Stille reaction nickel-catalyzed reactions

As previously mentioned. Section 5.4.1, Doster and Johnson have danonstrated that the nickel-catalyzed reaction of fluorinated arenes and pyridines with tributylvinyl-stannane provides new aryltributylstannanes via C—H functionalization with the loss of ethylene. This represents a useful alternative to the existing methods for the preparation of these valuable Stille coupling reagents (Schane 5.37). ... 

In spite of the novel encouraging results in acrylate dimerization, the technical exploitation is still a great challenge. The best turnover in the nickel catalyzed reaction are 400 cycles per nickel atom, obtained in a batch reactor after a reaction time of 72 h. All experiments showed that the catalyst decomposes during the reaction. 

The nickel-catalyzed reaction of a Grignard reagent with an aryl hahde, widely known as Corriu Kumada," constituted the first example of efficient crosscoupling reaction of aryl halides, long before the most popular Migjta Stille coupling. However, the classical protocol was not properly optimized and recent improvements were achieved using NHC Ni complexes. 

While the nickel-catalyzed reaction facilitates oxidative addition of substrates problematic to palladium-mediated processes, there is still a great deal of interest in the palladium-catalyzed Kumada cross-coupling reaction due to its enhanced chemoselectivity. Also, as mentioned previously, one distinct advantage of the palladium-catalyzed procedure, is that it allows versatile organolithium reagents to be used as an alternative to Grignard... 

Although the pioneering, systematic, and comprehensive experimental work of Wilke et al3,5 has led to a thorough understanding of the nickel-catalyzed cyclo-oligomerization reaction of 1,3-butadiene, there are still some essential mechanistic details that are not yet firmly established (vide infra). In the following account, we summarize recent progress in the... 

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

The number of examples of highly selective dehydrogenative silylation is still limited. The most convincing examples are Ru3(CO)i2- and Fe3(CO)i2-cata-lyzed reactions of styrene [106, 114] and vinylsilane [115] with HSiEts, RuH2(H2)2PCy3)2-catalyzed reaction of ethylene with HSiEt3 [116], and cationic rhodium complex-catalyzed dehydrogenative silylation, e.g., [117], as well as the nickel equivalent of the Karstedt catalyst [105]. 

A simple way to avoid toxic and intractable triorganotin waste is to use monoorganotin reagents that are much less toxic and less lipophilic. Unactivated secondary alkyl halides can be coupled with aryl-trichlorotin in a nickel-catalyzed Stille cross-coupling reaction" (e.g. Scheme 5.8.15). 

The relatively weak Ar-Br and especially Ar-I bonds would readily dissociate, giving rise to the Ni(I) paramagnetic complex and free aryl radical. This decomposition path is normally disfavored for aryl chlorides with considerably stronger Ar-Cl bonds. As a result, no Ni(I) species formed in the reactions of all chlo-roarenes studied, the only exception being [p-Me3NC6H4Cl]+. The p value of 5.4 obtained by Tsou and Kochi [33] is close to that (8.8 see above) previously reported by Foa and Cassar [32], suggesting that SET (Scheme 1) may play a certain role in some of the reactions of triphenylphosphine nickel(O) complexes with chloroarenes. It is still unclear if every reaction between any chloroarene and Ni(0) always involves the SET step. However, the excellent selectivity of the o-aryl Ni(II) complex formation from ArCl and highly reactive Ni(0) makes chloroarenes especially attractive substrates for various arylation reactions catalyzed by Ni complexes. 

Most of the catalytic cross-coupling reactions are based on the activation of a G-F bond of monofluorinated aromatic substrates. The Kumada-Gorriu-, Suzuki-, and Stille-type reactions are catalyzed by nickel or palladium complexes. 

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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