Oxidative functional group transformations with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
作者:Noritaka Mizuno、Keigo Kamata、Kazuya Yamaguchi
DOI:10.1016/j.cattod.2011.07.007
日期:2012.5
equivalent H+ to form a bis-μ-hydroxo species [γ-PW10O38V2(μ-OH)2]3− (I′) in organic media. The strong electrophilic oxidants such as [γ-PW10O38V2(μ-OH)(μ-OOH)]3− (II) and [γ-PW10O38V2(μ-η2:η2-O2)]3− (III) are formed by the reaction of the bis-μ-hydroxo species with H2O2. In the presence of I and H+, H2O2-based oxidations such as (i) epoxidation of alkenes (17 examples including electron-deficient ones),
甲二钒取代的磷钨TBA 4 [γ-PW 10 ö 38 V 2(μ-OH)(μ-O)](我,TBA =四Ñ -butylammonium)与一种当量H起反应+以形成双- μ -hydroxo物种[γ-PW 10 ö 38 V 2(μ-OH)2 ] 3-(我')在有机介质中。强电氧化剂如[γ-PW 10 ö 38 V 2(μ-OH)(μ-OOH)] 3-(II)和[γ-PW 10 ö 38 V 2(μ-η 2:η 2 -O 2)] 3-(III)是通过用H双- μ-羟物种的反应形成2 Ò 2。在I和H +的存在下,基于H 2 O 2的氧化,例如(i)烯烃的环氧化(17个实例,包括缺电子的烯烃),(ii)烷烃的羟基化(11个实例),以及(iii)氧化烯烃,炔烃,并与溴芳烃的溴化-作为溴源(包括氯化的12个例子),化学,非对映体和区域选择性地以中等至高收率,高效率地利用H 2 O 2来产生相应的氧化产物。
Efficient Epoxidation of Electron-Deficient Alkenes with Hydrogen Peroxide Catalyzed by [γ-PW10O38V2(μ-OH)2]3−
epoxidized without formation of the corresponding amides. In addition, I could rapidly (≤10 min) catalyze epoxidation of various kinds of terminal, internal, and cyclic alkenes with H2O2 under the stoichiometric conditions. The mechanistic, spectroscopic, and kinetic studies showed that the I‐catalyzed epoxidation consists of the following three steps: 1) The reaction of I with H2O2 leads to reversible formation
甲二钒取代的磷钨,[γ-PW 10 ö 38 V 2(μ-OH)2 ] 3-(我),显示出最高的催化活性对H 2 ö 2中钒和钨络合物的乙酸烯丙酯的环氧化的基于营业额为210。在存在I的情况下,烯丙基位置带有乙酸盐,醚,羰基和氯基的各种缺电子烯烃可以高收率将其化学等价地氧化成相应的环氧化物,而等摩尔量的H 2 O 2关于基板。甚至丙烯腈和甲基丙烯腈也可以被环氧化而不形成相应的酰胺。另外,在化学计量比下,我可以快速(≤10分钟)用H 2 O 2催化各种末端,内部和环状烯烃的环氧化。的机理,光谱学,和动力学研究表明,我催化的环氧化反应由以下三个步骤组成:1)的反应我用H 2 ö 2所导致可逆形成一个氢过物种的[γ-PW 10 ö 38 V 2(μ-OH)(μ-OOH)] 3−(II),2)的连续脱水II形式的活性氧种与过氧组[γ-PW 10 ö 38 V 2(μ-η 2:η 2 -O 2)]
Highly selective and efficient olefin epoxidation with pure inorganic-ligand supported iron catalysts
efficient and selective epoxidation of alkenes via the design of specialized ligands, which facilitates to control the activity and selectivity of the reactions catalyzed by iron atom. Herein, we report the development of the olefinepoxidation with inorganic-ligand supported iron-catalysts using 30% H2O2 as an oxidant, and the mechanism is similar to iron-porphyrin type. With the catalyst 1, (NH4)3[FeMo6O18(OH)6]
在过去的二十年中,在过渡铁催化的烯烃选择性氧化为环氧化物方面取得了重大进展。在药物,分离的天然产物和精细化学品中发现的常见结构。这些方法中的许多已通过专门配体的设计实现了烯烃的高效和选择性环氧化,这有助于控制铁原子催化的反应的活性和选择性。本文中,我们报道了使用30%H 2 O 2作为氧化剂的无机配体负载的铁催化剂进行烯烃环氧化的研究进展,其机理与铁卟啉类型相似。对于催化剂1,(NH 4)3 [FeMo 6O 18(OH)6 ],各种芳族和脂肪族烯烃均以优异的收率以及化学和立体选择性成功地转化为相应的环氧化物。该催化体系具有能够避免使用昂贵的,有毒的,对空气/湿气敏感的和商业上不可用的有机配体的优点。该方法的通用性易于操作,具有较高的催化活性和优异的稳定性,这使其有可能在工业规模上使用,并可能为通过无机配体配位的铁催化进行催化氧化反应开辟一条道路。。
Olefin Epoxidation with Hydrogen Peroxide Catalyzed by Lacunary Polyoxometalate [γ-SiW10O34(H2O)2]4−
spectrometry show that reaction of I with excess hydrogen peroxide leads to fast formation of a diperoxo species, [TBA](4)[gamma-SiW(10)O(32)(O(2))(2)] (II), with retention of a gamma-Keggin type structure. Whereas the isolated compoundII is inactive for stoichiometric epoxidation of cyclooctene, epoxidation with II does proceed in the presence of hydrogen peroxide. The reaction of II with hydrogen peroxide
with TBA-I. The oxidation can be stopped immediately by removal of the solid catalyst, and vanadium and tungsten species can hardly be found in the filtrate after removal of the catalyst. These results rule out any contribution to the observed catalysis from vanadium and tungsten species that leach into the reaction solution, which means that the observed catalysis is truly heterogeneous in nature. In