- Ligand- and copper-free Sonogashira and Heck couplings of (Het)aryl chlorides and bromides catalyzed by palladium nanoparticles supported on in situ generated Al(OH)3
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The ligand- and copper-free Sonogashira reaction of (Het)aryl halides (Br and Cl) with various terminal alkynes and the Heck coupling of (Het)aryl halides (Br and Cl) with a series of olefins, catalyzed by palladium nanoparticles supported on newly generated Al(OH)3, were developed. The catalyst can be readily recovered and reused 6 times without significant loss of activity and palladium leaching.
- Li, Xing,Gong, Xiaolei,Li, Zhipeng,Chang, Honghong,Gao, Wenchao,Wei, Wenlong
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p. 2475 - 2479
(2017/02/05)
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- Synthesis, structure and catalytic activity of xylylene-bridged dipalladium complexes with triazolylidene ligands
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A series of di-N-heterocyclic carbene (NHC) dipalladium complexes, [PdPyBr2]2(di-NHC) (2a–h), in which di-NHC represents a di-triazolylidene, featuring a 1,4-xylylene spacer between the carbene units, have been prepared from the reactions of the corresponding ditriazolium bromides with PdCl2 and excess NaBr as an additive in the presence of K2CO3 in pyridine. All of the complexes were fully characterized by NMR spectra, IR and elemental analyses. The molecular structure of 2b was determined by X-ray diffraction study, showing the intermolecular hydrogen bonding of Br···H–C. The influences of size of ligands on the catalytic activity have been investigated in the Heck reaction of styrene with bromobenzene. The complex 2g showed the best catalytic activity, and it is active for various aryl bromides with different electronic and steric properties and styrenes with both electron-donating and electron-withdrawing groups.
- Du, Yufeng,Liang, Beibei,Yang, Fenglei,Shi, Yanhui,Li, Xiuling,Pang, Guangsheng,Cao, Changsheng
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p. 193 - 201
(2017/03/16)
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- Transition-metal-free method for the synthesis of benzo[b]thiophenes from o -halovinylbenzenes and K2S via direct SNAr-type reaction, cyclization, and dehydrogenation process
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A new, highly efficient procedure for the synthesis of benzothiophenes from easily available o-halovinylbenzenes and potassium sulfide has been developed. The reaction tolerated a wide range of functionalities, and various 2-substituted benzo[b]thiophenes
- Zhang, Xiaoyun,Zeng, Weilan,Yang, Yuan,Huang, Hui,Liang, Yun
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p. 1687 - 1692
(2013/09/02)
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- Expeditious synthesis of fluorinated styrylbenzenes and polyaromatic hydrocarbons
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A series of fluorinated styrylbenzene derivatives were synthesized by the Mizoroki-Heck reaction using phosphine-free catalytic conditions or by adopting the one-pot Wittig-Heck reaction sequence. The fluorinated styrylbenzenes were converted into polyaromatic hydrocarbons such as phenanthrenes, [4]helicenes, and benzo[ghi]perylene by a modified photocyclization procedure involving I 2-THF condition.
- Bedekar, Ashutosh V.,Chaudhary, Anju R.,Shyam Sundar,Rajappa, Murali
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p. 392 - 396
(2013/02/23)
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- Easy-separable magnetic nanoparticle-supported Pd catalysts: Kinetics, stability and catalyst re-use
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A series of novel palladium-based catalysts supported on magnetic nanoparticles with diameters of 7- 17 nm have been prepared and evaluated in C-C coupling, hydrogenation and amination reactions. One type of catalyst used palladium complexes containing phosphine and/or acetate ligands for applications in Suzuki and Heck reactions. The second type consisted of Pd(0)-functionalised magnetic cores for use in hydrogenation and C-C coupling. Each type was effective for a range of reactions and was easily recoverable from the reaction mixture due to the superparamagnetic behaviour of the support. Detailed rate studies, found to correspond to pseudo-first-order kinetics, were conducted to assist in determining the mechanism of the reactions and showed that, during Heck reactions, Pd leaching is critically dependent on the presence of the aryl halide. The catalysts were found to retain their activity for several cycles although the rate of reaction was markedly reduced on re-use. Crown Copyright
- Laska, Urszula,Frost, Christopher G.,Price, Gareth J.,Plucinski, Pawel K.
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experimental part
p. 318 - 328
(2011/05/07)
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