- Trialkylammonium salt degradation: Implications for methylation and cross-coupling
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Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
- Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
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p. 6949 - 6963
(2021/06/02)
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- Suzuki coupling of aroyl-MIDA boronate esters – A preliminary report on scope and limitations
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Recent methodological reports for synthesizing acyl-MIDA boronate esters compel an investigation of their potential use as substrates in a standard Suzuki-Miyaura cross-coupling reaction. Here we report the production of benzophenones by C[sbnd]C cross coupling between a benzoyl-MIDA boronate ester and a multitude of aryl bromide substrates in adequate yields following optimization under ambient conditions outside of a glove box. Under these standard conditions, none of several acyl-MIDA boronate esters (in an alkyl series) serves as a competent coupling partner. The substrate scope is also limited by the finding that the corresponding trifluoroborates of both acyl- and aroyltrifluroborates are not suitable substrates. For reasons of availability and synthetic difficulty in procuring other aroyl-MIDA boronates, this preliminary study examines the reactivity of benzoyl-MIDA boronate with several aryl bromide substrates.
- Lai, Samson,Lin, Wen Xuan,Perrin, David M.,Takaesu, Noah
-
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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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- Nickel-Catalyzed Amination of Aryl Chlorides with Amides
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A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
- Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
-
supporting information
p. 687 - 691
(2021/01/09)
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- Photocatalytic Water-Splitting Coupled with Alkanol Oxidation for Selective N-alkylation Reactions over Carbon Nitride
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Photocatalytic water splitting technology (PWST) enables the direct use of water as appealing “liquid hydrogen source” for transfer hydrogenation reactions. Currently, the development of PWST-based transfer hydrogenations is still in an embryonic stage. Previous reports generally centered on the rational utilization of the in situ generated H-source (electrons) for hydrogenations, in which photogenerated holes were quenched by sacrificial reagents. Herein, the fully-utilization of the liquid H-source and holes during water splitting is presented for photo-reductive N-alkylation of nitro-aromatic compounds. In this integrate system, H-species in situ generated from water splitting were designed for nitroarenes reduction to produce amines, while alkanols were oxidized by holes for cascade alkylating of anilines as well as the generated secondary amines. More than 50 examples achieved with a broad range scope validate the universal applicability of this mild and sustainable coupling approach. The synthetic utility of this protocol was further demonstrated by the synthesis of existing pharmaceuticals via selective N-alkylation of amines. This strategy based on the sustainable water splitting technology highlights a significant and promising route for selective synthesis of valuable N-alkylated fine chemicals and pharmaceuticals from nitroarenes and amines with water and alkanols.
- Xu, Yangsen,Zhang, Zhaofei,Qiu, Chuntian,Chen, Shaoqin,Ling, Xiang,Su, Chenliang
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p. 582 - 589
(2020/12/09)
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- Magnesiation of Aryl Fluorides Catalyzed by a Rhodium-Aluminum Complex
-
We report the magnesiation of aryl fluorides catalyzed by an Al-Rh heterobimetallic complex. We show that the complex is highly reactive to cleave the C-F bonds across the polarized Al-Rh bond under mild conditions. The reaction allows the use of an easy-to-handle magnesium powder to generate a range of arylmagnesium reagents from aryl fluorides, which are conventionally inert to such metalation compared with other aryl halides.
- Fujii, Ikuya,Semba, Kazuhiko,Li, Qiao-Zhi,Sakaki, Shigeyoshi,Nakao, Yoshiaki
-
supporting information
p. 11647 - 11652
(2020/08/06)
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- Silylcarboxylic Acids as Bifunctional Reagents: Application in Palladium-Catalyzed External-CO-Free Carbonylative Cross-Coupling Reactions
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A palladium-catalyzed external-CO-free carbonylative Hiyama-Denmark cross-coupling reaction is presented. The introduction of silylcarboxylic acids as bifunctional reagents (CO and nucleophile source) avoids the need for external gaseous CO and a silylarene coupling partner. The transformation features high functional group tolerance and it is successful with electron-rich, -neutral, and -poor aryl iodides. Stoichiometric studies and control experiments provide insight into the reaction mechanism and support the hypothesized dual role of silylcarboxylic acids. (Figure presented.).
- Li, Xiong,Xu, Jie,Li, Yue,Kramer, S?ren,Skrydstrup, Troels,Lian, Zhong
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p. 4078 - 4083
(2020/07/30)
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- Ruthenium-Catalyzed Dehydrogenation of Alcohols with Carbodiimide via a Hydrogen Transfer Mechanism
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Ruthenium-catalyzed oxidative dehydrogenation of alcohols using carbodiimide as an efficient hydrogen acceptor has been developed. The protocol exhibits wide substrate scope with good to excellent yields. The results of the kinetic analysis indicated that the reaction mechanism includes the hydrogen transfer process and that the addition of carbodiimide is essential for the reaction system, and the resulting amidine also could react as a hydrogen acceptor.
- Sueki, Shunsuke,Matsuyama, Mizuki,Watanabe, Azumi,Kanemaki, Arata,Katakawa, Kazuaki,Anada, Masahiro
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p. 4878 - 4885
(2020/06/02)
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- Scalable Aerobic Oxidation of Alcohols Using Catalytic DDQ/HNO3
-
A selective, practical, and scalable aerobic oxidation of alcohols is described that uses catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HNO3, with molecular oxygen serving as the terminal oxidant. The method was successfully applied to the oxidation of a wide range of benzylic, propargylic, and allylic alcohols, including two natural products, namely, carveol and podophyllotoxin. The conditions are also applicable to the selective oxidative deprotection of p-methoxybenzyl ethers.
- Arseniyadis, Stellios,Clavier, Louis,Copin, Chloé,Fournier, Jean,Giffard, Jean-Fran?ois,Jean, Alexandre,Katsina, Tania,Macedo Portela Da Silva, Nayane,Tamion, Rodolphe
-
supporting information
p. 856 - 860
(2020/07/14)
-
- One-pot, modular approach to functionalized ketones via nucleophilic addition/Buchwald-Hartwig amination strategy
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A general one-pot procedure for the 1,2-addition of organolithium reagents to amides followed by the Buchwald-Hartwig amination with in situ released lithium amides is presented. In this work amides are used as masked ketones, revealed by the addition of organolithium reagents which generates a lithium amide, suitable for subsequent Buchwald-Hartwig coupling in the presence of a palladium catalyst. This methodology allows for rapid, efficient and atom economic synthesis of aminoarylketones in good yields.
- De Jong, Jorn,Heijnen, Dorus,Helbert, Hugo,Feringa, Ben L.
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supporting information
p. 2908 - 2911
(2019/03/17)
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- Catalytic reduction of aryl trialkylammonium salts to aryl silanes and arenes
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A new approach for the reduction of aryl ammonium salts to arenes or aryl silanes using nickel catalysis is reported. This method displays excellent ligand-controlled selectivity based on the N-heterocyclic carbene (NHC) ligand employed. Utilizing a large NHC in non-polar solvents generates aryl silanes, while small NHCs in polar solvents promote reduction to arenes. Several classes of aryl silanes can be accessed from simple aniline building blocks, including those useful for cross-couplings, oxidations, and halogenations. The reaction conditions are mild, functional group tolerant, and provide efficient access to a variety of benzene derivatives.
- Rand, Alexander W.,Montgomery, John
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p. 5338 - 5344
(2019/05/29)
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- MeZnOMe-mediated reaction of aldehydes with Grignard reagents: A glance into nucleophilic addition/Oppenauer oxidation pathway
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A novel organozincate of RMgX ?MeZnOMe ?LiCl type, formed in situ via transmetalation of Grignard reagent RMgBr ?LiCl with MeZnOMe, is shown to be an excellent organometallic species in the nucleophilic addition/Oppenauer oxidation of aldehydes to generate aromatic ketones in high yield. This transformation allows quick access to structurally diverse aryl, heteroaryl, benzyl and alkyl ketones with broad substrate scope and excellent functional group tolerance.
- Fu, Ying,Ma, Xian-Zhen,Shi, Chun-Zhao,Shen, Tong,Du, Zhengyin
-
-
- Generation of Aryl and Heteroaryl Magnesium Reagents in Toluene by Br/Mg or Cl/Mg Exchange
-
The alkylmagnesium alkoxide sBuMgOR?LiOR (R=2-ethylhexyl), which was prepared as a 1.5 m solution in toluene, undergoes very fast Br/Mg exchange with aryl and heteroaryl bromides, producing aryl and heteroaryl magnesium alkoxides (ArMgOR?LiOR) in toluene. These Grignard reagents react with a broad range of electrophiles, including aldehydes, ketones, allyl bromides, acyl chlorides, epoxides, and aziridines, in good yields. Remarkably, the related reagent sBu2Mg?2 LiOR (R=2-ethylhexyl) undergoes Cl/Mg exchange with various electron-rich aryl chlorides in toluene, producing diorganomagnesium species of type Ar2Mg?2 LiOR, which react well with aldehydes and allyl bromides.
- Ziegler, Dorothée S.,Karaghiosoff, Konstantin,Knochel, Paul
-
supporting information
p. 6701 - 6704
(2018/05/05)
-
- Ni/Ti Dual Catalytic Cross-Coupling of Nitriles and Organobromides to Access Ketones
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Herein, we report the development of a dual catalytic approach for the cross-coupling of nitriles with aryl- and aliphatic-bromides. A titanium(III) catalyst is used to activate nitriles enabling their coupling with organobromides through a nickel catalyst. The Ni/Ti system efficiently prepared unsymmetrical ketones with good chemoselectivity and could selectively couple a bromide in the presence of other functionalizable handles.
- Chenniappan, Vinoth Kumar,Silwal, Sajan,Rahaim, Ronald J.
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p. 4539 - 4544
(2018/05/23)
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- Palladium-catalyzed synthesis of diaryl ketones from aldehydes and (hetero)aryl halides via C-H bond activation
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We developed a palladium-catalyzed C-H transformation that enabled the synthesis of ketones from aldehydes and (hetero)aryl halides. The use of picolinamide ligands was key to achieving the transformation. Heteroaryl ketones, as well as diaryl ketones, were synthesized in good to excellent yields, even in gram-scale, using this reaction. Results of density functional theory (DFT) calculations support the C-H bond activation pathway.
- Wakaki, Takayuki,Togo, Takaya,Yoshidome, Daisuke,Kuninobu, Yoichiro,Kanai, Motomu
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p. 3123 - 3128
(2018/04/14)
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- Preparation method of aromatic ketone
-
The invention discloses a preparation method of aromatic ketone. Under the effects of a palladium catalyst and a nitrogen-containing ligand, nitrile compounds and arylsulfonylhydrazide take desulfurization addition reaction in an organic solvent; after the reaction is completed, post treatment is performed to obtain aromatic ketone. The reaction is applicable to aromatic nitrile compounds, and isalso applicable to aliphatic nitrile compounds; the reaction realizes the wide substrate applicability and functional group tolerance; the potential application value is realized in the aspect of aryl-carbonyl building.
- -
-
Paragraph 0046; 0047; 0048; 0050
(2018/09/11)
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- Pd(II)-Catalyzed Denitrogenative and Desulfinative Addition of Arylsulfonyl Hydrazides with Nitriles
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A Pd(II)-catalyzed denitrogenative and desulfinative addition of arylsulfonyl hydrazides with nitriles has been successfully achieved under mild conditions. This transformation is a new method for the addition reaction to nitriles with arylsulfonyl hydrazides as arylating agent, thus providing an alternative synthesis of aryl ketones. The reported addition reaction is tolerant to many common functional groups, and works well in the presence of electron-donating and electron-withdrawing substituents. Notably, the reported denitrogenative and desulfinative addition was also appropriate for alkyl nitriles, making this newly developed transformation attractive.
- Meng, Mengting,Yang, Liangfeng,Cheng, Kai,Qi, Chenze
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p. 3275 - 3284
(2018/03/25)
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- P -Selective (sp2)-C-H functionalization for an acylation/alkylation reaction using organic photoredox catalysis
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p-Selective (sp2)-C-H functionalization of electron rich arenes has been achieved for acylation and alkylation reactions, respectively, with acyl/alkylselenides by organic photoredox catalysis involving an interesting mechanistic pathway.
- Pandey, Ganesh,Tiwari, Sandip Kumar,Singh, Bhawana,Vanka, Kumar,Jain, Shailja
-
supporting information
p. 12337 - 12340
(2017/11/20)
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- Palladium-catalyzed Suzuki-Miyaura coupling of aryl esters
-
The Suzuki-Miyaura coupling is among the most important C-C bond-forming reactions available due to its reliability, chemoselectivity, and diversity. Aryl halides and pseudohalides such as iodides, bromides, and triflates are traditionally used as the electrophilic coupling partner. The expansion of the reaction scope to nontraditional electrophiles is an ongoing challenge to enable an even greater number of useful products to be made from simple starting materials. Herein, we present how an NHC-based Pd catalyst can enable Suzuki-Miyaura coupling where the C(acyl)-0 bond of aryl esters takes on the role of electrophile, allowing the synthesis of various ketone-containing products. This contrasts known reactions of similar esters that provide biaryls via nickel catalysis. The underlying cause of this mechanistic divergence is investigated by DFT calculations, and the robustness of esters compared to more electrophilic acylative coupling partners is analyzed.
- Halima, Taoufik Ben,Zhang, Wanying,Yalaoui, Imane,Hong, Xin,Yang, Yun-Fang,Houk, Kendall N.,Newman, Stephen G.
-
supporting information
p. 1311 - 1318
(2017/05/16)
-
- Synthesis and structural characterization of Pd(II) thiosemicarbazonato complex: Catalytic evaluation in synthesis of diaryl ketones from aryl aldehydes and arylboronic acids
-
A simple route to synthesize triphenylphosphinopalladium(II) thiosemicarbazonato complex has been described. Elemental analysis, spectral (IR, NMR) and single crystal X-ray diffraction techniques were employed for the complete characterization of the complex. The latter was found to be effective catalyst for carbon–carbon cross-coupling reaction of aryl- and heteroarylboronic acids with aromatic and heteroaromatic aldehydes to form the corresponding diaryl ketones. The influence of reaction parameters such as solvent, base, reaction temperature and catalyst loading was also investigated.
- Prabhu, Rupesh Narayana,Ramesh, Rengan
-
supporting information
p. 405 - 409
(2017/01/10)
-
- Efficient and Selective N-Methylation of Nitroarenes under Mild Reaction Conditions
-
Herein, we report a straightforward protocol for the preparation of N,N-dimethylated amines from readily available nitro starting materials using formic acid as a renewable C1 source and silanes as reducing agents. This tandem process is efficiently accomplished in the presence of a cubane-type Mo3PtS4 catalyst. For the preparation of the novel [Mo3Pt(PPh3)S4Cl3(dmen)3]+ (3+) (dmen: N,N′-dimethylethylenediamine) compound we have followed a [3+1] building block strategy starting from the trinuclear [Mo3S4Cl3(dmen)3]+ (1+) and Pt(PPh3)4 (2) complexes. The heterobimetallic 3+ cation preserves the main structural features of its 1+ cluster precursor. Interestingly, this catalytic protocol operates at room temperature with high chemoselectivity when the 3+ catalyst co-exists with its trinuclear 1+ precursor. N-heterocyclic arenes, double bonds, ketones, cyanides and ester functional groups are well retained after N-methylation of the corresponding functionalized nitroarenes. In addition, benzylic-type as well as aliphatic nitro compounds can also be methylated following this protocol.
- Pedrajas, Elena,Sorribes, Iván,Guillamón, Eva,Junge, Kathrin,Beller, Matthias,Llusar, Rosa
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p. 13205 - 13212
(2017/09/12)
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- Coupling of aromatic aldehydes with aryl halides in the presence of nickel catalysts with diazabutadiene ligands
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Nickel catalysts with diazabutadiene ligands promote cross-coupling of benzaldehydes with aryl halides in the presence of zinc as reducing agent, which leads to the corresponding benzhydrols and benzophenones. The benzophenone percentage considerably increases when lithium chloride additive is used.
- Asachenko,Valaeva,Kudakina,Uborsky,Izmer,Kononovich,Voskoboynikov
-
p. 456 - 463
(2017/03/08)
-
- Nickel-catalyzed diaryl ketone synthesis by N-C cleavage: Direct negishi cross-coupling of primary amides by site-selective N,N-Di-boc activation
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A general Negishi acylation of primary amides enabled by a combination of site-selective N,N-di-Boc activation and nickel catalysis is reported for the first time. The reaction is promoted by a bench-stable, inexpensive Ni catalyst. The reaction shows excellent functional group compatibility, affording functionalized diaryl ketones by selective N-C cleavage. Most notably, this protocol represents the first amide cross-coupling by direct metal insertion of simple and readily available primary amides. The overall strategy by N,N-di-Boc activation/metal insertion is suitable for a broad range of coupling protocols via acylmetals. Mechanistic experiments suggest high reactivity of N,N-di-Boc activated 1° amides in direct amide C-N cross-couplings.
- Shi, Shicheng,Szostak, Michal
-
p. 5872 - 5875
(2016/11/29)
-
- Magnesium salt promoted tandem nucleophilic addition-Oppenauer oxidation of aldehydes with organozinc reagents
-
A magnesium salt promoted synthesis of ketones via tandem nucleophilic addition-Oppenauer oxidation of aldehydes using organozinc chemistry was demonstrated. Magnesium salts concomitantly generated via magnesium metal mediated organohalide zincation exhibit high efficacy for nucleophilic addition of organozinc reagents to aromatic aldehydes and thereafter Oppenauer oxidation whereby ketones are formed in high to excellent yields.
- Fu, Ying,Zhao, Xing Ling,Hügel, Hulmet,Huang, Danfeng,Du, Zhengyin,Wang, Kehu,Hu, Yulai
-
supporting information
p. 9720 - 9724
(2016/10/31)
-
- Reversed-polarity synthesis of diaryl ketones through palladium-catalyzed direct arylation of 2-Aryl-1,3-dithianes
-
An umpolung approach to the synthesis of diaryl ketones has been developed based on in situ generation of acyl anion equivalents and their catalytic arylation. This method entails the base-promoted, palladium-catalyzed direct C-H arylation of 2- aryl-1,3-dithianes with aryl bromides. Use of ( SiMe3)2 (M=Li, Na) base results in reversible deprotonation of the weakly acidic dithiane. In the presence of a Pd(NiXantphos)-based catalyst and aryl bromide, cross-coupling of the metallated 2-aryl- 1,3-dithiane takes place under mild conditions (2 h at rt) with yields as high as 96%. The resulting 2,2- diaryl-1,3-dithianes were converted into diaryl ketones by either molecular iodine, N-bromo succinimide (NBS) or Selectfluor in the presence of water. The dithiane arylation/hydrolysis can be performed in a one-pot procedure to yield a variety of diaryl ketones in good to excellent yields. This method is suitable for rapid and large-scale synthesis of diaryl ketones. A one-pot preparation of anti-cholesterol drug fenofibrate (TriCor) has been achieved on 10.0 mmol scale in 86% yield.
- Yucel, Baris,Walsh, Patrick J.
-
p. 3659 - 3667
(2015/01/09)
-
- Reversed-polarity synthesis of Diaryl Ketones through palladium-catalyzed direct Arylation of 2-Aryl-1,3-dithianes
-
An umpolung approach to the synthesis of diaryl ketones has been developed based on in situ generation of acyl anion equivalents and their catalytic arylation. This method entails the base-promoted, palladium-catalyzed direct C-H arylation of 2- aryl-1,3-dithianes with aryl bromides. Use of MNACHTUNGTRENUNG( SiMe3)2 (M=Li, Na) base results in reversible deprotonation of the weakly acidic dithiane. In the presence of a Pd(NiXantphos)-based catalyst and aryl bromide, cross-coupling of the metallated 2-aryl- 1,3-dithiane takes place under mild conditions (2 h at rt) with yields as high as 96%. The resulting 2,2- diaryl-1,3-dithianes were converted into diaryl ketones by either molecular iodine, N-bromo succinimide (NBS) or Selectfluor in the presence of water. The dithiane arylation/hydrolysis can be performed in a one-pot procedure to yield a variety of diaryl ketones in good to excellent yields. This method is suitable for rapid and large-scale synthesis of diaryl ketones. A one-pot preparation of anti-cholesterol drug fenofibrate (TriCor) has been achieved on 10.0 mmol scale in 86% yield.
- Yucel, Baris,Walsh, Patrick J.
-
supporting information
p. 3659 - 3667
(2015/01/09)
-
- Steric and electronic effects influencing β-aryl elimination in the Pd-catalyzed carbon-carbon single bond activation of triarylmethanols
-
An analysis of the palladium-catalyzed activation of carbon-carbon single bonds within triarylmethanols has led to a greater understanding of factors influencing the β-aryl elimination process responsible for C-C bond cleavage. A series of competition reactions were utilized to determine that β-aryl elimination of aryl substituents containing ortho-substitution proceeds with significant preference to unsubstituted phenyl rings. Further experiments indicate that substrates containing either strongly donating or withdrawing substituents are cleaved from triarylmethanols more readily than relatively neutral species.
- Bour, James R.,Green, Jacob C.,Winton, Valerie J.,Johnson, Jeffrey B.
-
p. 1665 - 1669
(2013/03/28)
-
- Reversed-polarity synthesis of diaryl ketones via palladium-catalyzed cross-coupling of acylsilanes
-
Acylsilanes serve as acyl anion equivalents in a palladium-catalyzed cross-coupling reaction with aryl bromides to give unsymmetrical diaryl ketones. Water plays a unique and crucial activating role in these reactions. High-throughput experimentation techniques provided successful reaction conditions initially involving phosphites as ligands. Ultimately, 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane was identified as giving a longer-lived catalyst with higher turnover numbers. Its use, in conjunction with a palladacycle precatalyst, led to optimal reaction rates and yields. Scope and limitations of this novel method are presented along with initial mechanistic insight.
- Schmink, Jason R.,Krska, Shane W.
-
supporting information; experimental part
p. 19574 - 19577
(2012/01/13)
-
- Superelectrophilic chemistry of amino-nitriles and related substrates
-
The superacid-promoted Houben/Hoesch reactions of amino-nitriles and related compounds have been studied. The nitriles form dicationic electrophiles and react with benzene in fair to good yields (12-95%). The intermediate iminium ions may also be reduced to the benzylic amines by NaBH4 or H 2.
- Raja, Erum K.,Klumpp, Douglas A.
-
experimental part
p. 4494 - 4497
(2011/07/08)
-
- Friedel-crafts acylation of arenes with carboxylic acids using polystyrene-supported aluminum triflate
-
Cross-linked polystyrene-supported aluminum triflate (Ps-Al(OTf) 3) has been shown to be a mild, efficient, and chemoselective heterogeneous Lewis acid catalyst for the acylation of aromatic compounds. The catalyst can be easily prepared from cheap starting materials, is stable (as a bench top catalyst) and is reusable.
- Boroujeni, Kaveh Parvanak,Parvanak, Kamran
-
experimental part
p. 155 - 163
(2012/01/02)
-
- Friedel-Crafts acylation of arenes with carboxylic acids using silica gel supported AlCl3
-
Aromatic compounds react smoothly with carboxylic acids in the presence of silica gel supported aluminium trichloride to afford the corresponding ketones with high regioselectivity in high to excellent yields. The catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency. tuebitak.
- Parvanak Boroujeni, Kaveh
-
experimental part
p. 621 - 630
(2010/11/04)
-
- PROCESS FOR PREPARING KETONES FROM ALPHA-OXO CARBOXYLATES AND ARYL BROMIDES
-
A process for preparing ketones of the general formula (III) where R is an optionally substituted carbocyclic aromatic radical having 6 to 24 carbon atoms or an optionally substituted alkyl radical or an optionally substituted heteroaromatic radical having 5 to 24 carbon atoms, andR1 is an optionally substituted carbocyclic aromatic radical having 6 to 24 carbon atoms or an optionally substituted heteroaromatic radical having 5 to 24 carbon atoms, by reacting alpha-oxo carboxylates of the general formula (I) wherein n and m is a number in the range from 1 to 6, M(m+) is a cation, and R has the meaning indicated for formula (III), with aryl bromides of the general formula (II) [in-line-formulae]R1—Br ??(II)[/in-line-formulae] where R1 has the meaning indicated for formula (III), in the presence of two transition metals or compounds thereof as catalyst, is described.
- -
-
Page/Page column 3
(2009/09/08)
-
- Synthesis of ketones from α-oxocarboxylates and aryl bromides by Cu/Pd-catalyzed decarboxylative cross-coupling
-
(Chemical Equation Presented) The power of two metals: A Pd/Cu catalyst system mediates the in situ formation of acyl nucleophiles by decarboxylation of readily accessible and stable salts of α-oxocarboxylic acids and their cross-coupling with aryl or heteroaryl bromides to give ketones. The reaction may be usedin the presence of many functional groups and provides good yields.
- Goossen, Lukas J.,Rudolphi, Felix,Oppel, Christoph,Rodriguez, Nuria
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p. 3043 - 3045
(2008/12/23)
-
- Competitive demethylation and substitution in N,N,N-trimethylanilinium fluorides
-
Fluorination of aromatic compounds by nucleophilic displacement of trimethylanilinium salts by fluoride is a commonly used reaction for radiotracer synthesis. Though the liberated trimethylamine is thought to be an excellent leaving group for this type of SNAr reaction, scattered reports show that amine demethylation (reverse Menschutkin reaction) sometimes dominates over substitution, particularly when relatively electron rich fluoroarenes are the desired targets. Here we provide systematic experimental and theoretical studies of trimethylanilinium demethylation and substitution. Results from these studies highlight the limits of this leaving group in fluoroarene synthesis and have important ramifications for the design of nucleophilic fluorinating agents featuring ammonium cations.
- Sun, Haoran,DiMagno, Stephen G.
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p. 806 - 812
(2008/03/14)
-
- Highly selective catalytic Friedel-Crafts acylation and sulfonylation of activated aromatic compounds using indium metal
-
The Friedel-Crafts acylation of activated benzenes with various aromatic and aliphatic acid chlorides was studied in the presence of indium metal. The reaction was accomplished in high isolated yields under solvent or solvent-less conditions. The method is also applicable for preparing diaryl sulfones from aromatic compounds and aryl sulfonyl chlorides.
- Jang, Doo Ok,Moon, Kyung Soo,Cho, Dae Hyan,Kim, Joong-Gon
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p. 6063 - 6066
(2007/10/03)
-
- Infrared and Nuclear Magnetic Resonance Properties of Benzoyl Derivatives of Five-membered Monoheterocycles and Determination of Aromaticity Indices
-
Benzophenones, 2-benzoylthiophenes, 2-benzoylpyrroles, and 2-benzoylfurans, which have substituents at m- and p-positions of the benzoyl ring were prepared and their ir and nmr spectra were obtained in 0.1 M chloroform-d solution. The chemical shift values of each series were plotted against the Hammett substituent parameters to give good correlation, with the exception of the ortho-Hs and -Cs. The slopes as well as the differences in chemical shift gave sets of meaningful values for the indices of aromaticy.
- Jeon, Kyu Ok,Jun, Jung Ho,Yu, Ji Sook,Lee, Chang Kiu
-
p. 763 - 771
(2007/10/03)
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- A highly selective photooxidation approach using O2 in water catalyzed by iron(II) bipyridine complex supported on NaY zeolite
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A new photocatalytic system involving iron(II) bipyridine supported on NaY zeolite (FeBY) shows excellent reactivity and selectivity in the oxidation of organic compounds. This approach allows highly controlled oxidation reaction to occur but avoids undesirable mineralization into CO2 and H 2O.
- Li, Jing,Ma, Wanhong,Huang, Yingping,Cheng, Mingming,Zhao, Jincai,Yu, Jimmy C.
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p. 2214 - 2215
(2007/10/03)
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- Photo-Fenton degradation of malachite green catalyzed by aromatic compounds under visible light irradiation
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The photo-Fenton degradation of malachite green (MG) catalyzed by aromatic derivatives under visible light irradiation was examined. Aromatic derivatives exhibit significant catalytic action in the photo-Fenton reaction. The degradation rates of MG with various kinds of aromatic derivatives obey the following order: hydroquinone > salicylic acid > quinone > carboxylic aromatic derivatives > amido aromatic derivatives. GC-MS detection of the products formed in the MG Fenton degradation in the presence of aromatic derivatives shows that the addition of the latter does not change the MG degradation pathways, although it greatly alters the reaction rate. The MG degradation mainly involves two different pathways: cleavage with a [MG-OH]· transition intermediate and N-demethylation.
- Chen, Feng,He, Jianjun,Zhao, Jincai,Yu, Jimmy C.
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p. 336 - 341
(2007/10/03)
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- Unusual aminations with tetramethylguanidine
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Heating activated halobenzenes with 1,1,3,3-tetramethylguanidine affords mixtures of dimethylaminobenzenes and 2-aryl-1,1,3,3-tetramethylguanidines.
- Gabbutt, Christopher D.,Heron, B. Mark,McCreary, Janice M.,Thomas, David A.
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- Palladium-Catalyzed Carbonylative Cross-Coupling Reaction of Arylboronic Acids with Aryl Electrophiles: Synthesis of Biaryl Ketones
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The carbonylative cross-coupling reaction of arylboronic acids with aryl electrophiles (ArI, ArBr, and ArOTf) to yield unsymmetrical biaryl ketones was carried out in anisole at 80°C in the presence of a palladium catalyst and a base. The reaction selectively proceeded under an atmospheric pressure of carbon monoxide when PdCl2(PPh3)2 (3 mol %)/K2CO3 (3 equiv) were used for aryl iodides and PdCl2(dppf) (3 mol %)/K2CO3 (3 equiv)/KI (3 equiv) for the bromides or the triflates. The carbonylation of arylboronic acids with benzyl halides gave aryl benzyl ketones.
- Ishiyama, Tatsuo,Kizaki, Hiroe,Hayashi, Takahiro,Suzuki, Akira,Miyaura, Norio
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p. 4726 - 4731
(2007/10/03)
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- Photochemical Electron Transfer Initiated Oxidative Fragmentation of Aminopinacols. Factors Governing Reaction Rates and Quantum Efficiencies of C-C Bond Cleavage
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The fragmentation reactions of the cation radicals of a series of remote diamine-substituted pinacols have been investigated.The cation radicals were generated upon photooxidation with excited 2,6,9,10-tetracyanoanthracence in acetonitrile.The products are consistent with cleavage of the central C-C bond.The rate constants for fragmentation were determined both from steady-state quantum yield studies and from time-resolved measurements.In general, the rate constants for fragmentation increase with increasing stability of the radical and cation products.However, the results of temperature dependence studies clearly demonstrate that conformational effects play an important role in the transition state.In some cases, these conformational effects can result in changes in the reactivity order expected from purely thermodynamic considerations.
- Gan, Hong,Leinhos, Uwe,Gould, Ian R.,Whitten, David G.
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p. 3566 - 3573
(2007/10/02)
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- Synthesis of unsymmetrical biaryl ketones via palladium-catalyzed carbonylative cross-coupling reaction of arylboronic acids with iodoarenes
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The cross-coupling reaction between arylboronic acids, carbon monoxide (1 atm), and aryl iodides in the presence of palladium catalyst and base provided unsymmetrical biaryl ketones in high yields. The choice of a suitable base and solvent was essential to achieve selective formation of the unsymmetrical biaryl ketone without a biaryl by-product.
- Ishiyama,Kizaki,Miyaura,Suzuki
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p. 7595 - 7598
(2007/10/02)
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- Direct Formation and Reaction of Thienyl-Based Organocopper Reagents
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The preparation of a highly reactive zerovalent copper complex by the direct reduction of lithium (2-thienylcyano)cuprate with preformed lithium naphthalenide is described.This active copper species oxidatively adds to carbon-halogen bonds to form organocopper reagents.The ability to directly form the organocopper reagent from organic halides and active copper allows for the incorporation of a wide variety of functionalities to be present in the organic halides and the organocopper reagents.Significantly, this formulation of active copper was able to oxidatively add to allyl chlorides and acetates at low temperatures to allow the direct formation of allylic organocopper reagents without Wurtz-type homocoupling.These functionalized organocopper compounds are able to undergo a variety of reactions, such as cross-coupling with acid chlorides, 1,4-conjugate addition with α,β-unsaturated carbonyl compounds, and intermolecular and intramolecular epoxide-opening reactions.Subsequently, this copper species avoids the use of phosphine ligands affording the product isolation much more convenient than with phosphine-based organocopper reagents.
- Rieke, Reuben D.,Klein, Walter R.,Wu, Tse-Chong
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p. 2492 - 2500
(2007/10/02)
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- Photocurable compositions and methods
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Photocurable compositions which comprise a light sensitive composition in combination with at least one initiator therefor are improved by the use of dibenzoyl benzene as the photoinitiator. In a preferred combination, para-dibenzoyl benzene is employed in combination with para-di(4--dimethylaminobenzoyl) benzene. The photocurable compositions can be used for various purposes including preparation of lithographic printing plates.
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- Photoinitiator
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Photocurable compositions which comprise a light sensitive composition in combination with at least one initiator therefor are improved by the use of para--di(4-dimethylaminobenzoyl) benzene as the photoinitiator. The photocurable compositions can be used for various purposes including preparation of lithographic printing plates.
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- DIRECT FORMATION AND REACTION OF FUNCTIONALIZED THIENYL-BASED ORGANOCOPPER REAGENTS
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Highly reactive copper solutions have been prepared by the direct reduction of lithium 2-thienylcyanocuprate.Product isolation was much easier using the thienyl-based organocopper reagents as opposed to phosphine-based organocopper reagents
- Rieke, Reuben D.,Wu, Tse-Chong,Stinn, Dean E.,Wehmeyer, Richard M.
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p. 1833 - 1840
(2007/10/02)
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- 1,3-Dithienium and 1,3-Dithiolenium Salts, VI. - N,N-Disubstituted 4-Aminobenzophenones from 1,3-Dithian- and 1,3-Dithiolan-2-ylium Tetrafluoroborates, respectively
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The 1,3-dithienium- and 1,3-dithiolenium tetrafluoroborates 3 (n =3, 2), respectively, react in good yields with the N,N-dialkylarylamines 4 to give the 2,2-disubstituted cyclic dithio acetals 5, which can be converted after dethioacetalization with HgCl2/HgO into the ketones 7.
- Stahl, Ingfried
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p. 135 - 140
(2007/10/02)
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- SELECTIVE CARBOPHILIC ADDITION OF ORGANOLITHIUMS TO THIOAMIDES. A NOVEL SYNTHESIS OF UNSYMMETRICAL KETONES AND α-ALKYLATED AMINES
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Thioamides, readily available from aldehydes, sulfur and secondary amines, can be converted to unsymmetrical ketones by the carbophilic addition of organolithiums to the thiocarbonyl group.Reduction of the intermediates with lithium aluminium hydride gives α-alkylated or α-arylated amines.
- Tominaga, Yoshinori,Kohra, Shinya,Hosomi, Akira
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p. 1529 - 1532
(2007/10/02)
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- 2-Substituted 1,3-Benzoxathiolium Tetrafluoroborates as Efficient Acylating Agents for N,N-Dialkylarylamines
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2-Substituted 1,3-benzoxathiolium tetrafluoroborates were used as efficient masked acylating agents for N,N-dialkylarylamines in a two-step reaction.In most of the cases intermediate 2,2-disubstituted 1,3-benzoxathioles were obtained in high yields (about 90percent) and their hydrolysis afforded the corresponding ketones in almost quantitative yields.The new procedure offers the following advantages: (1) the reaction conditions are mild; (2) the acylation proceeds selectively at the para-position as referred to the dialkylamino group; (3) the introduction of a tertiary group is easily accomplished.
- Cadamuro, Silvano,Degani, Iacopo,Fochi, Rita,Gatti, Antonella,Regondi, Valeria
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p. 544 - 547
(2007/10/02)
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