在这项工作中,意外地发现ZnO 2作为一种友好且可再生的无水过氧化氢来源,用于酸催化从羰基化合物合成环状有机过氧化物的过程中。特别是,五类环状有机过氧化物,即γ-氢过氧-γ-过氧内酯、β-氢过氧-β-过氧内酯、桥接臭氧化物、桥接1,2,4,5-四恶烷、三环单过氧化物和三环二过氧化物,使用由ZnO 2与H 2 SO 4反应原位产生的H 2 O 2以良好的产率合成。该方法方便、安全,并且不需要浓H 2 O 2水溶液或醚溶液。使用1wt%H 2 O 2溶液由乙酸锌合成起始ZnO 2。过氧化锌与硫酸在有机溶剂中反应,释放出过氧化氢并形成硫酸锌,硫酸锌通过形成一水合物相 ZnSO 4 ·H 2 O 作为干燥剂。 回收过氧化锌的可能性从一水合硫酸锌中得到的产物具有高产率。
Preparation of β-Substituted γ-Keto Esters by the Grignard Reaction on N-Acylpyrazoles
摘要:
Various gamma -keto esters were prepared by either the alcoholysis of N-(4-oxoalkcanoyl)pyrazoles or the Grignard replacement of pyrazole moiety of 4-(N-pyrazolyl)-4-oxoalkanoic esters. By using 3-phenyl-l-menthopyrazole as a chiral auxiliary, beta -substituted gamma -keto esters were enantioselectively obtained.
Synthesis of unstrained Criegee intermediates: inverse α-effect and other protective stereoelectronic forces can stop Baeyer–Villiger rearrangement of γ-hydroperoxy-γ-peroxylactones
作者:Vera A. Vil'、Yana A. Barsegyan、Leah Kuhn、Maria V. Ekimova、Egor A. Semenov、Alexander A. Korlyukov、Alexander O. Terent'ev、Igor V. Alabugin
DOI:10.1039/d0sc01025a
日期:——
by exploring the interplay between the primary and secondary stereoelectronic effects in the Baeyer–Villiger (BV) rearrangement by experimental and computationalstudies of γ-OR-substituted γ-peroxylactones, the previously elusive non-strained Criegee intermediates (CI). These new cyclic peroxides were synthesized by the peroxidation of γ-ketoesters followed by in situ cyclization using a BF3·Et2O/H2O2
在从不稳定的中间体中消除立体声电子保护时,我们可以将限制推到多远?我们通过对γ-OR取代的γ-过氧内酯(以前难以捉摸的Criegee中间体(CI))进行实验和计算研究,探索了Baeyer-Villiger(BV)重排中主要和次要立体电子效应之间的相互作用,从而解决了这个问题。 。这些新的环状过氧化物是通过γ-酮酸酯的过氧化反应,然后使用BF 3 ·Et 2 O / H 2 O 2系统原位环化而合成的。尽管主要影响(迁移的C–R m的排列带有断裂的O–O键的碳键在6元环中具有活性,次级作用的减弱(从OR孤对到断裂的C–R m键的捐赠)提供了足够的动力学稳定性,从而允许形成和分离稳定的γ-氢过氧-γ-过氧内酯,在C6-位带有甲基取代基。此外,源于两个新的立体电子因素的反应物稳定化也提供了补充保护,这两个因素在本工作中首次被确定和量化。首先,对γ-氢过氧-γ-过氧内酯的意料之外的偏爱削弱了主要的立体电子效应,并引入了约2
Lawesson,S.-O. et al., Acta Chemica Scandinavica (1947), 1962, vol. 16, p. 1191 - 1198
作者:Lawesson,S.-O. et al.
DOI:——
日期:——
Preparation of β-Substituted γ-Keto Esters by the Grignard Reaction on N-Acylpyrazoles
Various gamma -keto esters were prepared by either the alcoholysis of N-(4-oxoalkcanoyl)pyrazoles or the Grignard replacement of pyrazole moiety of 4-(N-pyrazolyl)-4-oxoalkanoic esters. By using 3-phenyl-l-menthopyrazole as a chiral auxiliary, beta -substituted gamma -keto esters were enantioselectively obtained.
Zinc peroxide as a convenient and recyclable source of anhydrous hydrogen peroxide and its application in the peroxidation of carbonyls
作者:Peter S. Radulov、Alexey A. Mikhaylov、Alexander G. Medvedev、Yana A. Barsegyan、Evgeny S. Belyaev、Victoria E. Dmitrieva、Tatyana A. Tripol'skaya、Elena A. Mel’nik、Vera A. Vil’、Ivan A. Yaremenko、Petr V. Prikhodchenko、Alexander O. Terent’ev
DOI:10.1039/d3nj05334b
日期:——
generated H2O2 from the reaction of ZnO2 with H2SO4. This approach is convenient, safe, and does not require a concentrated aqueous or ethereal solution of H2O2. The starting ZnO2 was synthesized from zinc acetate using a 1 wt% H2O2 solution. The reaction of zinc peroxide with sulfuric acid in an organic solvent results in the release of hydrogen peroxide and the formation of zinc sulfate, which acts as a
在这项工作中,意外地发现ZnO 2作为一种友好且可再生的无水过氧化氢来源,用于酸催化从羰基化合物合成环状有机过氧化物的过程中。特别是,五类环状有机过氧化物,即γ-氢过氧-γ-过氧内酯、β-氢过氧-β-过氧内酯、桥接臭氧化物、桥接1,2,4,5-四恶烷、三环单过氧化物和三环二过氧化物,使用由ZnO 2与H 2 SO 4反应原位产生的H 2 O 2以良好的产率合成。该方法方便、安全,并且不需要浓H 2 O 2水溶液或醚溶液。使用1wt%H 2 O 2溶液由乙酸锌合成起始ZnO 2。过氧化锌与硫酸在有机溶剂中反应,释放出过氧化氢并形成硫酸锌,硫酸锌通过形成一水合物相 ZnSO 4 ·H 2 O 作为干燥剂。 回收过氧化锌的可能性从一水合硫酸锌中得到的产物具有高产率。