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malonic ester synthesis
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. The major drawback of malonic ester synthesis is that the alkylation stage can also produce dialkylated structures. This makes separation of products difficult and yields lower.〔(Malonic Ester Synthesis – Alkylation of Enolates )〕
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==Mechanism==
The carbons alpha to carbonyl groups can be deprotonated by a strong base. The carbanion formed can undergo nucleophilic substitution on the alkyl halide, to give the alkylated compound. On heating, the di-ester undergoes thermal decarboxylation, yielding an acetic acid substituted by the appropriate R group.〔(【引用サイトリンク】 url = http://www.organic-chemistry.org/namedreactions/malonic-ester-synthesis.shtm )〕 Thus, the malonic ester can be thought of being equivalent to the −CH2COOH synthon.
The esters chosen are usually the same as the base used, i.e. ethyl esters with sodium ethoxide. This is to prevent scrambling by transesterification.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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