Grignard’s reagent

In addition to its uses in photography and medicine, iodine and its compounds have been much exploited in volumetric analysis (iodometry and iodimetry, p. 864). Organoiodine compounds have also played a notable part in the development of synthetic organic chemistry, being the first compounds used in A. W. von Hofmann s alkylation of amines (1850), A. W. Williamson s synthesis of ethers (1851), A. Wurtz s coupling reactions (1855) and V. Grignard s reagents (1900). 

Victor Grignard France discovery of Grignard s reagent... 

By esterifying (+)2-octanol using a mixture of nitric and sulphuric acid, it was established that the nitrate produced did not undergo inversion. The (+)2-octyl nitrate obtained was heated during a period of 50 hr in a 10% alcoholic solution of sodium hydroxide. The optical rotation of all the reaction products was nil. Analysis by means of Grignard s reagent indicated 45.6% of 2-octanol, 39.8% of ketone and 14.6% of ether (by difference). A sample of the alcohol contained 76% of (+)2-octanol and 24% of racemate, i.e. 88% of (+)2-octanol and 12% of (—)2-octa-nol. 

Like nitrous esters, alkyl esters of nitric acid enter into reaction with a surplus of Grignard s reagent to form N-dialkylhydroxylamine. 

These compounds are obtained by treating Grignard s reagents with finely powdered selenium, when an addition compound results, which is decomposed by ice and hydrochloric acid and the arylselenomercaptan formed extracted as alkali salt from its ether solution, this salt then being condensed with sodium chloracetate in aqueous alcohol solution, the process being summarised as follows ... 

Alternatively, methane can be manufactured by the reaction of carbon monoxide and hydrogen in the presence of a nickel catalyst. Methane also is formed by reaction of magnesium methyl iodide (Grignard s reagent) in anhydrous ether with substances containing the hydroxyl group. Methyl iodide (bromide, chloride) is preferably made by reaction of methyl alcohol and phosphorus iodide (bromide, chloride). 

Grignard s Reagent. This reagent, which is fairly specific for dichloroethyl sulphide, was proposed by Grignard in 1918, but was kept secret until 1921. Detection is based on a double decomposition reaction of a type fairly frequent in organic chemistry ... 

Methyl boric acid, Me.B(OH)2.—Boric esters are best prepared by the action of alcohols on boric anhydride under pressure, and it lias been found that these esters react with Grignard s reagents to form the above type of compound, according to the equation ... 

In our method, the N,N-diethyl butadienyl carbamates (1) reacts both regio and stereospecifically to methyl vinyl ketone to give the cyclohexene (II) in 89% yield, which in turn adds the Grignard s reagent (III), again regio and ste-... 

R.N. Lewis and J.R. Wright (ref. 3) report that anisole, which is a slightly basic solvent, gives a quick reaction between Grignard s reagent and acetone. 

Davies and Kipping 1911. Davies and Kipping (see also Sect. 1.4) were the earliest protagonists of the one-step Barbier reaction at a time when the euphoria over the use of Grignard s reagent seemed to have blinded chemists to other synthetic possibilities. 

Scheme 10.22 Copper-catalyzed regioselective carbomagnesiation of enynes 74 with branched alkyl Grignard s reagents [22].

Scheme 10.25 Nickel-catalyzed carbomagnesiation of methylenecyclopropanes with aryl Grignard s reagents proximal carbon-carbon bond cleavage [26].

Scheme 10.27 Deuterium-labeling experiment in the nickel-catalyzed carbomagnesiation of MCP derivatives with vinyl Grignard s reagents [26].

Diastereoselective carbometallations of cyclopropenes as a new route to highly functionalized cyclopropanes have been reported [28]. The cyclopropene 93, bearing no substituents on the double bond, undergoes diastereoselective additions of aryl Grignard s reagents without a catalyst (Scheme 10.29a). On the other hand, the... 

In the studies reported up to date, various transition metal catalysts promoted the addition of primary alkyl, vinyl, aUyl, and aryl Grignard s reagents across carbon-carbon multiple bonds bearing no directing or activating substituents. 

Wang, Shi, and coworkers [70] reported the cobalt-catalyzed directed C-H alkylation of benzo[h]quinoHne with alkyl Grignard s reagents (Scheme 19.44). The reaction occurred at room temperature but proved less efficient and general than the corresponding C-H arylation. Interestingly, when isopropylmagnesium bromide was employed, a mixture of Hnear and branched products was obtained. The... 

In parallel to their work on the cobalt-catalyzed alkylation of secondary ben-zamides with alkyl chlorides (Scheme 19.36) [57], Nakamura and coworkers [71] reported a seemingly similar method with alkyl Grignard s reagents as the alkyl donors (Scheme 19.45). The reaction occurred at room temperature and under air, and furnished the mono- or bis-alkylated product selectively depending on the amide substituent. It was found to be also applicable to phenylpyridines and benzo[k]quinoline. 

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