Corriu-Kumada cross-coupling

Because of the extraordinary strength of the carbon-fluorine bond, transition metal-mediated activation of fluoroalkanes and arenes is not easy to achieve. Nevertheless, activation of the C-F bond in highly electron-deficient compounds such as 2,4,6-trifluoropyrimidine, pentafluoropyridine, or hexafluorobenzene is possible with stoichiometric amounts of bis(triethylphosphano) nickel(O) [101] (Scheme 2.45). More recently Herrmann and coworkers [102] have described a variant of the Kumada-Corriu cross-coupling reaction [103] between fluorobenzene and aryl Grignard compounds which uses catalytic amounts of nickel carbene complexes. Hammett analysis of the relative kinetic rate constants indicated that the reaction proceeds via initial oxidative addition of the fluoroaromatic reactant to the nickel(O) species. 

Scheme 14.10 The combined Suzuki-Miyaura or Kumada-Corriu cross-coupling reactions for the synthesis of polysubstituted aromatics.

Li - Magnesium Transmetallation. The Kumada-Corriu Cross-Coupling... 

Table 14,9 Selected DoM-Kumada-Corriu cross-coupling reactions forming Ar-Ar systems.

Scheme 14.12 O-Arylcarbamate-DoM-Kumada-Corriu cross-coupling pathways for poly-substituted naphthalenes [75].

Scheme 14.13) inherent in these transformations are considered for profitable exploitation in the Kumada-Corriu cross-coupling connection. 

Scheme 14.14 DoM of O-a lthiocarbamates, their Newman-Kwart rearrangement to S-a lthiocarbamate and their Kumada-Corriu cross coupling [79].

DoM-Kumada-Corriu Cross-Coupling for the Preparation of N,N-Diethyl-2-trimethylsilyl-3-phenylbenzamide (Table 14.10, entry 3)... 

Scheme 1.12 (a) General conditions for the Tamao-Kumada-Corriu cross-coupling reaction, (b) The proposed mechanism for the Tamao-Kumada-Corriu cross-coupling arylation procedure (note the base used is an alkoxide or hydroxide) [12a]. 

Scheme 1.13 The enantioselective catalytic variant of the Tamao-Kumada-Corriu cross-coupling reaction as developed by Hayashi et al. [30].

Figure 1.46 The Tamao-Kumada-Corriu cross-coupling of heteroaryl chlorides reported by Liu and Wang [165].

Tamao-Kumada-Corriu Cross-Coupling Reaction... 

When performing the Kumada-Corriu cross-couplings in the presence of an alkyl iodide such as /-PrI, a radical cross-coupling mechanism operates, allowing the performance of such cross-couplings at ambient temperature with less expensive aryl bromides (Scheme 2-8). The use of powerful Pd catalysts such as Pd(0)/5-Phos or PEPPSI is mandatory for achieving this radical-mediated cross-coupling. 

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