Palladium-catalyzed arylation cross-coupling with Grignard reagents

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... 

A few palladium-catalyzed Kumada cross-couplings of heteroaryl chlorides have been reported [101]. Knochel has recently determined that certain 2-chloropyridine derivatives react with functionalized aryl Grignard reagents under mild conditions (Equation 2.61) [102]. 

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]. 

Table 4 Palladium/imidazolium salt-catalyzed cross-coupling of aryl halides with aryl Grignard reagents...

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