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The malonic ester synthesis is a chemical reaction where diethyl malonate or another ester of malonic acid is alkylated at the carbon alpha (directly adjacent) to both carbonyl groups, and then converted to a substituted acetic acid. [2] Reaction formula
One of the principal uses of this compound is in the malonic ester synthesis. The carbanion (2) formed by reacting diethyl malonate (1) with a suitable base can be alkylated with a suitable electrophile. This alkylated 1,3-dicarbonyl compound (3) readily undergoes decarboxylation with loss of carbon dioxide, to give a substituted acetic acid (4):
The Krapcho decarboxylation is a comparatively simpler method to manipulate malonic esters because it cleaves only one ester group, without affecting the other ester group. [1] The conventional method involves saponification to form carboxylic acids, followed by decarboxylation to cleave the carboxylic acids, and an esterification step to ...
Malonic acid is a dicarboxylic acid with structure CH 2 (COOH) 2. The ionized form of malonic acid, as well as its esters and salts, are known as malonates. For example, diethyl malonate is malonic acid's diethyl ester. The name originates from the Greek word μᾶλον (malon) meaning 'apple'.
Decarboxylations are an important in the malonic and acetoacetic ester synthesis. The Knoevenagel condensation and they allow keto acids serve as a stabilizing protecting group for carboxylic acid enols. [6] [page needed] [4]
The mechanism for the Gould–Jacobs reaction begins with a nucleophilic attack from the amine nitrogen follows by the loss of ethanol to form the condensation product. A 6 electron cyclization reaction with the loss of another ethanol molecule forms a quinoline (ethyl 4-oxo-4,4a-dihydroquinoline-3-carboxylate).
A notable method for synthesizing acetamidomalon ester is described in a 1950 patent, [1] which cites a procedure previously featured in Organic Syntheses. [2] The synthesis procedure involves the preparation of malonic acid diethyl ester in acetic acid combined with sodium nitrite (NaNO 2), resulting in diethyl isonitrosomalonate (also known as α-oximinomalonic acid diethyl ester).
Sodium ethoxide is commonly used as a base in the Claisen condensation [7] and malonic ester synthesis. [8] Sodium ethoxide may either deprotonate the α-position of an ester molecule, forming an enolate, or the ester molecule may undergo a nucleophilic substitution called transesterification. If the starting material is an ethyl ester, trans ...