- S,O-Functionalized Metal-Organic Frameworks as Heterogeneous Single-Site Catalysts for the Oxidative Alkenylation of Arenes via C-H activation
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Heterogeneous single-site catalysts can combine the precise active site design of organometallic complexes with the efficient recovery of solid catalysts. Based on recent progress on homogeneous thioether ligands for Pd-catalyzed C-H activation reactions, we here develop a scalable metal-organic framework-based heterogeneous single-site catalyst containing S,O-moieties that increase the catalytic activity of Pd(II) for the oxidative alkenylation of arenes. The structure of the Pd?MOF-808-L1 catalyst was characterized in detail via solid-state nuclear magnetic resonance spectroscopy, N2 physisorption, and high-angle annular dark field scanning transmission electron microscopy, and the structure of the isolated palladium active sites could be identified by X-ray absorption spectroscopy. A turnover frequency (TOF) of 8.4 h-1 was reached after 1 h of reaction time, which was 3 times higher than the TOF of standard Pd(OAc)2, ranking Pd?MOF-808-L1 among the most active heterogeneous catalysts ever reported for the nondirected oxidative alkenylation of arenes. Finally, we showed that the single-site catalyst promotes the oxidative alkenylation of a broad range of electron-rich arenes, and the applicability of this heterogeneous system was demonstrated by the gram-scale synthesis of industrially relevant products.
- Bals, Sara,Bugaev, Aram L.,Dallenes, Jesse,De Vos, Dirk E.,Henrion, Micka?l,Krajnc, Andra?,Liu, Pei,Mali, Gregor,Soldatov, Alexander V.,Van Velthoven, Niels
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p. 5077 - 5085
(2020/05/27)
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- Attractive aerobic access to the α,β-unsaturated acyl azolium intermediate: Oxidative NHC catalysis via multistep electron transfer
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To replace high molecular weight oxidants with air (O2) we introduce multistep electron transfer NHC catalysis. The method provides a general and selective oxidation of the α,β-unsaturated aldehyde derived homoenolate to the synthetically useful α,β-unsaturated acyl azolium intermediate. Several independent oxidative NHC-catalyzed reactions are viable with this strategy and the products can be isolated in high to excellent yields.
- Ta,Axelsson,Sundén
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supporting information
p. 686 - 690
(2016/02/12)
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- A practical, efficient, and atom economic alternative to the Wittig and Horner-Wadsworth-Emmons reactions for the synthesis of (E)-α,β- unsaturated esters from aldehydes
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We describe a highly efficient new methodology for the synthesis of (E)-α,β-unsaturated esters from aldehydes. In our DMAP-catalyzed reaction, both aromatic as well as aliphatic aldehydes furnish the desired products highly regio- and stereoselectively if treated with commercially available or synthetically easily accessible malonic acid half ester. A large scale application in the synthesis of p-methoxycinnamates, which are of use as sunscreen ingredients, is described.
- List, Benjamin,Doehring, Arno,Hechavarria Fonseca, Maria T.,Job, Andreas,Rios Torres, Ramon
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p. 476 - 482
(2007/10/03)
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- SUNSCREEN COMPOSITIONS
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The present invention relates to improved sunscreen compositions, more preferably to improved sunscreen compositions containing at least one sunscreening agent (sunscreen) and a silicone-polyamide copolymer.
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- Sulphonic acids and their use as UV absorbers
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PCT No. PCT/EP96/04325 Sec. 371 Date Apr. 16, 1998 Sec. 102(e) Date Apr. 16, 1998 PCT Filed Oct. 4, 1996 PCT Pub. No. WO97/14680 PCT Pub. Date Apr. 24, 1997Sulphonic acids of formula (I) in which the components and indices have the meanings given in the description, are eminently suitable as u/v absorbers, especially in cosmetic sun-screening agents.
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- Indanylidene compounds, a process for their preparation and their use as UV absorbers
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Compounds of the formula I according to claim 1 are excellently suitable as UV absorbers for use in cosmetic products, in particular sunscreen compositions, daytime care products and hair care products. They are furthermore suitable for protection of products.
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- Use of benzazoles UV absorbers, new benzazoles and a process for their preparation
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Compounds which, per molecule, contain at least 2 benzazolyl groups are outstandingly suitable as UV absorbers for sunscreen compositions.
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