Carboxylic acids organomagnesium compounds

At present, only two organomagnesium derivatives of terphenyl ligands have been well characterized. However, the first terphenyl magnesium compound was reported more than 60 years ago with the generation of BrMgTriph in solution and its subsequent reactions to give the carboxylic acid, the acetyl derivative, and triphenylbenzophenone.28... 

Although organomagnesium compounds are not sufficiently reactive to add to carboxylate anions, alkyllithium compounds add quite well. A useful synthesis of methyl ketones involves the addition of methyllithium to the lithium salt of a carboxylic acid ... 

The reactions of several carboxylic acid derivatives with organomagnesium and organolithium compounds were described in Section 14-12. The key step in these reactions is addition of the organometallic compound, as R60MS , to the carbonyl group. For a Grignard reagent,... 

The reaction of organomagnesium compounds with carbon dioxide to give carboxylates, and thence carboxylic acids, was one of the first to be reported by Grignard [4], and Grignard also observed the important side-reactions leading to ketones and t-alcohols [5] ... 

Synthesis of carboxylic acids by reaction of organomagnesium compounds with... 

Addition reactions. a,0-Unsaturated carbonyl compounds 1 and 3 undergo exclusive 1,4-addition reactions with organolithium (and organomagnesium) compounds owing to steric hindrance of the carbonyl group. The adducts 2 and 4 are converted into carboxylic acids by cleavage with potassium t-butoxide and H2O in the case of 2 see potassium r-hutoxidc, this volume) and by treatment with ethanolic... 

This disconnection represents the retro-Grignard reaction. It leads almost automatically to organomagnesium or lithium compounds as equivalents of carbanions and aldehydes or ketones as equivalents to the carbocation in the synthesis of alcohols (Scheme 2.35), or carbon dioxide in the synthesis of carboxylic acids. 

As nucleophiles, these compounds react with the electrophilic carbon atom of the carbonyl groups of aldehydes and ketones (Chapter 16) and of carboxylic esters and acid chlorides (Chapter 18). Herein lies the value of organomagnesium and organolithium reagents in synthetic organic chemistry—as carbon-centered nudeo-philes, they enable the formation of new carbon-carbon bonds. 

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