- Palladium-catalyzed aerobic oxidative double allylic C-H oxygenation of alkenes: A novel and straightforward route to α,β-unsaturated esters
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A mild tandem oxidative functionalization of allyl aromatic hydrocarbons was accomplished using the catalytic system of Pd(OAc)2/DMA under 1 atm O2. The green twofold C-O bond formation involving double allylic C-H oxygenation unlocks opportunities for markedly different synthetic strategies. Moreover, the reaction affords aryl α,β-unsaturated esters directly from readily available terminal olefins in moderate to good yields with excellent chemo- and stereoselectivities.
- Yang, Wanfei,Chen, Huoji,Li, Jianxiao,Li, Chunsheng,Wu, Wanqing,Jiang, Huanfeng
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p. 9575 - 9578
(2015/06/08)
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- An Abnormal N-Heterocyclic Carbene-Based Palladium Dimer: Aqueous Oxidative Heck Coupling under Ambient Temperature
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Herein we report the synthesis of a new abnormal N-heterocyclic carbene (aNHC)-based ligand and its use in synthesizing an acetate bridged C-H activated palladium dimer (1). In complex 1, the carbene ligand displays an abnormal mode of binding with the palladium(II) ion. We used complex 1 as a catalyst for the oxidative Heck coupling reaction of arylboronic acids with electron-deficient as well as electron-rich olefins at ambient temperature in water to produce selectively the β-arylated products in good to excellent yields.
- Hota, Pradip Kumar,Vijaykumar, Gonela,Pariyar, Anand,Sau, Samaresh Chandra,Sen, Tamal K.,Mandal, Swadhin K.
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supporting information
p. 3162 - 3170
(2015/11/03)
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- Oxygen-promoted coupling of arylboronic acids with olefins catalyzed by [CA]2[PdX4] complexes without a base
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Abstract An efficient method was developed for the oxidative Heck reaction between arylboronic acids and olefins catalyzed by anionic palladium complexes of the type [CA]x[PdCl4] (x = 1,2) and [CA]2[Pd2Cl6] (CA = imidazolium or pyridinium cation). Molecular oxygen was employed as an environmentally benign oxidant to regenerate Pd(II) species during the reaction. The elaborated protocol could be applied to the coupling of different arylboronic acids with both electron-rich and electron-poor olefins. The catalyst system was further employed for the one-pot oxidative Heck reaction followed by the Heck coupling to build conjugated compounds in good yield. Mass spectrometry (ESI-MS) and UV-vis spectroscopy was used to identify palladium-containing complexes in the reactions. A plausible reaction mechanism of the oxidative Heck reaction was proposed.
- Silarska,Trzeciak
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- An efficient palladium(II) catalyst for oxidative Heck-type reaction under base-free conditions
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An efficient catalytic system for the palladium-catalyzed oxidative Heck reaction between arylboronic acids and various alkenes has been developed. Using the bis(aminoalkoxy)palladium complex of N,N-dimethylethanolamine as a catalyst, a series of substituted alkenes were obtained in moderate to excellent yields under mild reaction conditions. This protocol could be tolerated to arylboronic acids containing electron-donating or withdrawing groups and a wide range of olefins, such as acrylate, allyl esters, allyl ethers and alkenylphosphonate. A plausible reaction mechanism of the oxidative Heck reaction was proposed.
- Mi, Xia,Huang, Mengmeng,Guo, Hai,Wu, Yangjie
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p. 5123 - 5128
(2013/06/27)
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- Pd-catalyzed desulfitative Heck coupling with dioxygen as the terminal oxidant
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A Pd-catalyzed desulfitative Heck-type reaction of aromatic sulfinic acid sodium salts with various olefins is developed with O2 as the terminal oxidant under mild conditions. The presence of phosphane ligand DPEphos in anisole can significantly enhance the reaction selectivity.
- Zhou, Xianya,Luo, Jiaying,Liu, Jing,Peng, Shengming,Deng, Guo-Jun
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experimental part
p. 1432 - 1435
(2011/05/04)
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- Palladium nanoparticles on graphite oxide as catalyst for Suzuki-Miyaura, Mizoroki-Heck, and Sonogashira reactions
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Pd2+-Exchanged graphite oxide (GO) serves as a precatalyst for the formation of Pd-nanoparticles which are then deposited on the highly functionalized carbonaceous support. This versatile, air-stable, and ligand-free system was applied successfully to Suzuki-Miyaura couplings of some aryl chlorides and to the Mizoroki-Heck as well as the Sonogashira reaction showing relatively high activities and good selectivities. Like with other ligand-free supported systems, the reaction proceeded dominantly by a homogeneous mechanism, but attack of an aryl iodide to Pd-nanoparticles can be excluded as substantial contribution to the entire catalytic process. Beside its straightforward preparation and its stability in air, the system combines the advantages of both homogeneous and heterogeneous catalysis.
- Rumi, Luigi,Scheuermann, Gil M.,Muelhaupt, Rolf,Bannwarth, Willi
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experimental part
p. 966 - 976
(2011/08/05)
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