Grignard reagent with aldehydes and ketones

Reaction of Grignard reagents with aldehydes and ketones (Section 14 6)... 

Reactions of Grignard Reagents with Aldehydes and Ketones... 

The reactions of Grignard reagents with aldehydes and ketones give alcohols, reaction with acid chlorides and esters give tertiary alcohols, reaction with carbon dioxide to give carboxylic acids, reaction with nitriles give ketones, and reaction with epoxides give alcohols. 

Reaction of Grignard reagents with aldehydes and ketones (Section 14.6) A method that allows for alcohol preparation with formation of new carbon-carbon bonds. Primary, secondary, and tertiary alcohols can all be prepared. 

The key step in a basealdol reaction is nucleophilic addition of the enolate anion from one carbonyl-containing molecule to the carbonyl group of another carbonyl-containing molecule to form a tetrahedral carbonyl addition intermediate. This mechanism is illustrated by the aldol reaction between two molecules of acetaldehyde. Notice that OH is a true catalyst An OH is used in Step 1, but another OH is generated in Step 3. Notice also the parallel between Step 2 of the aldol reaction and the reaction of Grignard reagents with aldehydes and ketones (Section 12.5) and the first step of their reaction with esters (Section 14.7). Each type of reaction involves the addition of a carbon nucleophile to the carbonyl carbon of another molecule. 

Secondary and tertiary alcohols can be prepared by reacting a Grignard reagent with aldehydes and ketones, respectively, but these are not the only electrophiles that can be used with a Grignard. Grignards also have useful reactions with esters and epoxides. These reactions also give alcohol products, but they lead to alternate retrosynthetic strategies for certain alcohol TMs. 

Reaction of organolithium reagents with aldehydes and ketones (Section 14.7) Organolithium reagents react with aldehydes and ketones in a manner similar to that of Grignard reagents to form alcohols. 

Introduction. (1 R,25, 3/ ,45 )-3-Dimethylamino-1,7,7-trime-thylbicyclo[2.2.1 ]heptan-2-ol, herein referred to as (—)DAIB, has been shown to be an effective catalyst for enantioselective carbon-carbon bond formation utilizing dialkylzinc reagents with aldehydes and ketones. Attempts to utilize (—)DAIB for asymmetric inductions with other organometallic reagents such as aluminum alkyls, alkyl Grignards, and alkyl lithiums, have been unsuccessful. ... 

Let us try to get a broader picture of the synthesis of complicated alcohols. We learned (Sec. 15.12) that they are most often prepared by the reaction of Grignard reagents with aldehydes or ketones. In this chapter we Have learned that aldehydes and ketones, as well as the alkyl halides from which the Grignard reagents are made, are themselves most often prepared from alcohols. Finally, we know that the simple alcohols are among our most readily available compounds. We have available to us, then, a synthetic route leading from simple alcohols to more complicated ones. 

Complicated aldehydes and ketones are made by oxidizing complicated alcohols, By reaction with Grignard reagents these aldehydes and ketones can be converted into even more complicated alcohols, and so on. 

These compounds are sources of the nucleophilic anion RC=C and their reaction with primary alkyl halides provides an effective synthesis of alkynes (Section 9 6) The nucleophilicity of acetylide anions is also evident m their reactions with aldehydes and ketones which are entirely analogous to those of Grignard and organolithium reagents... 

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