- Ligand-controlled iridium-catalyzed semihydrogenation of alkynes with ethanol: highly stereoselective synthesis of E- and Z-alkenes
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A ligand-controlled iridium-catalyzed semihydrogenation of alkynes to E- and Z-alkenes with ethanol was developed. Effective selectivity control was achieved by ligand regulation. The use of 1,2-bis(diphenylphosphino)ethane (DPPE) and 1,5-cyclooctadiene (COD) was critical for the stereoselective semihydrogenation of alkynes. The general applicability of this procedure was highlighted by the synthesis of more than 40 alkenes, with good stereoselectivities. The value of our approach in practical applications was investigated by studying the effects of pinosylvin and 4,4′-dihydroxystilbene (DHS) on zebrafish as a vertebrate model.
- Yang., Jinfei,Wang, Chengniu,Sun, Yufeng,Man, Xuyan,Li, Jinxia,Sun, Fei
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supporting information
p. 1903 - 1906
(2019/05/02)
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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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- Palladium-catalyzed desulfitative mizoroki-heck couplings of sulfonyl chlorides with mono-and disubstituted olefins: Rhodium-catalyzed desulfitative heck-type reactions under phosphine- And base-free conditions
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New conditions have been found for the desulfitative Mizoroki-Heck arylation and trifluoromethylation of mono- and disubustituted olefins with arenesulfonyl and trifluoro-methanesulfonyl chlorides. Thus (E)-1,2- disubstituted alkenes with high ster-eoselectivity and 1,1,2-disubstituted alkenes with 12:1 to 21:1 E/Z steroselectivity can be obtained. Herrmann's palladacycle at 0.1 mol% is sufficient to catalyze these reactions, for which electron-rich or electron-poor sulfonyl chlorides and alkenes are suitable. If phosphine- and base-free conditions are required. 1 mol% [RriCl(C 2,H4)2] catalyzes the desulfitative cross-cou pling reactions. Contrary to results reported for [RuCl2(PPh 3)2]-catalyzed coupling reactions with sulfonyl chlorides, the palladium and rhodium desulfitative Mizoroki-Heck coupling reactions are not inhibited by radical scavenging agents. Possible sulfones arising from the sulfonylation of alkenes at 60°C are not desulfitated at higher temperatures in the presence of the Pd or Rh catalysts.
- Dubbaka, Srinivas Reddy,Vogel, Pierre
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p. 2633 - 2641
(2007/10/03)
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- One-pot palladium-catalyzed highly chemo-, regio-, and stereoselective synthesis of trans-stilbene derivatives. A concise and convenient synthesis of resveratrol
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A convenient, efficient and highly chemo-, regio-, and stereoselective one-flask synthetic method is reported for the construction of unsymmetrical (or symmetrical) trans-stilbene derivatives based on two sequential Heck-type reactions using tetraalkylammonium salt-based catalyst systems and vinyltrimethylsilane as double bond equivalents. Resveratrol has thus been concisely synthesized.
- Jeffery, Tuyet,Ferber, Beno?t
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p. 193 - 197
(2007/10/03)
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- trans -> cis Photoisomerization of 1-Styrylnaphthalene and its 4'-Bromo- and 4'-Chloro-derivatives. A Fluorimetric and Laser Flash Photolytic Study
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The trans -> cis photoisomerization of 1-styrylnaphthalene (1-StN) and two para-halogen-substituted derivatives (Cl- and Br-1-StN) have been studied in solution by laser flash photolysis and by fluorimetric and photochemical methods.Measurements of the fl
- Elisei, Fausto,Mazzucato, Ugo,Goerner, Helmut
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p. 1469 - 1484
(2007/10/02)
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- SYNTHESIS OF DIARYLETHYLENES WITH CONDENSED RINGS BY THE WITTIG REACTION
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The Wittig reaction was used for the synthesis of diarylethylenes containing condensed naphthalene, anthracene, phenanthrene, and pyrene rings.Unlike 9-anthracenecarbaldehyde, which gives the trans isomers almost exclusively in the Wittig reaction with ar
- Listvan, V. N.,Gonchar, G. V.,Rudenko, E. S.,Onishchenko, T. A.,Stasyuk, A. P.
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p. 1528 - 1533
(2007/10/02)
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