- Ligand-Promoted Palladium-Catalyzed C?H Acetoxylation of Simple Arenes
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The palladium-catalyzed C?H oxidation of simple arenes is an attractive strategy to obtain phenols, which have many applications in the fine chemicals industry. Although some advances have been made in this research area, low reactivity and selectivity are, in general, observed. This report describes a new catalytic system for the efficient C?H acetoxylation of simple arenes based on Pd(OAc)2 and a pyridinecarboxylic acid ligand.
- Valderas, Carolina,Naksomboon, Kananat,Fernández-Ibá?ez, M. ángeles
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p. 3213 - 3217
(2016/10/24)
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- Preparation of polyfunctional arylmagnesium, arylzinc, and benzylic zinc reagents by using magnesium in the presence of LiCl
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The presence of LiCl considerably facilitates the insertion of magnesium into various aromatic and heterocyclic bromides. Several functional groups, such as -OBoc, -OTs, -Cl, -F, -CF3, -OMe, -NMe2, and -N 2NR2, are well tolerated. The presence of a cyano group leads in some cases to competitive reduction of the organic halide to the corresponding ArH compound. The presence of sensitive groups such as methyl or ethyl ester is tolerated upon in situ trapping of the intermediate magnesium reagent with ZnCl2. This method can also be applied to the preparation of functionalized benzylic zinc reagents from benzylic chlorides. In the case of di- or tribromoaryl derivatives, directing groups such as -OPiv, -OTs, -N2NR2, or -OAc orient the zinc insertion (Zn/LiCl) to the ortho-position, while the reaction with Mg/LiCl or Mg/LiCl/ZnCl 2 leads to regioselective insertion into the para-carbon-bromine bond. Large-scale experiments (20-100 mmol) for all of the metalation procedures are described.
- Piller, Fabian M.,Metzger, Albrecht,Schade, Matthias A.,Haag, Benjamin A.,Gavryushin, Andrei,Knochel, Paul
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supporting information; experimental part
p. 7192 - 7202
(2010/03/05)
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- Polymer-supported gadolinium triflate as a convenient and efficient Lewis acid catalyst for acetylation of alcohols and phenols
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A polymer-supported gadolinium triflate (CMPS-IM-Gd) catalyst was prepared from chloromethyl polystyrene (CMPS) resin using a simple and convenient procedure. This polymeric catalyst was used as an efficient Lewis acid catalyst for the acetylation of various alcohols and phenols with acetic anhydride, affording high yields under mild conditions. The reaction was completed in a short period of time with small amounts of the catalyst. The catalyst was reused over 10 times without any significant loss of its catalytic activity.
- Yoon, Hyo-Jin,Lee, Sang-Myung,Kim, Jong-Ho,Cho, Hong-Jun,Choi, Jung-Woo,Lee, Sang-Hyeup,Lee, Yoon-Sik
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p. 3165 - 3171
(2008/09/20)
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- Directed ortho insertion (Dol): A new approach to functionalized aryl and heteroaryl zinc reagents
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A wide range of directing groups (ester, ketone, acetate, aryl sulfonate, triazene, carbamate) allow the regioselective directed ortho insertion (DoI) of zinc in the presence of LiCl leading to polyfunctional aryl and heteroaryl zinc reagents. Copyright
- Boudet, Nadege,Sase, Shohei,Sinha, Pradipta,Liu, Ching-Yuan,Krasovskiy, Arkady,Knoechel, Paul
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p. 12358 - 12359
(2008/03/30)
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- The Synthesis and Transition Temperatures of Ester Derivatives of 2-Fluoro-4-hydroxy- and 3-Fluoro-4-hydroxybenzonitriles also Incorporating Aliphatic Ring Systems
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The synthesis and liquid-crystal transition temperatures of forty ester derivatives of 2-fluoro-4-hydroxybenzonitrile and 3-fluoro-4-hydroxybenzonitrile are reported.The esters contain the trans-1,4-disubstituted cyclohexane or the 1,4-disubstituted bicyclooctane rings (some contain an additional phenyl ring).Many of the novel F-substituted esters exhibit substantially higher nematic-isotropic transition temperatures than the corresponding unsubstituted esters.The order of clearing points of these laterally substituted esters differing only in the presence of a benzene ring and the above-mentioned rings is established.
- Kelly, Stephen M.,Schad, Hanspeter
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p. 1580 - 1587
(2007/10/02)
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