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81.
Symmetrical azo compounds were synthesized from primary aromatic amines using n-BuMgBr as a base, oxygen as an oxidant, and CuCl2 as a catalyst. 相似文献
82.
Development of an Iron(II)‐Catalyzed Aerobic Catechol Cleavage and Biomimetic Synthesis of Betanidin
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Dr. Nicolas Guimond Dr. Peter Mayer Prof. Dr. Dirk Trauner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9519-9523
An aerobic iron(II)‐catalyzed cleavage of catechols was developed. This reaction allows for the preparation of 2‐methoxy‐2 H‐pyrans that can be employed as versatile building blocks for synthesis. The utility of this biomimetic oxidative cleavage is featured in the synthesis of betanidin, a natural colorant with antioxidant properties. 相似文献
83.
ZnII‐ and AuI‐Catalyzed Regioselective Hydrative Oxidations of 3‐En‐1‐ynes with Selectfluor: Realization of 1,4‐Dioxo and 1,4‐Oxohydroxy Functionalizations
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Dr. Appaso Mahadev Jadhav Sagar Ashok Gawade Dr. Dhananjayan Vasu Dr. Ramesh B. Dateer Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):1813-1817
Catalytic 1,4‐dioxo functionalizations of 3‐en‐1‐ynes to (Z)‐ and (E)‐2‐en‐1,4‐dicarbonyl compounds are described. This regioselective difunctionalization was achieved in one‐pot operation through initial alkyne hydration followed by in situ Selectfluor oxidation. The presence of pyridine alters the reaction chemoselectivity to give 4‐hydroxy‐2‐en‐1‐carbonyl products instead. A cooperative action of pyridine and ZnII assists the hydrolysis of key oxonium intermediate. 相似文献
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Theaerobicoxidationofethylenetoacetaldehydeandterminalolefinstocorrespondingalkan 2 onescat alyzedbypalladium(II)andcopper(IIorI)saltsarecol lectivelyknownasWackeroxidations (Scheme 1) .1Theyareveryimportantinbothsyntheticandindustrialchem istry .Treatmentoft… 相似文献
88.
Nanoscale iron‐doped zirconia solid‐solution aerogels are prepared via a simple ethanol thermal route using zirconyl nitrate and iron nitrate as starting materials, followed by a supercritical fluid drying process. Structural characteristics are investigated by means of powder X‐ray diffraction (XRD), thermal analyses (TG/DTA), N2 adsorption measurements and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results show that the resulting iron‐doped solid solutions are metastable tetragonal zirconia which exhibit excellent dispersibility and high solubility of iron oxide. Further, when the Fe:(Fe+Zr) ratio x is lower than 0.10, all of the Fe3+ ions can be incorporated into ZrO2 by substituting Zr4+ to form Zr1?xFexOy solid solutions. Moreover, for the first time, an additional hydroxyl group band that is not present in pure ZrO2 is observed by DRIFTS for the Zr(Fe)O2 solid solution. This is direct evidence of Fe3+ ions incorporated into ZrO2. These Zr1?xFexOy solid solutions are excellent catalysts for the solvent‐free aerobic oxidation of n‐hexadecane using air as the oxidant under ambient conditions. The Zr0.8Fe0.2Oy solid‐solution catalyst demonstrates the best catalytic properties, with the conversion of n‐hexadecane reaching 36.2 % with 48 % selectivity for ketones and 24 % selectivity for alcohols and it can be recycled five times without significant loss of activity. 相似文献
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Batch‐ and Continuous‐Flow Aerobic Oxidation of 14‐Hydroxy Opioids to 1,3‐Oxazolidines—A Concise Synthesis of Noroxymorphone
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Dr. Bernhard Gutmann Dr. Ulrich Weigl Dr. D. Phillip Cox Prof. Dr. C. Oliver Kappe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10393-10398
14‐Hydroxymorphinone is converted to noroxymorphone, the immediate precursor of important opioid antagonists, such as naltrexone and naloxone, in a three‐step reaction sequence. The initial oxidation of the N‐methyl group in 14‐hydroxymorphinone with in situ generated colloidal palladium(0) as the catalyst and molecular oxygen as the terminal oxidant constitutes the key transformation in this new route. This oxidation results in the formation of an unexpected oxazolidine ring structure. Subsequent hydrolysis of the oxazolidine under reduced pressure followed by hydrogenation in a packed‐bed flow reactor using palladium(0) as the catalyst provides noroxymorphone in high purity and good overall yield. To overcome challenges associated with gas–liquid reactions with molecular oxygen, the key oxidation reaction was translated to a continuous‐flow process. 相似文献