)2, Cu(OAc)2, AgOAc. We have shown that the key factor for optimizing reaction conditions is to find a balance between two opposing effects of the carboxylic acid in the reaction mixture; generation of more reactive palladium catalyst vs. deactivation of substrate by its protonation.[2] This simple principle is illustrated by examples of stoichiometric C-H activations as well as catalytic C-H functionalizations. Furthermore, it offers workflow for selection of suitable added acids (Figure 1b).	Palladium catalyst; carboxylic acids; palladium acetate; carboxylates