Catalysis by Amberlyst A-21: A Greener Approach to 4,5,6,7-Tetrahydro-1H-indazol-3(2H)-ones via Construction of Cyclohexanones

The 4,5,6,7-tetrahydro-1H-indazol-3(2H)-one derivatives have been synthesized in good yields via a two-step method in a single pot. The initial step involved the construction of cyclohexanone ring from aromatic aldehydes and β-ketoester in i-PrOH using an inexpensive and reusable catalyst (i.e., Amberlyst A-21) under mild reaction conditions. The utility of this catalyst has been demonstrated in synthesizing a range of cyclohexanone derivatives. The catalyst can be recovered and recycled, which makes this procedure simple, convenient, economically viable, and environmental friendly.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Catalysis of hydrosilylation: Part XXIV. H2PtCl6 in cyclohexanone as hydrosilylation catalyst—what is the active species in this catalytic system?

A cyclohexanone solution of H₂PtCl₆ was examined to find the catalytic species responsible for the hydrosilylation of the olefinic C=C bond. Similarly to other H₂PtCl₆–solvent systems (e.g. Speier's and Karstedt's catalysts), the real catalyst appeared to be colloidal platinum formed in situ by stepwise reduction [Pt(IV)→Pt(O)] and dechlorination of the platinum precursor. The role of cyclohexanone seems to be to form sufficiently stable platinum complexes to avoid rapid platinum precipitation and aggregation. The studies of H₂PtCl₆–solvent systems are of practical importance since these compounds are widely used catalyst precursors for hydrosilylation on an industrial scale.     

C2对称性有机小分子催化的高对映选择性Aldol反应

以环己酮与4-硝基苯甲醛直接不对称Aldol缩合为模型反应, 对一系列具有C2对称性的有机小分子催化剂进行了考察, 其中(2S,5S)-吡咯烷-2,5-二羧酸的不对称催化效果最好. 在10 ℃下, 以DMSO为溶剂, 30%摩尔分数催化剂用量, 研究了多个取代芳香醛和环己酮的不对称催化Aldol反应, 对映选择性为87%～99% ee.     

SBA-15负载硅钨酸催化环己酮Baeyer-Villiger氧化

采用浸渍法制备了H4O40SiW12/SBA-15催化剂,通过红外光谱、X射线衍射、N2吸附-脱附和透射电镜等方法对催化剂进行了表征.结果表明,H4O40SiW12能均匀分散于SBA-15的孔道中,催化剂仍保持载体的介孔结构和硅钨酸的Keggin型结构.将催化剂用于环己酮的Baeyer-Villiger氧化反应中,考察...     

含有螺环己烷结构的稠环斯德酮的合成

3-(3-芳基-3-羟基丙基)斯德酮在三氟化硼乙醚的催化作用下可以与环己酮发生类似于Oxa-Pictet-Spengler反应的成环反应,生成带有螺环己烷结构的稠环斯德酮.     

杂原子Sn-β分子筛的脱铝补位两步法制备、表征及其催化环己酮Baeyer-Villiger氧化性能

采用酸处理Al-β脱铝以产生T"空位",再高温焙烧插入Sn,即脱铝补位两步法制备了杂原子Sn-β分子筛.考察了β沸石中T"空位"数量、母体硅铝比和焙烧温度等因素对Sn-β分子筛形成与性能的影响,并利用X射线衍射、红外光谱、紫外-可见光谱、扫描电镜、X射线荧光光谱和电感耦合等离子体原子发射光谱等手段及环己酮Baeyer-Villiger(B-V)氧化反应,对催化剂进行了表征和评价.结果表明,脱铝补位两步法可以制备Sn-β分子筛,且Sn以四配位形式存在于分子筛骨架中,在对环己酮B-V氧化反应中表现出较高的催化活性.     

Preparation and characterization of H3−2(x+y)MnxCoyPMo12O40 heteropolysalts. Application to adipic acid green synthesis from cyclohexanone oxidation with hydrogen peroxide

H_3−2(x+y)Mn_xCo_yPMo₁₂O₄₀ heteropolysalts (x + y ≤ 3/2 and x, y: 0–1.5) were prepared by a cationic exchange method based on barium sulfate precipitation. Structural and textural properties of salts were examined by several physicochemical techniques such as infrared, scanning electron microscopy-energy dispersive X-ray, and ³¹P nuclear magnetic resonance spectroscopies, X-ray diffraction diffraction, and thermogravimetric analysis, and their catalytic properties were evaluated in the cyclohexanone oxidation using hydrogen peroxide (30%). The reaction products, adipic, glutaric, succinic, hexanoic, 6-hydroxyhexanoic, 7,7-dimethoxy, and heptanoic acids and 1,1-dimethoxy octane were identified by gas chromatography–mass spectrometry analysis. Only adipic, glutaric, and succinic acids were quantified by chromatography (high-performance liquid chromatography), the other products were noted X. Adipic acid (AA) is the major product for all systems. The effects of molar ratios of catalyst/reactant and cyclohexanol/cyclohexanone, heteropolysalt composition, and reaction duration on AA yield were investigated. The stability of the catalytic system was also examined. H_3−2(x+y)Mn_xCo_yPMo₁₂O₄₀ catalysts were found to be efficient for the cyclohexanone oxidation with conversions >95%. Among them, H₁Mn_0.25Co_0.75 exhibits the highest AA yield (75%).     

氧气催化氧化环己烷

本文系统综述了O₂氧化剂用于环己烷催化氧化体系的研究进展,包括金属配合物催化、金属纳米粒子催化、金属氧化物粒子催化、分子筛催化、碳材料催化、光促进催化、杂多酸催化、金属-有机骨架材料催化等。本文认为研究、开发以O₂为氧化剂,高活性高选择性的非均相环己烷催化氧化体系将成为今后环己烷催化氧化研究的主要方向,尤其是多金属甚至多元素复合体系。本综述不仅对开发高催化活性高选择性的环己烷催化氧化体系,改进目前工业上的环己醇环己酮制备工艺具有重要的参考价值,而且还对其他烃类C-H键和C-C键高效催化氧化体系甚至其他氧化体系的研究与开发也具有重要的参考价值。