Kumada-Type Cross-Couplings

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-... 

Cross-coupling of arylmagnesium halides with fluorodiazines has been studied by Queguiner. Nickel catalysts were used for this Kumada-type process. The reactions work at room temperature in THE. Only one example on a 1,2-diazine core was studied, namely the coupling of 3-fluoro-6-phenylpyridazine with 4-methoxyphenylmagnesium bromide <2002JOC8991>. 

Fig. 51 Asymmetric Co-catalyzed Kumada-type cross-coupling reactions...

As was observed with the Kumada and Negishi reactions, the reactions conditions required to conduct the cross-coupling reaction may not be compatible with a wide variety of functional groups. The mild nature of the Suzuki reaction has been demonstrated by the types of functional groups that can be retained unprotected or via methods to modulate the reaction [65]. The coupling of 184 and 185 to generate 186 provided evidence that carboxylic acids and aldehydes are compatible with the Suzuki reaction. 

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. 

Branched terthiophene 5.77 was synthesized by Kumada-type cross-coupling of the Grignard reagent of 2-bromo-5-TMS-thiophene and 2,3-dibromothiophene in 79% yield. Higher generation DOTs were... 

Cross-couplings between organotin (Stille type), Grignard reagent (Kumada type), and aryl halide have been carried out using palladium over silica support. ... 

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