Functionalized Grignard reagents metalation

Unfortunately, the preparation of functionalized Grignard reagents via direct oxidative addition of magnesium metal to organic halides still suffers from severe limitations. This is mainly due to the intrinsic high reducing potential of magnesium metal. 

The availability of functionalized Grignard reagents considerably enhances the scope of these reagents for performing cross-coupling reactions vith various transition metals. 

Sihcon chemistry also provides a means for preparing dendrimers capped with metal ions [3,65]. For example, ferrocene [78,79], Co +, [80], Ru [81], and [9] have been hnked to the periphery of sihcon-based dendrimers. These materials are prepared by displacing reactive Si-Cl functional groups with any of a variety of nucleophiles, such as amines, alcohols, or Grignard reagents, containing the metal complexes or hgands. 

The transition metal catalyzed carbon-carbon bond formation between organomagnesium reagents and aryl (vinyl) halides has been one of the pioneering entries into cross-coupling chemistry. The reaction has been widely utilized since than in azine chemistry,22 with the limitation that the functional group tolerance of Grignard reagents is only moderate. Here only some of the more recent developments will be mentioned. 

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