Magnesium Grignard reaction

Rieke magnesium contains MgXi 1178. Its role in promoting Rieke-magnesium Grignard reactions is not clear, but it could be catalytic. 

Triphenyl-carbinol, (C6H5)3COHy from Ethyl Benzoate and Phenyl Magnesium Bromide. (Grignard Reaction 6 (a).)... 

Commercial magnesium turnings for the Grignard reaction should be washed with sodium-dried ether to remove any surface grease which may be present, dried at 100°, and allowed to cool in a desiccator. 

Barbier reported (1) in 1899 that a mixture of methyl iodide, a methyl ketone, and magnesium metal in diethyl ether produced a tertiary alcohol. Detailed studies by his student Victor Grignard are documented in his now classical doctoral thesis, presented in 1901. Grignard estabUshed (2) that the reaction observed by Barbier could be separated into three distinct steps Grignard reagent formation, Grignard reaction, and hydrolysis. 

Aqueous work-up of the typical Grignard reaction gives a mixed magnesium hydroxide—haUde solution or suspension which must be disposed of. The cost of disposal of the acidic aqueous waste in accordance with local wastewater treatment regulations must also be considered. 

Reactions. The most noted magnesium alkyl reactions involve the solvated Grignard reagents. The more common reactions involving unsolvated magnesium alkyl are as foUows (14,15). 

Grignard reaction is the use of alkyl magnesium halides to form a host of products by reaction with a variety of chemicals... 

Anisole and mixtures of diethyl ether with aromatic hydrocarbons have both been widely employed as solvents for these reactions. Ethers other than diethyl ether and anisole have also been successfully used (cf. refs. 14-17). Hcxamethylphosphorotriamide has recently been used as a solvent for indole Grignard reactions. Young and Mizianty have recently described the use of an aromatic magnesium halide (phenylmagnesium bromide) for the synthesis of indole magnesium bromide. 

Brown et al. were not able to prepare 3-(prop-2-ynyl)indole [i.e., 3-propargylindole (49)] by the Grignard reaction however, Williamson and later Zenitz readily obtained 49 in satisfactory yield by the action of propargyl bromide on indole magnesium bromide in anisole. 

A modern variant is the intramolecular magnesium-ene reaction, e.g. the reaction of the alkene-allylic-Grignard compound 9 to give the five-membered ring product 10. This reaction proceeds regio- and stereoselectively, and is a key step in a synthesis of the sesquiterpenoid 6-protoilludene ... 

The starting material can be prepared in known manner from dibenzo[a,d] cyclohepta-1,4-diene-5-one by a Grignard reaction with 3-dimethylaminopropyl magnesium chloride, hydrolysis and dehydration of the resulting carbinol. 

A Grignard reaction begins with an acid-base complexation of Vfg2+ to the carbonyl oxygen atom of the aldehyde or ketone, thereby making the carbonyl group a better electrophile. Nucleophilic addition of R then produces a tetrahedral magnesium alkoxide intermediate, and protonation by addition of water... 

Fresh magnesium turnings for Grignard reaction can be used if suitable powder is unavailable, but initiation of reaction is likely to be prolonged, and the subsequent addition of the halide solution should occupy at least 30 minutes, longer if possible. 

Grignard reaction, addition of allyl-magnesium bromide to acrolein, 41,49... 

In some cases, the Grignard reaction can be performed intramolecularly. For example, treatment of 5-bromo-2-pentanone with magnesium and a small amount of mercuric chloride in THE produced 1-methyl-1-cyclobutanol in 60% yield. Other four- and five-membered ring compounds were also prepared by this procedure. Similar closing of five- and six-membered rings was achieved by treatment of a 6- or s-halocarbonyl compound, not with a metal, but with a dianion derived from nickel... 

A Grignard reaction between cyclohex-2-enone and diisopropyl magnesium chloride was carried out in a micro reactor yielding a keto and enol product each [168],... 

In the Grignard reaction, which is very important in the manufacture of a variety of fine chemicals, the continuous reactor for production of the reagent consists of a column of magnesium particles through which a solution of the organohalogen compound in an ether-class solvent is passed. The continuous mode of operation reduces side reactions, particularly Wurtz-type coupling, which make many reactions impractical. 

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