Nickel-catalyzed arylation cross-coupling with Grignard reagents

As early as 1972, Kumada and coworkers reported that aryl chlorides could undergo cross-couplings with Grignard reagents catalyzed by a nickel-1,2-bis(diphenylpho sphino)ethane (dppe) complex (Equation 2.2) [9, 10]. 

In the area of organometallic chemistry, we begin with a procedure for the palladium-catalyzed animation of aryl halides and aryl triflates, illustrated by syntheses of N-HEXYL-2-METHYL-4-METHOXYANIUNE and N-METHYL-N-<4-CHLOROPHENYL)-ANILINE. The next procedure describes the synthesis of 1,2,3,4-TETRAHYDROCARBAZOLE by the palladium-catalyzed annulation of ketones with o-iodoaniline. Next, a procedure for the synthesis of 2,7-DIMETHYLNAPHTHALENE via the nickel-catalyzed coupling of aryl O-carbamates with Grignard reagents is presented. The fourth procedure in this section describes the synthesis of 5-METHYL-2,2 -BIPYRIDINE by a Negishi cross-coupling reaction... 

Nickel(II) salts are able to catalyze the coupling of Grignard reagents with alkenyl and aryl halides. A soluble 6 -phosphine complex, Ni(dppe)2Cl2, is a particularly effective catalyst.266 The main distinction between this reaction and Pd-catalyzed cross... 

In 1971, a year before the groups of Corriu and Kumada [5] independently reported the groundbreaking work on the topic of nickel-catalyzed cross-coupling reactions of aryl and vinyl halides with Grignard reagents, Tamura and Kochi described an iron-catalyzed vinylation reaction of Grignard reagents with vinyl halides (Scheme 5.1) [6]. 

Biaryls. Nickel complexes of the type NiCl2L2 catalyze the cross-coupling of sterically hindered aryl Grignard reagents with an aryl bromide to give biaryls in high yield as shown in the example. Thus 2-phenylmesitylene can be... 

In sharp contrast to the palladium- and nickel-catalyzed cross-couplings described above, iron catalysts show a high catalytic activity towards secondary alkyl halides, as reported by Nakamura and coworkers. Thus, cyclohexyl chloride, bromide or iodide can be arylated by a phenyl Grignard reagent in almost quantitative yield in the presence of FeCh as catalyst, along with an excess amount of a diamine additive N,N,N, N -tetramethylethylenediamine (TMEDA). Primary alkyl halides, such as octyl chloride, bromide and iodide, can also be arylated by the action of the same iron catalyst. However, the yields are somehow decreased, especially when primary alkyl chlorides are used as electrophiles (Equations 5.24 and 5.25) [33]. 

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