Grignard reagents esters

Grignard reagent. Esters usually react with 2 moles of a Grignard reagent in this instance... 

Reaction of Esters with Grignard Reagents Esters and lactone react with 2 equivalents of a Grignard reagent to yield a tertiary alcohol in which two of the substituents are identical (Section 17.6). The reactioo occurs by the usual nucleophilic substitution mechanism to give an intermediate ketone, which reacts further with the Grignard reagent to yield a tertiary alcohol. ... 

When treated with a Grignard reagent, esters are reduced to yield alcohols with the introduction of two alkyl groups. 

Esters (a) and acid chlorides (6) readily react with Grignard reagents to give ketones, which immediately react with a second equivalent of the reagent as in (5) to give tertiary alcohols as before. 

The Reformatsky Reaction consists of the interaction of an ester of an a-halogeno-acid with an aldehyde, a ketone or another ester in the presence of zinc. For example, if a mixture of ethyl bromoacetate and benzaldehyde is heated with zinc, the latter undoubtedly first combines with the ethyl bromoacetate to form a Grignard-like reagent (reaction A), which then adds on to the benzaldehyde Just as a Grignard reagent would do (reaction B). The complex so formed, on acidification gives ethyl p-phenyl-p-hydroxy-propionate (reaction C). Note that reaction A could not satisfactorily be carried out using... 

Action of the Grignard reagent upon esters, for example ... 

Strictly speaking the alkyl halides are esters of the halogen acids, but since they enter into many reactions (t.g., formation of Grignard reagents, reaction with potassium cyanide to yield nitriles, etc.) which cannot be brought about by the other eaters, the alkyl halides are usually distinguished from the esters of the other inorganic acids. The preparation of a number of these is described below. 

Anilides or p-toluidides of acids from esters. Esters are converted into the corresponding anilides or p-toluidides by treatment with anilino- or with p-toluidino-magnesium bromide, which are readily obtained from any simple Grignard reagent and aniline or p-toluidine ... 

Alternatively, add a solution of 4 5 g. of p-toluidine in dry ether to the Grignard reagent prejjared from 1 0 g. of magnesium as detailed above. Then introduce 1 0 g. (or 0 02 mol) of the ester and proceed as described lOr anihdes. 

It is probable that the reaction proceeds through an organic zinc derivative, analogous to a Grignard reagent, formed by interaction of the a-halogen ester... 

The main use of organocadmium compounds is for the preparation of ketones and keto-esters, and their special merit lies in the fact that they react vigorously with acid chlorides of all types but add sluggishly or not at all to multiple bonds (compare addition of Grignard reagents to carbonyl groups). Some t3rpical syntheses are ... 

An alternative approach to this problem, providing two of the groups on the tertiaiy alcohol are the same, is to remove both in a single disconnection going back to an ester and two mols of the Grignard reagent ... 

Preparation of Tertiary Alcohols from Esters and Grignard Reagents... 

PREPARATION OF TERTIARY ALCOHOLS FROM ESTERS AND GRIGNARD REAGENTS... 

Tertiary alcohols can be prepared by a variation of the Grignard synthesis that uses esters as the source of the carbonyl group Methyl and ethyl esters are readily available and are the types most often used Two moles of a Grignard reagent are required per mole of ester the first mole reacts with the ester converting it to a ketone... 

The ketone is not isolated but reacts rapidly with the Grignard reagent to give after adding aqueous acid a tertiary alcohol Ketones are more reactive than esters toward... 

What combination of ester and Grignard reagent could you use to prepare each of the following tertiary alcohols ... 

Reaction of Grignard reagents with es ters (Section 14 10) Tertiary alcohols in which two of the substituents on the hy droxyl carbon are the same may be pre pared by the reaction of an ester with two equivalents of a Grignard reagent... 

We ve seen how Grignard reagents add to the carbonyl group of aldehydes ketones and esters Grignard reagents react m much the same way with carbon dioxide to yield mag nesium salts of carboxylic acids Acidification converts these magnesium salts to the desired carboxylic acids... 

Esters react with two equivalents of a Grignard reagent to produce terti ary alcohols Two of the groups bonded to the car bon that bears the hy droxyl group in the terti ary alcohol are derived from the Grignard re agent... 

Among the methods for preparing carboxylic acids carboxylation of a Grignard reagent and preparation and hydrolysis of a nitrile convert RBr to RCO2H The malonic ester synthesis converts RBr to RCH2CO2H... 

The organoborate intermediates can also be generated from alkenylboronic esters and alkyllithium or Grignard reagents, or from ttialkylboranes and alkenyllithium compounds. Conjugated symmetrical and unsymmetrical diynes (289—291), stereochemically pure 1,3-dienes (292,293), and 1,3-enynes (294) including functionali2ed systems can be prepared (289,295). 

Titanium alkyls, known as tamed Grignard reagents, do not add to esters, nitriles, epoxides, or nitroalkanes at low temperatures. Rather, they add exclusively ia a 1,2 fashion to unsaturated aldehydes (208—210). 

Other Rea.ctlons, The anhydride of neopentanoic acid, neopentanoyl anhydride [1538-75-6] can be made by the reaction of neopentanoic acid with acetic anhydride (25). The reaction of neopentanoic acid with acetone using various catalysts, such as titanium dioxide (26) or 2irconium oxide (27), gives 3,3-dimethyl-2-butanone [75-97-8] commonly referred to as pinacolone. Other routes to pinacolone include the reaction of pivaloyl chloride [3282-30-2] with Grignard reagents (28) and the condensation of neopentanoic acid with acetic acid using a rare-earth oxide catalyst (29). Amides of neopentanoic acid can be prepared direcdy from the acid, from the acid chloride, or from esters, using primary or secondary amines. 

---