Malonic ester synthesis of substituted acetic

Malonic Ester Synthesis of Substituted Acetic Acids... 

A MECHANISM FOR THE REACTION ] The Malonic Ester Synthesis of Substituted Acetic Acids 840... 

MALONIC ESTER SYNTHESIS OF R-SUBSTITUTED ACETIC ACIDS,... 

Synthesis of substituted acetic acid via malonic ester Malonic ester is an ester formed by reacting an alcohol with malonic acid (propanedicarboxylic acid). Following is the structure of diethyl malonate ... 

Synthesis of substituted acetic acids via acetoacetic ester... 146 Synthesis of substituted acetic acid via malonic ester. .. 150 a halo acids, a hydroxy acids, and a, (3 unsaturated acids.. .153... 

The malonic ester synthesis makes substituted derivatives of acetic acid. Malonic ester (diethyl malonate) is alkylated or acylated on the more acidic carbon that is a to both carbonyl groups, and the resulting derivative is hydrolyzed and allowed to decarboxylate. 

MALONIC ESTER SYNTHESIS OF R-SUBSTITUTED ACETIC ACIDS, RCH2COOH OR R(R ) CHCOOH (R could R)... 

The malonic ester synthesis makes substituted derivatives of acetic acid. Malonic... 

SYNTHESIS OF SUBSTITUTED ACETIC ACIDS THE MALONIC ESTER SYNTHESIS... 

The synthetic importance of the malonic ester synthesis follows from the fact that the substituted malonic ester can easily be hydrolyzed, and subsequently decarboxylates to yield a substituted acetic acid 9. This route to substituted acetic acids is an important method in organic synthesis ... 

Malonic esters have two ester groups, each of which may react as in the acetoacetic ester synthesis due to their similar structure (see the preceding section). The malonic ester synthesis provides a method for preparing a substituted acetic acid. Figure 15-14 shows the structure of one type of malonic ester. Figure 15-15 outlines the basic malonic ester synthesis. May repeat in that figure refers to the reaction with a second molecule of RX (or R X). 

The product of a malonic ester synthesis is a substituted acetic acid, with the substituent being the group used to alkylate malonic ester. In effect, the second carboxyl group is temporary, allowing the ester to be easily deprotonated and alkylated. Hydrolysis and decarboxylation remove the temporary carboxyl group, leaving the substituted acetic acid. 

The malonic ester synthesis converts a primary or secondary alkyl halide into a carboxylic acid with two more carbons (a substituted acetic acid). Identify the component that originates from malonic ester (the acid component). The rest of the molecule comes from the alkyl halide, which should be primary or methyl. 

Certain acid derivatives are capable of reactions involving intermediate carbanions. The malonic ester synthesis is used to synthesize substituted acetic acids. The reaction involves abstraction of... 

Hell-Volhard-Zelinsky (HVZ) reaction Reaction of a carboxylic acid with Br2 and PBr3 to give an a-bromo acyl bromide, often hydrolyzed to an a-bromo acid. (p. 1051) malonic ester synthesis Alkylation or acylation of malonic ester (diethyl malonate), followed by hydrolysis and decarboxylation, to give substituted acetic acids, (p. 1076)... 

The final step in the synthesis of all barbiturates consists in either condensation of a suitably substituted malonic or cyano-acetic ester with urea by means of sodium ethoxide (scheme a) or... 

Nucleophilic reactions at the carbon atoms of 1,3,4-thiadiazoles occur readily owing to the electron-deficient nature of this ring. Halo-substituted thiadiazoles are therefore highly activated and react with a wide range of nucleophiles. Carbon-based nucleophiles such as malonates have been used in the synthesis of 2-substituted thiadiazoles. When chlorothiadiazole 52 was treated with ethyl acetate in the presence of NaHMDS, the 2-phenyl-1,3,4-thiadiazol-5-ylacetic ester 53 was obtained (Equation 6) <20060L1447>. 

What is needed in the synthesis of C is a two-carbon nucleophile (or its equivalent) which is less basic titan an enolate so elimination is not competitive. If product C is recognized as an acetic acid derivative, then the following analysis can be made. A malonate ion used as the carbon nucleophile is much less basic than a simple ester enolate and hence undergoes substitution readily but does not promote elimination effectively, particularly in secondary systems. 

The value of malonate esters is illustrated in this synthesis of a substituted cyclic anhydride by conjugate addition to ethyl crotonate, hydrolysis, and decarboxylation, followed by dehydration with acetic anhydride. This route is very general and could be used to make a range of anhydrides with different substituents simply by ehoosing an appropriate unsaturated ester. 

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