- Intramolecular Quenching of Carbonyl Triplets by β-Phenyl Rings
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The presence of a phenyl ring in a position β to the carbonyl of a phenyl alkyl ketone results in greatly reduced ketone triplet lifetimes.For example, in deaerated benzene solutions, triplet lifetimes were 2700 and 0.89 ns for propiophenone (P) and β-phe
- Wismontski-Knittel, T.,Kilp, T.
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- Nickel-Catalyzed Selective Synthesis of α-Alkylated Ketones via Dehydrogenative Cross-Coupling of Primary and Secondary Alcohols
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Herein, we describe an isolable, air-stable, homogeneous, nickel catalyst that performs dehydrogenative cross-coupling reaction between secondary and primary alcohols to result α-alkylated ketone products selectively. The sequence of steps involve in this one-pot reaction is dehydrogenation of both alcohols, condensation between the ketone and the aldehyde, and hydrogenation of the in situ-generated α,β-unsaturated ketone. Preliminary mechanistic investigation hints a radical mechanism following borrowing hydrogen reaction. (Figure presented.).
- Bains, Amreen K,Biswas, Ayanangshu,Adhikari, Debashis
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supporting information
p. 47 - 52
(2021/10/14)
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- Nickel-catalyzed α-alkylation of ketones with benzyl alcohols
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We reported an efficient method for α-alkylation of ketones with benzyl alcohols using the pyridine-bridged pincer-type N-heterocyclic carbenes nickel complexes as catalysts. A wide range of ketones and benzyl alcohols were efficiently converted into various alkylated products in moderate to high yields. In addition, these nickel complexes were also successfully applied for the synthesis of a wide range of quinoline derivatives.
- Wu, Di,Wang, Yubin,Li, Min,Shi, Lei,Liu, Jichang,Liu, Ning
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- BTP-Rh@g-C3N4 as an efficient recyclable catalyst for dehydrogenation and borrowing hydrogen reactions
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Highly active catalysts play an important role in modern catalysis. A novel and efficient ligand benzotriazole-pyrimidine (BTP) and the corresponding rhodium composite on C3N4 were successfully synthesized. The resulting rhodium composite was fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), thermogravimetric analysis (TGA), and x-ray photoelectron spectroscopy (XPS). The obtained composite exhibited good catalytic activity and good recovery performance in the synthesis of quinoxaline from 2-aminobenzyl alcohol and benzonitrile, and more than 20 quinoxalines were obtained in good yields. Additionally, it also showed that rhodium composite could achieved good catalytic performance in the synthesis of functionalized ketone through borrowing hydrogen strategy.
- Luo, Lan,Liu, Hongqiang,Zeng, Wei,Hu, Wenkang,Wang, Dawei
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- A Proton-Responsive Pyridyl(benzamide)-Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols
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A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.
- Kaur, Mandeep,U Din Reshi, Noor,Patra, Kamaless,Bhattacherya, Arindom,Kunnikuruvan, Sooraj,Bera, Jitendra K.
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supporting information
p. 10737 - 10748
(2021/06/15)
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- Direct conversion of secondary propargyl alcohols into 1,3-di-arylpropanoneviaDBU promoted redox isomerization and palladium assisted chemoselective hydrogenation in a single pot operation
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Palladium(ii)acetate is found to be an efficient catalyst for the single-step conversion of secondary propargyl alcohols to 1,3-diarylpropanone derivatives under mild basic conditions. The reaction is believed to proceedviaredox isomerisation of secondary propargyl alcohols followed by chemoselective reduction of an enone double bond with formic acid as an adequate hydrogen donor. A large number of 1,3-diarylpropanone derivatives may readily be prepared from a milligram to a multigram scale.
- Bera, Mrinal K.,Chandra, Shubhadeep,De, Rimpa,Savarimuthu, S. Antony
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p. 17871 - 17877
(2021/10/12)
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- Synthesis of α-Alkylated Ketones via Selective Epoxide Opening/Alkylation Reactions with Primary Alcohols
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A new method for converting terminal epoxides and primary alcohols into α-alkylated ketones under borrowing hydrogen conditions is reported. The procedure involves a one-pot epoxide ring opening and alkylation via primary alcohols in the presence of an N-heterocyclic carbene iridium(I) catalyst, under aerobic conditions, with water as the side product.
- Gen?, Serta?,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
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supporting information
p. 5229 - 5234
(2021/07/19)
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- Acylboronates in polarity-reversed generation of acyl palladium(II) intermediates
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We report a catalytic cross-coupling process between aryl (pseudo)halides and boron-based acyl anion equivalents. This mode of acylboronate reactivity represents polarity reversal, which is supported by the observation of tetracoordinated boronate and acyl palladium(II) species by 11B, 31P NMR, and mass spectrometry. A broad scope of aliphatic and aromatic acylboronates has been examined, as well as a variety of aryl (pseudo)halides.
- Trofimova, Alina,Holownia, Aleksandra,Tien, Chieh-Hung,?irvinskas, Martynas J.,Yudin, Andrei K.
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supporting information
p. 3294 - 3299
(2021/05/07)
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- Electrochemical-Induced Hydrogenation of Electron-Deficient Internal Olefins and Alkynes with CH3OH as Hydrogen Donor
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Efficient hydrogenation of electron-deficient internal olefins and alkynes access to saturate ketone with CH3OH as a single hydrogen donor under electrochemical conditions has been successfully developed. This hydrogenation strategy can be used to convert electron-deficient internal olefins and alkynes to saturate ketone under electrochemical conditions with exogenous-reductant and a metal catalyst. Mechanistic studies reveal that radical hydrogenation was involved in this transformation. Notably, various electron-deficient internal olefins and alkynes could be tolerated in such an electrochemical hydrogenation synthetic strategy and can be easily scaled up with good efficiency. (Figure presented.).
- Qin, Hongyun,Yang, Jianjing,Yan, Kelu,Xue, Yaxuan,Zhang, Meichen,Sun, Xuejun,Wen, Jiangwei,Wang, Hua
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supporting information
p. 2104 - 2109
(2021/03/15)
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- Selective catalytic synthesis of α-alkylated ketones and β-disubstituted ketones via acceptorless dehydrogenative cross-coupling of alcohols
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Herein, a phosphine-free pincer ruthenium(III) catalyzed β-alkylation of secondary alcohols with primary alcohols to α-alkylated ketones and two different secondary alcohols to β-branched ketones are reported. Notably, this transformation is environmentally benign and atom efficient with H2O and H2 gas as the only byproducts. The protocol is extended to gram-scale reaction and for functionalization of complex vitamin E and cholesterol derivatives.
- Bhattacharyya, Dipanjan,Sarmah, Bikash Kumar,Nandi, Sekhar,Srivastava, Hemant Kumar,Das, Animesh
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supporting information
p. 869 - 875
(2021/02/06)
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- Neutral-eosin Y-catalyzed regioselective hydroacylation of aryl alkenes under visible-light irradiation
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Styrene derivatives were hydroacylated with exclusive anti-Markovnikov selectivity by using neutral eosin Y as a direct hydrogen-atom-transfer (HAT) catalyst under visible-light irradiation. Aldehydes and styrenes with various substituents were tolerated (>20 examples), giving the corresponding products in moderate to high yields. The key acyl radical intermediate was generated from a direct HAT process induced by photoexcited eosin Y. Subsequent addition to styrenes and a reverse HAT process generated the ketone products.
- Liu, Haiwang,Xue, Fei,Wang, Mu,Tang, Xinxin,Wu, Jie
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supporting information
p. 406 - 410
(2020/12/30)
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- Unveiling the catalytic nature of palladium-N-heterocyclic carbene catalysts in the α-alkylation of ketones with primary alcohols
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We report herein the synthesis of four new Pd-PEPPSI complexes with backbone-modified N-heterocyclic carbene (NHC) ligands and their application as catalysts in the α-alkylation of ketones with primary alcohols using a borrowing hydrogen process and tandem Suzuki-Miyaura coupling/α-alkylation reactions. Among the synthesized Pd-PEPPSI complexes, complex2chaving 4-methoxyphenyl groups at the 4,5-positions and 4-methoxybenzyl substituents on the N-atoms of imidazole exhibited the highest catalytic activity in the α-alkylation of ketones with primary alcohols (18 examples) with yields reaching up to 95%. Additionally, complex2cwas demonstrated to be an effective catalyst for the tandem Suzuki-Miyaura-coupling/α-alkylation of ketones to give biaryl ketones with high yields. The heterogeneous nature of the present catalytic system was verified by mercury poisoning and hot filtration experiments. Moreover, the formation of NHC-stabilized Pd(0) nanoparticles during the α-alkylation reactions was identified by advanced analytical techniques.
- ?etinkaya, Bekir,Ero?lu, Zafer,Gülcemal, Süleyman,Metin, ?nder,Ovezova, Mamajan
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p. 10896 - 10908
(2021/08/17)
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- Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines
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Base-metal catalystsCo1,Co2andCo3were synthesized from designed pincer ligandsL1,L2andL3having NNN donor atoms respectively.Co1,Co2andCo3were characterized by IR, UV-Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures ofCo1andCo3. CatalystsCo1,Co2andCo3were utilized to study the dehydrogenative activation of alcohols forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates.
- Singh, Anshu,Maji, Ankur,Joshi, Mayank,Choudhury, Angshuman R.,Ghosh, Kaushik
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p. 8567 - 8587
(2021/06/30)
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- Cu(I) mediated hydrogen borrowing strategy for the α-alkylation of aryl ketones with aryl alcohols
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Abstract: New triazolium Schiff bases (TSBs) were synthesised via a simple and high throughput process. The new salts were successfully characterised. When reacted with Cu(CH3CN)4PF6, the TSB salts formed mononuclear triazole Schiff base copper(I) complexes and dinuclear complexes that were also characterised. The?copper complexes were generated in situ (mixtures of TSB salts with Cu(CH3CN)4PF6) and applied as homogeneous catalysts for the C–C coupling of a variety of aryl ketones with aryl alcohols, from which?significant reactivity was observed. Reaction conditions were optimised, and the results indicate that the catalyst systems are very robust. A catalyst concentration of 10?mol% efficiently and selectively catalysed the α-alkylation of methyl phenyl ketone and its derivatives to afford up to 94% yield of 1,3-diphenylpropan-1-one and its analogues. The process is adaptable with analogues of acetophenone and benzyl alcohol bearing various regulating substituents tolerated. Graphic abstract: [Figure not available: see fulltext.].
- Lawal, Nasir S.,Ibrahim, Halliru,Bala, Muhammad D.
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p. 275 - 285
(2021/02/09)
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- Highly Selective Hydrogenation of C═C Bonds Catalyzed by a Rhodium Hydride
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Under mild conditions (room temperature, 80 psi of H2) Cp*Rh(2-(2-pyridyl)phenyl)H catalyzes the selective hydrogenation of the C═C bond in α,β-unsaturated carbonyl compounds, including natural product precursors with bulky substituents in the β position and substrates possessing an array of additional functional groups. It also catalyzes the hydrogenation of many isolated double bonds. Mechanistic studies reveal that no radical intermediates are involved, and the catalyst appears to be homogeneous, thereby affording important complementarity to existing protocols for similar hydrogenation processes.
- Gu, Yiting,Lisnyak, Vladislav G.,Norton, Jack R.,Salahi, Farbod,Snyder, Scott A.,Zhou, Zhiyao
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supporting information
p. 9657 - 9663
(2021/07/19)
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- The: In situ fabrication of ZIF-67 on titania-coated magnetic nanoparticles: A new platform for the immobilization of Pd(ii) with enhanced catalytic activity for organic transformations
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Considering the outstanding characteristics of metal organic frameworks (MOFs) and magnetic nanoparticles, herein we report a facile approach for the synthesis of a magnetic zeolitic-imidazolate-framework-supported palladium(ii) catalyst. In brief, zeolitic imidazolate framework-67 (ZIF-67) was successfully incorporated onto the surface of titania-coated magnetic nanoparticles using ethane-1,2-diamine as a linker, and then Pd(ii) was immobilized onto this. The resulting Pd@ZIF-67-Fe3O4-TiO2 catalyst possesses a high surface area (205 m2 g-1), a large pore volume (0.10 cm3 g-1), good magnetic responsivity (10.71 emu g-1), and high stability. A comparative analysis of Pd@ZIF-67-Fe3O4-TiO2 and Pd@Fe3O4-TiO2 catalysts for the oxidation, reduction, and oxidative deprotection of oximes was done to investigate the effects of ZIF-67 on the catalytic performance of Pd species. Substantial differences in activity and stability were observed in the presence of ZIF-67, suggesting that ZIF-67 plays an important role in enhancing the activity of Pd(ii). This superior catalytic activity and stability arises due to a synergistic effect between well-dispersed palladium species and highly porous ZIF-67, which was confirmed via XPS analysis. Moreover, the catalyst retains its structure, chemical environment, and good magnetic response even after five catalytic runs, as confirmed via FTIR, XRD, XPS, and VSM studies of reused catalyst samples.
- Kaur, Manpreet,Paul, Satya,Sharma, Chandan,Sharma, Sukanya
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p. 20309 - 20322
(2021/11/22)
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- Transition metal complexes of a bis(carbene) ligand featuring 1,2,4-triazolin-5-ylidene donors: structural diversity and catalytic applications
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Dialkylation of the 1,3-bis(1,2,4-triazol-1-yl)benzene with ethyl bromide results in the formation of [L-H2]Br2which, upon salt metathesis with NH4PF6, readily yields the bis(triazolium) salt [L-H2](PF6)2with non-coordinating counterions. [L-H2](PF6)2and Ag2O react in a 1?:?1 ratio to yield a binuclear AgI-tetracarbene complex of the composition [(L)2Ag2](PF6)2which undergoes a facile transmetalation reaction with [Cu(SMe2)Br] to deliver the corresponding CuI-NHC complex [(L)2Cu2](PF6)2. In contrast, the [L-H2]Br2reacts with [Ir(Cp*)Cl2]2to generate a doubly C-H activated IrIII-NHC complex5. Similarly, the triazolinylidene donor supported diorthometalated RuII-complex6is also obtained. Complexes5and6represent the first examples of a stable diorthometalated binuclear IrIII/RuII-complex supported by 1,2,4-triazolin-5-ylidene donors. The synthesized IrIII-NHC complex5is found to be more effective than its RuII-analogue (6) for the reduction of a range of alkenes/alkynesviathe transfer hydrogenation strategy. Conversely, RuII-complex6is identified as an efficient catalyst (0.01 mol% loading) for the β-alkylation of a wide range of secondary alcohols using primary alcohols as alkylating partnersviaa borrowing hydrogen strategy.
- Donthireddy, S. N. R.,Illam, Praseetha Mathoor,Rit, Arnab,Singh, Vivek Kumar
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p. 11958 - 11970
(2020/09/21)
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- Direct C-H Arylation of Aldehydes by Merging Photocatalyzed Hydrogen Atom Transfer with Palladium Catalysis
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Herein, we report that merging palladium catalysis with hydrogen atom transfer (HAT) photocatalysis enabled direct arylations and alkenylations of aldehyde C-H bonds, facilitating visible light-catalyzed construction of a variety of ketones. Tetrabutylammonium decatungstate and anthraquinone were found to act as synergistic HAT photocatalysts. Density functional theory calculations suggested a Pd0-PdII-PdIII-PdI-Pd0 pathway and revealed that regeneration of the Pd0 catalyst and the photocatalyst occurs simultaneously in the presence of KHCO3. This regeneration features a low energy barrier, promoting efficient coupling of the palladium catalytic cycle with the photocatalytic cycle. The work reported herein suggests great promise for further applications of HAT photocatalysis in palladium-catalyzed cross-coupling and C-H functionalization reactions to be successful.
- Chen, Guangying,Cheng, Gui-Juan,Guo, Bin,Li, Xiaobao,Ran, Chongzhao,Wang, Lu,Wang, Ting,Wei, Jun-Jie,Zheng, Caijuan,Zheng, Chao
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p. 7543 - 7551
(2020/08/21)
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- Pentamethylphenyl (Ph*) and Related Derivatives as Useful Acyl Protecting Groups for Organic Synthesis: A Preliminary Study
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A study of acyl protecting groups derived from the Ph? motif is reported. While initial studies indicated that a variety of functional groups were not compatible with the Br 2-mediated cleavage conditions required to release the Ph? group, strategies involving the use of different reagents or a modification of Ph? itself (Ph*OH) were investigated to solve this problem.
- Cheong, Choon Boon,Frost, James R.,Donohoe, Timothy J.
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p. 1828 - 1832
(2020/10/06)
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- Utility of Organoboron Reagents in Arylation of Cyclopropanols via Chelated Pd(II) Catalysis: Chemoselective Access to β-Aryl Ketones
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Organoborane reagents were investigated as coupling partners to cyclopropanol-derived β-ketone enolates in the presence of a chelated Pd(II) catalyst. Efficient coupling of a range of electronically and sterically diverse cyclopropanols and aryl/alkenyl boronic derivatives (39 examples, 65-94% yield) could be achieved with the generation of synthetically important β-aryl ketone intermediates in a chemoselective fashion. This reactivity paradigm, which broadens the scope of aryl donor partners to homoenolates, allows open-flask conditions, water as a cosolvent, and preparation of halogen-bearing β-aryl ketones that are distinct from previous methods. This chelated Pd(II) catalysis appears to be different from the Pd(0) pathway, as evident from deuterium scrambling studies that could reveal differentiating protonolysis of an α-keto carbopalladium complex in the terminal step.
- Ilangovan, Andivelu,Ramar, Thangeswaran,Subbaiah, Murugaiah A. M.
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- Efficient Generation and Synthetic Applications of Alkyl-Substituted Siloxycarbenes: Suppression of Norrish-Type Fragmentations of Alkanoylsilanes by Triplet Energy Transfer
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Acylsilanes have been known to undergo isomerization to siloxycarbenes under photoirradiation and the thus generated carbenes can be utilized for various synthetic reactions. But this carbene formation is not necessarily efficient with some alkanoylsilanes because Norrish-type fragmentations compete, which limit the synthetic utility of alkanoylsilanes as carbene precursors. In this study, generation of siloxycarbenes from alkanoylsilanes by visible-light-induced energy transfer was examined by using an Ir complex, [Ir{dF(CF3)ppy}2(dtbpy)]PF6, and was successfully applied to the C?C coupling reactions with boronic esters or aldehydes. This methodology efficiently suppressed undesired Norrish-type reactions and broadened synthetic utility of alkanoylsilanes.
- Abe, Manabu,Hagiwara, Chihiro,Ishida, Kento,Kusama, Hiroyuki,Yamazaki, Hokuto
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p. 1249 - 1253
(2020/02/04)
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- Nickel-Catalyzed Deaminative Acylation of Activated Aliphatic Amines with Aromatic Amides via C-N Bond Activation
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Deaminative functionalization of aliphatic primary amines has great synthetic utility. Herein, we describe a Ni-catalyzed reductive deaminative cross-electrophile coupling reaction between Katritzky salts and aromatic amides. This work provides examples of the synthesis of various ketones from alkylpyridinium salts, including both primary and secondary alkylamines. Given its mild reaction conditions and high functional group tolerance, this cross-coupling strategy is expected to be useful for late-stage functionalization of complex compounds.
- Yu, Chu-Guo,Matsuo, Yutaka
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p. 950 - 955
(2020/02/15)
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- Preparation method of novel aromatic ketone compound
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The invention discloses a preparation method of a novel aromatic ketone compound. According to the preparation method, an aromatic carboxylic acid compound and an aromatic olefin compound are used asreaction raw materials, triphenylphosphine is taken as a deoxidizing reagent, Methylenene blue is taken as a photocatalyst, stirring and reacting are carried out at room temperature in an N,N-dimethylacetamide solvent under the irradiation of a white light lamp in a nitrogen atmosphere and under the condition of taking 2,4,6-trimethylpyridine as an alkali, thereby obtaining a target product, namely the aromatic ketone compound. The method has the advantages of mild reaction conditions, simplicity in operation, low cost, convenience in purification, environmental friendliness and the like.
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Paragraph 0015-0016
(2020/12/08)
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- Sustainable and Selective Alkylation of Deactivated Secondary Alcohols to Ketones by Non-bifunctional Pincer N-heterocyclic Carbene Manganese
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A sustainable and green route to access diverse functionalized ketones via dehydrogenative–dehydrative cross-coupling of primary and secondary alcohols is demonstrated. This borrowing hydrogen approach employing a pincer N-heterocyclic carbene Mn complex displays high activity and selectivity. A variety of primary and secondary alcohols are well tolerant and result in satisfactory isolated yields. Mechanistic studies suggest that this reaction proceeds via a direct outer-sphere mechanism and the dehydrogenation of the secondary alcohol substrates plays a vital role in the rate-limiting step.
- Lan, Xiao-Bing,Ye, Zongren,Liu, Jiahao,Huang, Ming,Shao, Youxiang,Cai, Xiang,Liu, Yan,Ke, Zhuofeng
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p. 2557 - 2563
(2020/05/04)
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- Method for synthesizing aryl ketone compound by taking TBADT as photocatalyst
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The invention provides a method for synthesizing an aryl ketone compound by taking TBADT as a photocatalyst. The method comprises the following steps: with TBADT as a photocatalyst, under the conditions of a palladium catalyst, a phosphine ligand, weak base and an organic solvent, irradiating the reactants under a 380-400 nm photocatalysis lamp at the room temperature under the inert protective atmosphere, so that an aldehyde group-containing compound reacts with Ar-X, wherein the Ar-X is aryl halide or aryl trifluoromethanesulfonate, and the aryl halide is aryl bromide or aryl iodide; the aldehyde group-containing compound is one of aryl aldehyde, alkyl aldehyde, linear primary aldehyde, acyclic secondary aldehyde and N-methylformamide. According to the invention, the tetrabutylammonium sebacate (TBADT)HAT photocatalyst and palladium catalysis are combined for use, and aldehyde C-H arylation and alkenylation reactions can be directly carried out to synthesize ketone. The method has the advantages of mild reaction conditions, high yield and wide substrate application range, and can be used for synthesizing natural products in medicinal plants.
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Paragraph 0040-0044; 0075-0082
(2020/09/21)
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- C-C coupling formation using nitron complexes
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A series of RuII (1), RhIII (2), IrIII (3, 4), IrI (5) and PdII (6-9) complexes of the 'instant carbene' nitron were prepared and characterized by 1H- and 13C-NMR, FT-IR and elemental analysis. The molecular structures of complexes 1-4 and 6 were determined by X-ray diffraction studies. The catalytic activity of the complexes (1-9) was evaluated in alpha(α)-alkylation reactions of ketones with alcohol via the borrowing hydrogen strategy under mild conditions. These complexes were able to perform this catalytic transformation in a short time with low catalyst and base amounts under an air atmosphere. Also, the PdII-nitron complexes (6-9) were applied in the Suzuki-Miyaura C-C coupling reaction and these complexes successfully initiated this reaction in a short time (30 minutes) using the H2O/2-propanol (1.5?:?0.5) solvent system. The DFT calculations revealed that the Pd0/II/0 pathway was more preferable for the mechanism
- Sevim, Mehmet,Kavukcu, Serdar Batikan,Kinal, Arma?an,?ahin, Onur,Türkmen, Hayati
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supporting information
p. 16903 - 16915
(2020/12/18)
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- Efficient Organoruthenium Catalysts for α-Alkylation of Ketones and Amide with Alcohols: Synthesis of Quinolines via Hydrogen Borrowing Strategy and their Mechanistic Studies
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A new family of phosphine free organometallic ruthenium(II) catalysts (Ru1–Ru4) supported by bidentate NN Schiff base ligands (L1–L4 where L1=N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazineylidene)methyl) aniline, L2=N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazineylidene)methyl)aniline, L3=N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-yl)hydrazineylidene)methyl)- aniline and L4=N,N-diethyl-4-((2-phenyl-2-(pyridin-2-yl)hydrazineylidene)methyl) aniline) was prepared and characterized. These half-sandwich complexes acted as catalysts for C?C bond formation and exhibited excellent performance in the dehydrogenative coupling of ketones and amides. In the synthesis of C–C bonds, alcohols were utilized as the alkylating agent. A broad range of substrates, including sterically hindered ketones and alcohols, were well tolerated under the optimized conditions (TON up to 47000 and TOF up to 11750 h?1). This ruthenium (II) catalysts were also active towards the dehydrogenative cyclization of o-amino benzyl alcohol for the formation of quinolines derivatives. Various polysubstituted quinolines were synthesized in moderate to excellent yields (TON up to 71000 and TOF up to 11830 h?1). Control experiments were carried out and the ruthenium hydride intermediate was characterized to support the reaction mechanism and a probable reaction pathway of dehydrogenative coupling for the C?C bond formation has been proposed.
- Maji, Ankur,Singh, Anshu,Singh, Neetu,Ghosh, Kaushik
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p. 3108 - 3125
(2020/05/18)
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- Ligand-tuned cobalt-containing coordination polymers and applications in water
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Ligands play a key role in modern catalysis research and occasionally determine whether a reaction will take place under specific conditions, such as in water. In this experiment, ligands containing an indole-based diacid moiety were employed to prepare the corresponding cobalt coordination polymer material (Co-CIA) and porous oval polymer material (Co-NCIA). Interestingly, it was observed that Co-CIA could promote the alkylation of ketones with alcohols and alcohols with alcohols, while Co-NCIA was effective for the synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazoles from various phenylenediamine and benzyl alcohols through borrowing hydrogen and dehydrogenation strategies. Other mechanism explorations, such as deuterium labeling experiments and a kinetics study, were conducted to better understand Co-CIA and Co-NCIA systems and the related transformations. Our studies provided an efficient method for the development of highly active cobalt coordination polymer materials with excellent recovery performance for dehydrogenation and borrowing hydrogen reactions under water and base-free conditions.
- Tao, Rong,Yang, Yike,Zhu, Haiyan,Hu, Xinyu,Wang, Dawei
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supporting information
p. 8452 - 8461
(2020/12/29)
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- Method for synthesizing alpha-alkylated ketone in water
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The invention discloses a method for synthesizing alpha-alkylated ketone in water. The method comprises the following steps: adding ketone, compound alcohol, a transition metal iridium catalyst, an alkali and a solvent, namely water into a reaction container, carrying out a reflux reaction on a reaction mixture in the air for several hours, carrying out cooling to room temperature, carrying out rotary evaporation to remove the solvent, and carrying out column separation (ethyl acetate/petroleum ether) to obtain a target compound, namely alpha-alkylated ketone. A reaction equivalent substrate is used in the reaction process, so raw material waste is avoided; equivalent alkali is used, so better environmental protection performance is obtained; water reflux reaction conditions are milder; and non-toxic and harmless pure water is used as the solvent in the reaction, only water is generated as a by-product, so atom reaction economy is high, and the requirements of green chemistry are met.
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Paragraph 0117-0121
(2020/08/22)
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- Iodine-catalyzed α,β-dehydrogenation of ketones and aldehydes generating conjugated enones and enals
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A transition metal-free α,β-dehydrogenation of ketones and aldehydes was developed. This reaction was conducted in a facile I2/KI/DMSO system to produce the corresponding unsaturated compounds in good to high yields. The gram-scale experiment also indicated the potential synthetic value of this new reaction in organic synthesis. In the reaction, DMSO acted as both solvent and mild oxidant.
- Cao, Yuanjie,Chen, Tieqiao,Huang, Tianzeng,Liu, Long
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supporting information
p. 8697 - 8701
(2020/06/08)
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- Synthesis and catalytic applications of Ru and Ir complexes containing N,O-chelating ligand
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A series of monometallic complexes (Ru1–3, Ir1–3) which have N,O-chelating ligand (pyrazine-2-carboxylate (1), pyridine-2-carboxylate (2), quinoline carboxylate(3) and bimetallic complexes (Ru4,5, Ir4,5) bridged by pyrazine-2,3- dicarboxylate (4) and imidazole-4,5-dicarboxylate(5) were synthesized and characterized by 1H-, 13C NMR, FT-IR, and elemental analysis. The crystal structure of Ir2 was determined by X-ray crystallography. The complexes (Ru1–5, Ir1–5) were applied to investigate the electronic and steric effect of ligand in their catalytic activities in transfer hydrogenation and alpha(α)-alkylation reaction of ketones with alcohols. The activities of iridium complexes (Ir1–5) were much more efficient than ruthenium complexes (Ru1–5). The highest activity for both reactions was observed for the complex (Ir2) with pyridine-2-carboxylate. The Ir hydride species was monitored for both reactions.
- Pakyapan, Bilge,Kavukcu, Serdar Bat?kan,?ahin, Zarife Sibel,Türkmen, Hayati
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- Chemoselective Hydrosilylation of the α,β-Site Double Bond in α,β- And α,β,γ,δ-Unsaturated Ketones Catalyzed by Macrosteric Borane Promoted by Hexafluoro-2-propanol
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The B(C6F5)3-catalyzed chemoselective hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones into the corresponding non-symmetric ketones in mild reaction conditions is developed. Nearly 55 substrates including those bearing reducible functional groups such as alkynyl, alkenyl, cyano, and aromatic heterocycles are chemoselectively hydrosilylated in good to excellent yields. Isotope-labeling studies revealed that hexafluoro-2-propanol also served as a hydrogen source in the process.
- Zhan, Xiao-Yu,Zhang, Hua,Dong, Yu,Yang, Jian,He, Shuai,Shi, Zhi-Chuan,Tang, Lei,Wang, Ji-Yu
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p. 6578 - 6592
(2020/07/17)
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- Ruthenium-Catalyzed β-Alkylation of Secondary Alcohols and α-Alkylation of Ketones via Borrowing Hydrogen: Dramatic Influence of the Pendant N-Heterocycle
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Three bidentate ruthenium(II) complexes with a pyridonate fragment were prepared and fully characterized. These complexes are structurally similar, but differ in their pendant substituents. Complex 1 contains a phenyl unit, whereas complexes 2 and 3 have uncoordinated thienyl and thiazolyl groups, respectively. These complexes were tested as catalysts for β-alkylation of secondary alcohols with primary alcohols, and 3 shows the highest activity, suggesting the thiazolyl ring participates in the catalytic process. Furthermore, 3 is an excellent catalyst for α-alkylation of ketones with primary alcohols. Various α-alkylated ketones were synthesized in high yields, by using 0.05 mol % 3 and 0.25 equiv of t-BuOK within 30 min.
- Zhang, Chong,Zhao, Jiong-Peng,Hu, Bowen,Shi, Jing,Chen, Dafa
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p. 654 - 664
(2019/02/17)
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- Unusual C-O bond cleavage of aromatic ethers in ruthenium complexes bearing a 2-alkoxypyridyl fragment
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Two tetradentate (NNOP) ruthenium products [{RO-C5H3N-C5H3N-CH(O)-C6H4-PPh2}Ru(CO)(PPh3)]Cl (1: R = Me; 3: R = Ph) were isolated by the reactions of the corresponding ligands with RuHCl(PPh3)3(CO). Complex 1 could also be transformed into 2 when heated in THF, through C-OMe bond cleavage. The mechanism of the unusual C-O cleavage in complex 1 was investigated, and the results indicate that it is an SN2 mechanism through the attack of trace amounts of neutral H2O. In contrast, in the presence of KOH, the reaction switches to an SNAr chemistry. The bidentate ruthenium isomers [{CH3O-C5H3N-C5H4N}RuH(CO)(PPh3)2]Cl (4a and 4b) could undergo similar C-O cleavage, affording product {O-C5H3N-C5H4N}RuH(CO)(PPh3)2 (5), which reacted with HCl to generate complex [{HO-C5H3N-C5H4N}RuH(CO)(PPh3)2]Cl (6). These complexes were tested as catalysts for β-alkylation of secondary alcohols with primary alcohols, and a series of β-alkylated 1-phenylethanol derivatives were isolated in high yields.
- Deng, Danfeng,Hu, Bowen,Yang, Min,Chen, Dafa
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supporting information
p. 13614 - 13621
(2019/09/30)
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- β-Amino Phosphine Mn Catalysts for 1,4-Transfer Hydrogenation of Chalcones and Allylic Alcohol Isomerization
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Mn complexes with amino acid derived PN ligands were used in the catalytic transfer hydrogenation (TH) of ketone and chalcone substrates in 2-propanol with mild heating. Moreover, chalcones are reduced selectively to the saturated ketone at short times and can be fully converted to the alcohol when reactions are prolonged. The mechanism of chalcone reduction was briefly considered. Allylic alcohols are not reactive in 2-propanol, but quantitative isomerization occurs in toluene. Thus, we suspect that the allylic alcohols are dehydrogenated and the resulting ketone is formed through a direct 1,4-hydrogenation of the chalcone. Finally, several other related ligands that have been used in Mn-based TH reactions were explored to test the viability of ligand design in favoring chemoselectivity. The β-amino phosphine ligands proved most effective in this regard.
- Vigneswaran, Vipulan,MacMillan, Samantha N.,Lacy, David C.
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supporting information
p. 4387 - 4391
(2019/11/14)
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- The role of phosphine ligands in the catalytic systems of the Heck reaction with aromatic carboxylic anhydrides
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The results of a comparative study of phosphine-containing and phosphine-free catalytic systems of the Heck reaction using aromatic carboxylic anhydrides as arylating agents are presented. It was demonstrated that the patterns of diff erential selectivity of the reaction under competition of two aromatic anhydrides or two alkenes are independent of the presence of a tertiary phosphine additive in the system. It was established that palladium complexes with no phosphine ligands in their coordination sphere are catalytically active at the step of activation of aromatic carboxylic anhydride and alkene. The patterns of diff erential selectivity for regioisomers of arylated products provide the evidence of the participation of phosphine-containing anionic palladium complexes in the regioselectivity-determining step of the catalytic cycle. The data obtained are in agreement with the phosphine involvement in the catalyst transformations proceeding outside the main catalytic cycle.
- Lagoda,Larina,Yarosh,Kurokhtina,Schmidt
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p. 817 - 824
(2019/06/03)
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- Iron-Catalyzed Tandem Three-Component Alkylation: Access to α-Methylated Substituted Ketones
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The borrowing hydrogen strategy has been applied in the synthesis of α-branched methylated ketones via a tandem three-component reaction catalyzed by a diaminocyclopentadienone iron tricarbonyl complex. Various alkyl and aromatic methyl ketones underwent dialkylation with various primary alcohols and methanol as alkylating agents in mild reaction conditions and good yields. Deuterium labeling experiments suggested that the benzylic alcohol was the hydrogen source in this tandem process.
- Bettoni, Léo,Seck, Charlotte,Mbaye, Mbaye DIagne,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
p. 3057 - 3061
(2019/05/10)
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- C?C Bond Formation of Benzyl Alcohols and Alkynes Using a Catalytic Amount of KOtBu: Unusual Regioselectivity through a Radical Mechanism
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We report a C?C bond-forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α-alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways.
- Kumar, Amit,Janes, Trevor,Chakraborty, Subrata,Daw, Prosenjit,von Wolff, Niklas,Carmieli, Raanan,Diskin-Posner, Yael,Milstein, David
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supporting information
p. 3373 - 3377
(2019/02/14)
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- Piano-stool Ru (II) arene complexes that contain ethylenediamine and application in alpha-alkylation reaction of ketones with alcohols
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A series of piano-stool Ru (II) complexes (Ru1–7) bearing ethylenediamine with aryl and aliphatic groups were prepared and fully characterized by 1H, 13C, 19F and 31P NMR spectroscopy, FT-IR and elemental analysis. The crystal structures of Ru2–4 and Ru7 were determined by X-ray crystallography. They were successfully applied to the alpha(α)-alkylation of aliphatic and aromatic ketones with alcohols via the borrowing hydrogen strategy in mild reaction conditions within a short time. The catalytic system has a broad substrate scope, which allows the synthesis of alpha alkylated ketones with excellent yields. The electronic and steric effects of complexes on catalytic activity were analysed. The influence of the carbon chain length of the ligand on the alpha-alkylation reaction of ketones was also investigated. The catalytic cycle was also examined by 1H-NMR spectroscopy in d8-toluene.
- Kavukcu, Serdar Bat?kan,Günnaz, Salih,?ahin, Onur,Türkmen, Hayati
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- Polymer-Anchored Bifunctional Pincer Catalysts for Chemoselective Transfer Hydrogenation and Related Reactions
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A series of polymer-supported cooperative PC(sp3)P pincer catalysts was synthesized and characterized. Their catalytic activity in the acceptorless dehydrogenative coupling of alcohols and the transfer hydrogenation of aldehydes with formic acid as a hydrogen source was investigated. This comparative study, examining homogeneous and polymer-tethered species, proved that carefully designing a link between the support and the catalytic moiety, which takes into consideration the mechanism underlying the target transformation, might lead to superior heterogeneous catalysis.
- Mujahed, Shrouq,Valentini, Federica,Cohen, Shirel,Vaccaro, Luigi,Gelman, Dmitri
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p. 4693 - 4699
(2019/10/28)
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- Reaction condition controlled nickel(ii)-catalyzed C-C cross-coupling of alcohols
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The challenge in the C-C cross-coupling of secondary and primary alcohols using acceptorless dehydrogenation coupling (ADC) is the difficulty in accurately controlling product selectivities. Herein, we report a controlled approach to a diverse range of β-alkylated secondary alcohols, α-alkylated ketones and α,β-unsaturated ketones using the ADC methodology employing a Ni(ii) 4,6-dimethylpyrimidine-2-thiolate cluster catalyst under different reaction conditions. This catalyst could tolerate a wide range of substrates and exhibited a high activity for the annulation reaction of secondary alcohols with 2-aminobenzyl alcohols to yield quinolines. This work is an example of precise chemoselectivity control by careful choice of reaction conditions.
- Zhang, Meng-Juan,Li, Hong-Xi,Young, David J.,Li, Hai-Yan,Lang, Jian-Ping
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supporting information
p. 3567 - 3574
(2019/04/14)
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- Ligand-controlled phosphine-free Co(II)-catalysed cross-coupling of secondary and primary alcohols
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Cobalt(II) complexes (5 mol% Co) bearing phosphine-free N?N?N pincer ligands efficiently catalyze C–C coupling of secondary and primary alcohols to selectively form α-alkylated ketones with a good functional group compatibility using NaOH (20 mol%) as a base at 120 °C. The NH group on the N?N?N–Co(II) precatalyst controls the activity and selectivity. This simple catalytic system is involved in the synthesis of quinolones via the dehydrogenative annulation of 2-aminobenzyl alcohols with secondary alcohols.
- Zhang, Shi-Qi,Guo, Bin,Xu, Ze,Li, Hong-Xi,Li, Hai-Yan,Lang, Jian-Ping
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- Selective Ketone Formations via Cobalt-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols
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A homogeneous cobalt-catalyzed β-alkylation of secondary alcohols with primary alcohols to selectively synthesize ketones via acceptorless dehydrogenative coupling is reported for the first time. Notably, this transformation is environmentally benign and atom economical with water and hydrogen gas as the only byproducts.
- Pandey, Bedraj,Xu, Shi,Ding, Keying
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supporting information
p. 7420 - 7423
(2019/10/02)
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- Electrochemical 1,4-reduction of α,β-unsaturated ketones with methanol and ammonium chloride as hydrogen sources
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A sustainable, chemoselective 1,4-reduction of α,β-unsaturated ketones by means of an electrochemical method is presented, wherein the extremely inexpensive ammonium chloride (NH4Cl) is applied as the only additive. The reaction proceeds smoothly in the air at ambient temperature. Mechanistic studies reveal that both NH4Cl and solvent methanol work as hydrogen donors.
- Huang, Binbin,Li, Yanan,Yang, Chao,Xia, Wujiong
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p. 6731 - 6734
(2019/06/17)
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- Arylation of Aldehydes to Directly Form Ketones via Tandem Nickel Catalysis
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A nickel-catalyzed arylation of both aliphatic and aromatic aldehydes proceeds with air-stable (hetero)arylboronic acids, with an exceptionally wide substrate scope. The neutral condition tolerates acidic hydrogen and sensitive polar groups and also preserves α-stereocenters of some chiral aldehydes. Interestingly, this nickel(0) catalysis does not follow common 1,2-insertion of arylmetal species to aldehydes and β-hydrogen elimination.
- Lei, Chuanhu,Zhu, Daoyong,Tangcueco, Vicente Iii Tiu,Zhou, Jianrong Steve
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supporting information
p. 5817 - 5822
(2019/08/26)
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- Chemoselective Hydrogenation of α,β-Unsaturated Carbonyls Catalyzed by Biomass-Derived Cobalt Nanoparticles in Water
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Herein, we report highly chemoselective hydrogenation of α,β-unsaturated carbonyls to saturated carbonyls catalyzed by cobalt nanoparticles supported on the biomass-derived carbon from bamboo shoots with molecular hydrogen in water, which is the first prototype using a heterogeneous non-noble metal catalyst for such organic transformation as far as we know. The optimal cobalt nanocatalyst, CoOx@NC-800, manifested remarkable activity and selectivity for hydrogenation of C=C in α,β-unsaturated carbonyls under mild conditions. A broad set of α,β-aromatic and aliphatic unsaturated carbonyls were selectively reduced to their corresponding saturated carbonyls in up to 99 % yields with good tolerance of various functional groups. Meanwhile, a new straightforward one-pot cascade synthesis of saturated carbonyls was realized with high activity and selectivity via the cross-aldol condensation of ketones with aldehydes followed by selective hydrogenation. More importantly, this one-pot strategy is applicable for the expedient synthesis of Loureirin A, a versatile bioactive and medicinal molecule, from readily available starting materials, further highlighting the practical utility of the catalyst. In addition, the catalyst can be easily separated for successive reuses without significant loss in both activity and selectivity.
- Song, Tao,Ma, Zhiming,Yang, Yong
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p. 1313 - 1319
(2019/01/25)
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- Proton-Coupled Electron Transfer: Transition-Metal-Free Selective Reduction of Chalcones and Alkynes Using Xanthate/Formic Acid
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Highly chemoselective reduction of α,β-unsaturated ketones to saturated ketones and stereoselective reduction of alkynes to (E)-alkenes has been developed under a transition-metal-free condition using a xanthate/formic acid mixture through proton-coupled electron transfer (PCET). Mechanistic experiments and DFT calculations support the possibility of a concerted proton electron-transfer (CPET) pathway. This Birch-type reduction demonstrates that a small nucleophilic organic molecule can be used as a single electron-transfer (SET) reducing agent with a proper proton source.
- Prasanna, Ramanathan,Guha, Somraj,Sekar, Govindasamy
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p. 2650 - 2653
(2019/04/17)
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- Nonbifunctional Outer-Sphere Strategy Achieved Highly Active α-Alkylation of Ketones with Alcohols by N-Heterocyclic Carbene Manganese (NHC-Mn)
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The unusual nonbifunctional outer-sphere strategy was successfully utilized in developing an easily accessible N-heterocyclic carbene manganese (NHC-Mn) system for highly active α-alkylation of ketones with alcohols. This system was efficient for a wide range of ketones and alcohols under mild reaction conditions, and also for the green synthesis of quinoline derivatives. The direct outer-sphere mechanism and the high activity of the present system demonstrate the potential of nonbifunctional outer-sphere strategy in catalyst design for acceptorless dehydrogenative transformations.
- Lan, Xiao-Bing,Ye, Zongren,Huang, Ming,Liu, Jiahao,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 8065 - 8070
(2019/10/11)
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- Controlling the selectivity and efficiency of the hydrogen borrowing reaction by switching between rhodium and iridium catalysts
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The catalytic alkylation of ketones with alcohols via the hydrogen borrowing methodology (HB) has the potential to be a highly efficient approach for forming new carbon-carbon bonds. However, this transformation can result in more than one product being formed. The work reported here utilises bidentate triazole-carbene ligated iridium and rhodium complexes as catalysts for the selective formation of alkylated ketone or alcohol products. Switching from an iridium centre to a rhodium centre in the complex resulted in significant changes in product selectivity. Other factors-base, base loading, solvent and reaction temperature-were also investigated to tune the selectivity further. The optimised conditions were used to demonstrate the scope of the reaction across 17 ketones and 14 alcohols containing a variety of functional groups. A series of mechanistic investigations were performed to probe the reasons behind the product selectivity, including kinetic and deuterium studies.
- Wang, Danfeng,McBurney, Roy T.,Pernik, Indrek,Messerle, Barbara A.
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supporting information
p. 13989 - 13999
(2019/10/01)
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- Nickel-Catalyzed Alkylation of Ketone Enolates: Synthesis of Monoselective Linear Ketones
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Herein we have developed a Ni-catalyzed protocol for the synthesis of linear ketones. Aryl, alkyl, and heteroaryl ketones as well as alcohols yielded the monoselective ketones in up to 90% yield. The catalytic protocol was successfully applied in to a gram-scale synthesis. For a practical utility, applications of a steroid derivative, oleyl alcohol, and naproxen alcohol were employed. Preliminary catalytic investigations involving the isolation of a Ni intermediate and defined Ni-H species as well as a series of deuterium-labeling experiments were performed.
- Das, Jagadish,Vellakkaran, Mari,Banerjee, Debasis
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supporting information
p. 769 - 779
(2019/01/24)
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- Synthesis and Structures of Arene Ruthenium (II)–NHC Complexes: Efficient Catalytic α-alkylation of ketones via Hydrogen Auto Transfer Reaction
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A panel of six new arene Ru (II)-NHC complexes 2a-f, (NHC?=?1,3-diethyl-(5,6-dimethyl)benzimidazolin-2-ylidene 1a, 1,3-dicyclohexylmethyl-(5,6-dimethyl)benzimidazolin-2-ylidene 1b and 1,3-dibenzyl-(5,6-dimethyl)benzimidazolin-2-ylidene 1c) were synthesized from the transmetallation reaction of Ag-NHC with [(η6-arene)RuCl2]2 and characterized. The ruthenium (II)-NHC complexes 2a-f were developed as effective catalysts for α-alkylation of ketones and synthesis of bioactive quinoline using primary/amino alcohols as coupling partners respectively. The reactions were performed with 0.5?mol% catalyst load in 8?h under aerobic condition and the maximum yield was up to 96%. Besides, the different alkyl wingtips on NHC and arene moieties were studied to differentiate the catalytic robustness of the complexes in the transformations.
- Balamurugan, Gunasekaran,Balaji, Sundarraman,Ramesh, Rengan,Bhuvanesh, Nattamai S.P.
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