Copper-catalyzed allylic substitution mechanism

Although many aspects of this mechanism have been accepted, computational studies by Nakamura and experimental studies by Bertz and Ogle suggest that modifications to this proposal are needed to fit the current data. Bertz and O e obtained the first spectroscopic data on the allylcopper(III) intermediates fiiat are commonly proposed in copper-catalyzed allylic substitution reactions. Their data imply that the structure of the aUyl dimethylcopper(ni) species contains a ir-allyl unit. 

In addition to benzylations, palladium-catalyzed C-H allylation reactions have also been described, but they usually involve the electrophilic substitution of an electron-rich (hetero)arene with a 7t-allyl palladium complex and therefore deviate from the scope of this chapter [41, 42]. In contrast, the palladium/copper-catalyzed allylation of polyfluoroarenes with allyl carbonates (Scheme 19.27) has been reported to occur through a different mechanism [43]. Thus, base-induced cupration of the arene would give rise to intermediate 15 that was previously characterized by X-ray crystallography [44]. Attack of the in sitw-generated JT-allyl... 

Related to the copper-catalyzed Michael addition reaction, allyl phosphates furnish substitution products via the anti Sn2 mechanism when treated with an appropriate Grignard reagent in the presence of catalytic amount of CuCN and 1 equiv of TMSCI (eq 43). ... 

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