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首页> 外文期刊>Chemistry: A European journal >Formation of δ-Lactones with anti-Baeyer–Villiger Regiochemistry: Investigations into the Mechanism of the Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates
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Formation of δ-Lactones with anti-Baeyer–Villiger Regiochemistry: Investigations into the Mechanism of the Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates

机译：具有抗Baeyer-Villiger的δ-内酯的形成：调查β-氧化酯与烯醇乙酸盐的铈催化的有氧偶联机理

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摘要

The cerium-catalyzed, aerobic coupling of β-oxoesters with enol acetates and dioxygen yields δ-lactones with a 1,4-diketone moiety. In contrast to the Baeyer–Villiger oxidation (BVO), where the higher substituted residue migrates; in the case of this oxidative C-C coupling reaction, the less substituted alkyl residue undergoes a 1,2-shift. An endoperoxidic oxycarbenium ion comparable to the Criegee intermediate in the BVO is proposed as a reaction intermediate and submitted to conformational analysis by computational methods. As a result, the inverse regiochemistry is explained by a primary stereoelectronic effect. A Hammett analysis using different donor- and acceptor-substituted enol esters provides support for the oxycarbenium ion being the crucial intermediate in the rate determining step of the conversion. An overall mechanism is suggested with a radical chain reaction for the formation of endoperoxides from boxoesters, enol acetates and dioxygen with a cerium(IV) species as initiating reagent.
机译：用烯醇乙酸盐和二氧化铈的β-氧化酯的铈催化的有氧偶联产生δ-内酯，具有1,4-二酮部分。与Baeyer-Villiger氧化（BVO）相反，更高取代的残留物迁移;在该氧化的C-C偶联反应的情况下，较少取代的烷基残基经历1,2次。与BVO中的Criegee中间体相当的内氟氧基氧化碳离子作为反应中间体，并通过计算方法提交以构象分析。结果，通过初级立体电力效应来解释逆测定。使用不同供体和受体取代的烯醇酯的Hammett分析为氧羰烯离子提供了氧化氢中间体的速率确定转化率的关键中间体。提出了一种基团链条反应，用于将食谱，烯醇乙酸盐和二恶英与铈（IV）物种形成的内透铁氧化物作为引发试剂形成。

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