Grignard reagents alkyl halides

Metal alkyls can be prepared in a simple manner from the main group halides (X = Cl, Br, I) and the appropriate alkyl Grignard reagent (RMgl) or the alkyllithium salt (RLi), as shown for the cadmium alkyls (Equation (2)).13 The elimination of impurities from the precursor source is of great importance, as any remaining impurities are invariably carried over into the growing semiconductor layers. Incorporation of impurities, even at levels as low as 1015 free carriers per cubic centimeter (one part in ca. 107), can drastically affect the electronic properties of the... 

Recently, this reaction has been extensively studied since it is currently the only method to couple aryl Grignard reagents with secondary alkyl halides Indeed, secondary aUtyl halides do not react under palladium or nickel catalysis . On the other hand, let us recall that the coupling of secondary alkyl Grignard reagents with aryl halides leads to poor results (see above). 

Schlenk equilibrium concept sot forth above, the magnesium halide component of tertiary alkyl Grignard reagents causes halohydria formation faster than the diaJkylmagnesium component can add. Spocial conditions have, howover. been found, which permit addition of (erf-butylmagnesium chloride to ethylene oxide (Eq. 818), giving a modest yield of the desired primary alcohol.1484 1101... 

Telraorganotins, RaSn, prepared either by alkylation of tin halides with Grignard Reagents or alkyl lithium by reaction of an organic halide with a tin-sodium alloy by direct reaction of tin with an organic halide or by reaction of stannic chloride with alkyl aluminum compounds. 

The effect of the ligand on the stereochemical course of a reaction catalyzed by a transition metal compound can be significant. For example, in the nickel-catalyzed cross-coupling reactions of alkyl Grignard reagents and aryl halides, the effect of changing the ligands on the metal is summarized in Fig. 13 (66, 67). 

The metal-bound carbon atom in organopalladium(II) complexes can formally react either as an electrophile or as a nucleophile. Treatment of arylpalladium(II) complexes with alkyl halides, for example, yields products of homo- or cross-coupling, possibly via intermediate formation of hexacoordinated Pd(IV) complexes [31,33] (Scheme8.1). Treatment of the same type of complex with alkyl Grignard reagents or other carbon nucleophiles, on the other hand, also yields the corresponding alkyl arenes via nucleophilic displacement of a ligand followed by reductive elimination (Scheme 8.1). 

Even alkyl Grignard reagents can be coupled with alkyl halides 1 using iron catalysis with the xantphos ligand 11 (entry 16) [56]. The yields are acceptable for primary alkyl bromides. Secondary alkyl halides reacted only in low yield. 

Fig. 50 Cobalt-catalyzed cross-coupling of alkyl halides with Grignard reagents...

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