Cocatalysis copper

Another version of the Conia-ene reaction is the focus of this research. Here the reaction of y-alkynic (3-ketoesters was tested.48 The screening resulted in a copper / silver cocatalysis system. It remains unclear why the authors did not at least run some reactions with gold catalysts, too, especially since they even cite the work on the gold-catalyzed Conia-ene reaction in the introduction (Section 12.1). 

Cocatalysis with copper salts has proven its efficiency in the enhancement of the reaction rate, particularly in polar solvents. Discovered by Liebeskind and Fengl , and largely exploited, the cocatalytic effect of Cu(I) depends on the reaction conditions in two... 

The potential of palladium-catalyzed aminochlorination reactions of alkenes dates back to their isolation as side products in aminocarbonylation reactions under copper(II)dichloride cocatalysis [47d]. These reactions were later developed further using copper(II) salts as co-oxidants or reoxidants, respectively, and concomitantly as halide sources. For example, Chemler showed that various aminohalogenation reactions proceed under palladium catalysis in the presence of potassium carbonate as base in moderate to excellent yields in the presence of an excess of the copper oxidant [80]. Both five- and six-membered rings 115 and 116 were formed under these conditions from allyl anilines 114 (Scheme 16.28). Among other examples... 

A more efficient system was obtained if copper acetate was replaced by salen-type cobalt complexes as catalysts, operating together with hydroquinone or quinone. Finally, incorporation of a hydroqninone as part of the salen ligand gave an even more efficient catalyst that did not reqnire cocatalysis by quinone (Scheme 11). 

A general procedure for the synthesis of 4-arylpiperidines 64 via the coupling of 4-(A-BOC-piperidyl)zinc iodide, generated from zinc insertion of 63 with improved conditions, with aryl halides and triflates in the presence of palladium/copper cocatalysis has been reported. ... 

Scheme 5.8 Copper cocatalysis in molybdenum and ruthenium aerobic oxidation systems.

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