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The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-ketoesters.〔Dieckmann, W. ''Ber.'' 1894, ''27'', 102 & 965〕〔Dieckmann, W. ''Ber.'' 1900, ''33'', 595 & 2670〕〔Dieckmann, W. ''Ann.'' 1901, ''317'', 51 & 93〕〔Davis, B. R.; Garrett, P. J. ''Comp. Org. Syn.'' 1991, ''2'', 806-829. (Review)〕 It is named after the German chemist Walter Dieckmann (1869–1925). The equivalent intermolecular reaction is the Claisen condensation. : ==Reaction Mechanism== The acidic hydrogen between the two carbonyl groups is deprotonated in step four. Protonation with a Brønsted-Lowry acid (H3O+ for example) re-forms the β-keto ester. This deprotonation step is the driving force for this reaction. : Owing to the steric stability of five- and six-membered ring structures, these will preferentially be formed. 1,4- and 1,6 diesters will form five-membered cyclic β-keto esters, while 1,5- and 1,7 diesters will form six-membered β-keto esters.〔(【引用サイトリンク】 Dieckmann Condensation )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dieckmann condensation」の詳細全文を読む スポンサード リンク
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