- Enantioselective Conjugate Addition of Stabilized Arylzinc Iodide to Enones: an Improved Protocol of the Hayashi Reaction
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Stabilised arylzinc iodide, prepared by direct insertion of zinc into aryl iodides, were used as nucleophiles in the Hayashi Rh-catalysed enantioselective conjugate addition to enones. The reaction conditions were optimized in the addition of phenylzinc i
- Casotti, Gianluca,Rositano, Vincenzo,Iuliano, Anna
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supporting information
p. 1126 - 1131
(2020/12/17)
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- Pd-Catalyzed Regio- and Stereoselective sp3 C?H Arylation of Primary Aliphatic Amines: Mechanistic Studies and Synthetic Applications
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The Pd-catalyzed γ-position sp3?C?H arylation of primary amines bearing an aliphatic chain or cycloalkyl substituent and related mechanistic studies are disclosed. 3-Bromo-2-hydroxybenzaldehyde plays a key role in γ-position sp3?C?H arylation as a transient directing group (TDG) to assist the regio- and stereoselective C?H activation of a Pd catalyst, and the development of a tandem reaction to transform 1°-amines into γ-aryl-substituted ketones demonstrates synthetic utility. Density functional theory (DFT)-based calculations revealed the detailed reaction mechanism and the origins of the high selectivity (γ-position and cis-only). The X-ray crystal structure of the isolated endo-palladacycle intermediate supported the DFT results, and a kinetic isotope experiment confirmed the results of DFT calculations indicating that the C?H activation step via simultaneous palladation and deprotonation is rate-determining.
- Ha, Hyeonbin,Choi, Ho Jeong,Park, Hahyoun,Gwon, Yunyeong,Lee, Jiin,Kwak, Jaesung,Kim, Min,Jung, Byunghyuck
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p. 1136 - 1145
(2021/02/12)
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- Palladium-catalyzed redox cascade for direct β-arylation of ketones
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Herein we report a full article about the detailed design and development of two palladium-catalyzed redox cascade methods that enable direct β-arylation of ketones. Palladium-catalyzed ketone dehydrogenation, aryl-X bond activation and conjugate addition were merged into a redox-neutral catalytic cycle. Non-metal-based aryl electrophiles were used as both the oxidant and the aryl source. The β-arylation with aryl iodides was achieved site-selectively with Pd(TFA)2/P(i-Pr)3 as the precatalyst and AgTFA as the iodide scavenger. Both cyclic and linear ketones can react to give β-aryl ketones with excellent functional group tolerance. The β-arylation with diaryliodonium salts was realized without stoichiometric heavy metal additives, and proved to be redox-neutral. A wider substrate scope regarding aryl groups and ketones was obtained for the arylation with diaryliodonium salts, and the possible involvement of palladium nanoparticles as the active catalyst was examined and discussed.
- Huang, Zhongxing,Dong, Guangbin
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supporting information
p. 3253 - 3265
(2018/05/04)
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- Palladium-Catalyzed Direct β-C?H Arylation of Ketones with Arylboronic Acids in Water
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A palladium-catalyzed direct β-C?H arylation of ketones was developed under mild conditions in water, featuring commercially available arylboronic acids as nucleophilic aryl sources and o-iodoxybenzoic acid as the oxidant. The method provides a concise route to access β-arylated ketones. Preliminary studies indicated that direct asymmetric β-C?H arylation of ketones could be achieved by this strategy. (Figure presented.).
- Hu, Xiaoyun,Yang, Xiaobo,Dai, Xi-Jie,Li, Chao-Jun
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supporting information
p. 2402 - 2406
(2017/07/22)
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- DIRECT B-ARYLATION OF CARBONYL COMPOUNDS
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Disclosed is a method for the β-C—H H functionalization of carbonyl compounds that is both selective and broadly applicable. The methods provide direct β-arylation of carbonyl compound with a diverse array of aryl or heteroaryl halides, aryl or heteroryl tosylate, aryl or heteroaryl triflates, or diaryliodonium salts, by palladium catalysis in the presence of a ligand and promoter.
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Paragraph 0123-0125; 128
(2016/09/12)
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- Palladium-catalyzed direct β-arylation of ketones with diaryliodonium salts: A stoichiometric heavy metal-free and user-friendly approach
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We herein report a new protocol for the Pd-catalyzed β-arylation of ketones without stoichiometric heavy metals. Widely accessible diaryliodonium salts are used as both the oxidant and aryl source. This tandem redox catalysis merges ketone dehydrogenation and conjugate addition without an additional oxidant or reductant. This transformation features the use of a unique bis-N-tosylsulfilimine ligand and the combination of potassium trifluoroacetate/trifluoroacetic acid to maintain an appropriate acidity of the reaction medium. The reaction tolerates both air and moisture, and shows a broad substrate scope. Kinetics studies, along with filtration and poisoning tests, support the involvement of palladium nanoparticles in the catalysis.
- Huang, Zhongxing,Sam, Quynh P.,Dong, Guangbin
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p. 5491 - 5498
(2015/09/28)
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- 1,4-Addition of aryl boronic acids to α,β-unsaturated ketones catalyzed by a CCC-NHC pincer rhodium complex
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An air- and water-stable CCC-NHC pincer Rh complex catalyzed the 1,4-addition of aryl boronic acids to α,β-unsaturated ketones and aldehydes. This bench top method proceeds in eco-friendly solvents including methanol and water. The scope of boronic acids was expanded to include heterocyclic examples.
- Reilly, Sean W.,Box, Hannah K.,Kuchenbeiser, Glenn R.,Rubio, Ramel J.,Letko, Christopher S.,Cousineau, Kandarpa D.,Hollis, T. Keith
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supporting information
p. 6738 - 6742
(2014/12/11)
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- Catalytic direct β-arylation of simple ketones with aryl iodides
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Herein we report a direct β-arylation of simple ketones with widely available aryl iodides, combining palladium-catalyzed ketone oxidation, aryl-halide activation, and conjugate addition through a single catalytic cycle. Simple cyclic ketones with different ring-sizes, as well as acyclic ketones, can be directly arylated at the β-position with complete site-selectivity and excellent functional group tolerance.
- Huang, Zhongxing,Dong, Guangbin
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p. 17747 - 17750
(2014/01/06)
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- Electrochemical Conversion of Functionalised Aryl Chlorides and Bromides to Arylzinc Species
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Electroreduction of aromatic chlorides or bromides in a cell fitted with a sacrificial zinc anode, in the presence of a nickel 2,2'-bipyridine complex affords the corresponding organozinc species in good yield.
- Sibille, Soline,Ratovelomanana, Victorin,Perichon, Jacques
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p. 283 - 284
(2007/10/02)
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