Organocopper reagents cross-coupling reactions

Only perfluoro-tert-butyl copper has been prepared by this method. The compound was isolated in 72% yield from the reaction of m-(tri-fluoromethyl)phenylcopper with perfluoro-fert-butyl bromide in ether-dioxane at 0°C(34). Exchange and cross-coupling reactions occur simultaneously in many reactions between organocopper reagents and various organic halides (69, 97, 174, 217, 220, 266, 297). However, the method is only of limited use as the new reagent [R Cu in Eq. (16)] and its precursor are capable of reacting with both species of halide, RX and R X, present in the mixture. 

S. Valverde, M. Bemabe, A. M. Gomez, and P. Puebla, Cross coupling reactions of 2-(allyloxy-(thio))benzothiazoles with organocopper reagents in dihydropyranoid systems—mechanistic implications of the substrate and the reagent—regiocontrolled and stereocontrolled access to branched-chain sugars, J. Org. Chem. 57 4546 (1992). 

We have found that alkynylsilanes are smoothly converted into alkynylcopper compounds by treatment with CuCl in l,3-dimethyl-2-imidazohdinone (DMI) the copper reagents can be isolated in good yields [563]. This study was the first example of preparation and isolation of organocopper compounds by use of organosilicon reagents. The Si-Cu transmetalation is applicable to the synthesis of alkynyl ketones by Cu-catalyzed alkynylation of acid chlorides (Scheme 10.217). We have also shown that a Cu-mediated system is effective in the cross-coupling reaction between arylsilanes or heteroarylsilanes and aryl hahdes [564]. 

Table 5.4 Cross-coupling reactions of thienyl-based organocopper reagents with acid chlorides.

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