1536-23-8Relevant articles and documents
Aryl palladium carbene complexes and carbene-aryl coupling reactions
Albeniz, Ana C.,Espinet, Pablo,Manrique, Raul,Perez-Mateo, Alberto
, p. 1565 - 1573 (2005)
Transmetalation of an aminocarbene moiety from [W(CO) 5{C(NEt2)R}] to palladium leads to isolable monoaminocarbene palladium aryl complexes [{Pd(μ-Br)Pf[C(NEt 2)R]}2] (R = Me, Ph; Pf = C6F5). When [W(CO)5{C(OMe)R}] is used, the corresponding palladium carbenes cannot be isolated since these putative, more electrophilic carbenes undergo a fast migratory insertion process to give alkyl palladium complexes. These complexes could be stabilized in the η3-allylic form for R = 2-phenylethenyl or in the less stable η3-benzylic fashion for R = Ph. Hydrolysis products and a pentafluorophenylvinylic methyl ether (when R = Me) were also observed. The monoaminocarbenes slowly decompose through carbene-aryl coupling to produce the corresponding iminium salts and, depending on the reaction conditions, the corresponding hydrolysis products. The electrophilicity of the carbene carbon, which is mainly determined by the nature of the heteroatom group, controls the ease of evolution by carbene-aryl coupling. Accordingly, no carbene-aryl coupling was observed for a diaminocarbene palladium aryl complex.
London Dispersion Interactions Rather than Steric Hindrance Determine the Enantioselectivity of the Corey–Bakshi–Shibata Reduction
Eschmann, Christian,Song, Lijuan,Schreiner, Peter R.
supporting information, p. 4823 - 4832 (2021/02/01)
The well-known Corey–Bakshi–Shibata (CBS) reduction is a powerful method for the asymmetric synthesis of alcohols from prochiral ketones, often featuring high yields and excellent selectivities. While steric repulsion has been regarded as the key director of the observed high enantioselectivity for many years, we show that London dispersion (LD) interactions are at least as important for enantiodiscrimination. We exemplify this through a combination of detailed computational and experimental studies for a series of modified CBS catalysts equipped with dispersion energy donors (DEDs) in the catalysts and the substrates. Our results demonstrate that attractive LD interactions between the catalyst and the substrate, rather than steric repulsion, determine the selectivity. As a key outcome of our study, we were able to improve the catalyst design for some challenging CBS reductions.
A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
, p. 4617 - 4629 (2020/05/19)
We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
Method for preparing aromatic ketone in aqueous phase
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Paragraph 0042-0045, (2018/04/26)
The invention discloses a method for preparing aromatic ketone in an aqueous phase, comprising the following steps: enabling aryl formyl potassium formate and aryl potassium fluoborate to generate decarboxylation acylation reaction in water under the actions of a silver catalyst and an oxidizing agent, and performing treatment after reaction is ended to obtain the disclosed aromatic ketone. According to the preparation method, the silver catalyst replaces a noble metal catalyst, water is taken as a solvent, an aromatic ketone product is obtained with relatively high yield, the adopted catalystis low in cost and easy to obtain, reaction conditions are mild, and meanwhile, the product is good in university, and therefore, the method has good application potential.
