Mechanistic Studies of the Deslongchamps Annulation,The Journal of Organic Chemistry

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Mechanistic Studies of the Deslongchamps Annulation
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2018-01-12 00:00:00 , DOI: 10.1021/acs.joc.7b02341
Michael Kreibich ₁ , Denis Petrović _{1,

2} , Reinhard Brückner ₁

Affiliation

The Cs₂CO₃-mediated annulations (“Deslongchamps annulations”) of three spirocyclic benzoquinone monoketals 5b–d with an ester or acyl substituent at C-2 to two tert-butyl esters of γ,δ-unsaturated β-ketocarboxyl acids (“Nazarov reagents”; 2a,b) were monitored ¹H NMR spectroscopically. This revealed that a primary product, by all likelihood the Michael adduct, forms fast and prior to the appearance of the Deslongchamps adduct. These primary products form reversibly. This was proved by two crossover and four scavenging experiments. Therein, components already incorporated in one of the mentioned primary products ended up in Deslongchamps adducts different from the one, which would have resulted if the respective primary product had reacted alone. However, these experiments leave open whether our primary products are intermediates en route to Deslongchamps products or whether they represent dead ends.

中文翻译：

Deslongchamps环的机理研究

Cs ₂ CO ₃介导的三个螺环苯醌单缩酮5b – d（在C-2处具有酯或酰基取代基）与两个γ，δ-不饱和β-酮羧酸叔丁酯（“ Nazarov试剂”；2a，b）进行了监测¹1 H NMR光谱分析。这表明，主要的产物，很可能是迈克尔加合物，是在Deslongchamps加合物出现之前快速形成的。这些主要产品可逆地形成。这通过两次交叉和四个清除实验得到了证明。其中，已经包含在提到的一种主要产物中的组分最终在Deslongchamps加合物中得到了不同于那些在相应的主要产物中单独反应的产物。但是，无论我们的主要产品是去往Deslongchamps产品的中间产品还是它们代表死胡同，这些实验均未解决。

更新日期：2018-01-12

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