Sonogashira nickel-catalyzed reactions

Transmetallation has been demonstrated to be the rate-hmiting step in the Sonogashira couphng reaction [291]. The transmetallation is also rate-determining in the nickel-catalyzed reaction between arylzinc reagents and a-chloro carbonyl compounds that proceeds via ArNi(II)R intermediates [292]. 

Other successful examples of catalysts containing NHC ligands are found in palladium- and nickel-catalyzed carbon-carbon bond formations. The catalyst development with these metals has focused in particular on Heck-type reactions, especially the Mizoroki-Heck reaction itself [Eq. (42)] and various cross coupling reactions [Eq. (43)], e.g., the Suzuki-Miyaura reaction ([M] = and the Kumada-Corriu reaction ([M] = MgBr). " Related reactions like the Sonogashira coupling [Eq. (44)]326-329 Buchwald-... 

An analogous nickel catalyzed coupling was also reported recently, where 3-, and 4-cyanopyridine were coupled with different ethynylzinc derivatives in the presence of a nickel-phosphine catalyst system (7.43.),61 Although this reaction is not a Sonogashira coupling, it constitutes an efficient alternative approach to ethynylpyridines. It is also interesting to... 

Fig. 3 Hiyama, Kumada-Corriu, Stille, Sonogashira, and other nickel-catalyzed coupling reactions...

Beletskaya, I. P., Latyshev, G. V., Tsvetkov, A. V., Lukashev, N. V. The nickel-catalyzed Sonogashira-Hagihara reaction. Tetrahedron Lett. 2003,44, 5011-5013. 

In 2008 Bhanage s team reported on a copper-catalyzed carbonylative Sonogashira reaction of aryl iodides [68]. In this procedure, copper bis(2,2,6,6-tetra-methyl-3,5-heptanedionate) [Cu(TMHD)2] was used as the catalyst for this transformation and using NEta as a base. Alkynones were produced in good yields (Scheme 5.33). A nickel-catalyzed carbonylation of allyl halides and acetylenes was reported on by Moreto and colleagues [69]. Cyclopentane skeletons were produced in high yields and with controlled stereochemistry. 

Nickel-Catalyzed Alkylation of Alkynes with Alkyl Halides, Nickel-Catalyzed Sonogashira Reaction... 

Besides palladium catalysts, nickel was also found to be an effective catalyst for the Sonogashira reaction in aqueous media. Recently, Beletskaya et al. reported a Ni(PPh3)2Cl2/CuI-catalyzed Sonogashira coupling reaction of terminal acetylenes with aryl iodides in aqueous dioxane in high yields (Eq. 4.19).39... 

Three additional processes, the Stille, Suzuki, and Sonogashira reactions, further broaden the scope of transition metal-catalyzed bond-forming processes. All utilize catalytic palladium or nickel the differences lie... 

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