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Chan rearrangement : ウィキペディア英語版 | Chan rearrangement The Chan rearrangement is a chemical reaction that involves rearranging an acyloxy acetate (1) in the presence of a strong base to a 2-hydroxy-3-keto-ester (2). This procedure was rediscovered and employed in the Holton Taxol total synthesis. == Reaction mechanism ==
The methylene bridge in the reactant with adjacent carbonyl and acetyl substituents is acidic and can be deprotonated by strong non-nucleophilic bases such as lithium tetramethylpiperidide or lithium diisopropylamide (LDA) as in an aldol reaction. The thus formed enolate then gives a nucleophilic acyl substitution with the adjacent carbonyl of the acetyl group through a short lived intermediate oxirane. Acidic workup liberates the free hydroxyl group.
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「Chan rearrangement」の詳細全文を読む
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