Magnesium insertion

Recently, a reductive magnesium insertion into a carbon-iodine bond of a / -iodo-a-ketoester has been described. The preparation of the iodomagnesium enolate 17 derived from an a-ketoester is the first preparation of such metallic species in this series. It was obtained from the reaction between the /1-iodo-a-ketoester precursor 16 and magnesium. In this case, the form of the metal is critical and magnesium powder with a large surface area is necessary (equation 6). 

The tires on the Hummer vehicles used in the Gulf War were made blowout-proof by strong, lightweight magnesium inserts. This is a photograph of a civilian model. 

Grignard reagents are used extensively in organic chemistry to assist in the formation of C-C bonds. For example, magnesium metal reacts with halocar-bons (or alkyl halides) such as bromomethane, in a solvent called ether. The magnesium inserts itself in between the carbon and halogen atoms, and each forms a covalent bond with magnesium. 

Scheme 5.1 Magnesium insertion into oiigofunctionaiized aryl halides and subsequent...

Essentially, an atom of magnesium inserts itself in between the C—Cl bond (this reaction works with other halides as well, such as Br or I). This magnesium atom has a significant electronic effect on the carbon atom to which it is attached. To see the effect, consider the alkyl halide (before Mg entered the picture) ... 

One of the remaining major drawbacks in the synthesis of functionalized aryl Grignard reagents is that magnesium insertion or halogen-magnesium exchange on electron-rich aryl halides is often problematic. 

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