- 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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- 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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- 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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supporting information
p. 10896 - 10908
(2021/08/17)
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- N-Acylcarbazoles and N-Acylindoles: Electronically Activated Amides for N-C(O) Cross-Coupling by Nlpto Ar Conjugation Switch
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The development of new amide precursors for selective, catalytic activation of carbon-nitrogen bonds in amides is a fundamental objective of this emerging reactivity manifold. We report the palladium-catalyzed Suzuki-Miyaura cross-coupling of N-acylcarbazoles and N-acylindoles with arylboronic acids by a highly selective N-C(O) cleavage. The key amide bond ground-state destabilization stems from Nlp to Ar conjugation and enables us for the first time to achieve reactivity similar to that for N-acylsulfonamide and N-acylcarbamate activation in simple anilides.
- Buchspies, Jonathan,Rahman, Md. Mahbubur,Szostak, Roman,Szostak, Michal
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supporting information
p. 4703 - 4709
(2020/06/17)
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- Rhodium-Catalyzed Remote Isomerization of Alkenyl Alcohols to Ketones
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We develop herein an efficient rhodium-catalyzed remote isomerization of aromatic and aliphatic alkenyl alcohols into ketones. This catalytic process, with a commercially available catalyst and ligand ([RhCl(cod)]2 and Xantphos), features high efficiency, low catalyst loading, good functional group tolerance, a broad substrate scope, and no (sub)stoichiometric additive. Preliminary mechanistic studies suggest that this transformation involves an iterative dissociative β-hydride elimination-migration insertion process.
- Dong, Wenke,Yang, Hongxuan,Yang, Wen,Zhao, Wanxiang
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supporting information
(2020/02/28)
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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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- Iridium-Catalyzed Alkylation of Secondary Alcohols with Primary Alcohols: A Route to Access Branched Ketones and Alcohols
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Under borrowing hydrogen conditions, NHC-iridium(I) catalyzed the direct or one-pot sequential synthesis of α,α-disubstituted ketones via the alkylation of secondary alcohols with primary alcohols is reported. Notably, the present approach provides a new method for the facile synthesis of α,α-disubstituted ketones and featured with several characteristics, including a broad substrate scope, using easy-to-handle alcohols as starting materials, and performing the reactions under aerobic conditions. Moreover, the selective one-pot formation of β,β-disubstituted alcohols was achieved by the addition of an external hydrogen source to the reaction mixture.
- Gen?, Serta?,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
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p. 9139 - 9152
(2020/08/14)
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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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- 2-Methyltetrahydrofuran (2-MeTHF): A Green Solvent for Pd?NHC-Catalyzed Amide and Ester Suzuki-Miyaura Cross-Coupling by N?C/O?C Cleavage
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The palladium-NHC-catalyzed (NHC=N-heterocyclic carbene) Suzuki-Miyaura cross-coupling of amides and esters via highly chemoselective N?C(O) and O?C(O) cleavage with aryl boronic acids using green, sustainable and eco-friendly 2-methyltetrahydrofuran (2-MeTHF) is reported. A variety of amides and aryl esters were coupled with aryl boronic acids in high to excellent yields. This method employs commercially-available, air- and moisture-stable Pd(II) ?NHC precatalysts. Crucially, the use of 2-MeTHF leads to the highest TON reported to date in amide N?C(O) bond cross-coupling. This operationally-simple protocol was utilized in the synthesis a bioactive ketone intermediate, emphasizing the potential of 2-MeTHF as a green solvent in unconventional amide bond disconnection. Given the tremendous importance of amide bond cross-coupling strategies and the drive to maintain full sustainability in cross-coupling processes, we expect that the synthetic method will be of broad interest.
- Lei, Peng,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
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supporting information
p. 5654 - 5660
(2019/11/16)
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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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- 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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p. 769 - 779
(2019/01/24)
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- Switchable Chemoselective Transfer Hydrogenations of Unsaturated Carbonyls Using Copper(I) N-Donor Thiolate Clusters
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Unsaturated alcohols and saturated carbonyls are important chemical, pharmaceutical, and biochemical intermediates. We herein report an efficient transfer hydrogenation protocol in which conversion of unsaturated carbonyl compounds to either unsaturated alcohols or saturated carbonyls was catalyzed by Cu(I) N-donor thiolate clusters along with changing hydrogen source (isopropanol or butanol) and base (NaOH or K2CO3). Mechanistic studies supported by DFT transition state modeling indicate that such a chemoselectivity can be explained by the relative concentrations of Cu(I) monohydride and protonated Cu(I) hydride complexes in each catalytic system.
- Zhang, Meng-Juan,Tan, Da-Wei,Li, Hong-Xi,Young, David James,Wang, Hui-Fang,Li, Hai-Yan,Lang, Jian-Ping
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p. 1204 - 1215
(2018/02/09)
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- Pd-PEPPSI: Water-Assisted Suzuki?Miyaura Cross-Coupling of Aryl Esters at Room Temperature using a Practical Palladium-NHC (NHC=N-Heterocyclic Carbene) Precatalyst
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A Pd-PEPPSI-catalyzed (Pd=Palladium, PEPPSI=pyridine-enhanced precatalyst preparation stabilization and initiation) Suzuki-Miyaura cross-coupling of aryl esters via selective C?O cleavage at room temperature is reported. The developed catalyst system displays broad substrate scope with respect to both components under practical ambient reaction conditions using readily-available, cheap, modular, air- and moisture-stable Pd-NHC precatalyst (NHC=N-heterocyclic carbene). The use of water proved crucial for achieving high reactivity in this coupling. The catalyst system represents the mildest conditions for the Suzuki?Miyaura cross-coupling of aryl esters reported to date. The protocol also allowed for achieving TON >1,000 (TON=turnover number) in the Suzuki?Miyaura ester coupling for the first time. (Figure presented.).
- Li, Guangchen,Shi, Shicheng,Lei, Peng,Szostak, Michal
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supporting information
p. 1538 - 1543
(2018/03/01)
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- Iridium(I)-Catalyzed Alkylation Reactions to Form α-Alkylated Ketones
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A highly effective and green procedure for the formation of α-alkylated ketones has been disclosed via the reaction of primary alcohols with secondary alcohols and ketones by using [IrCl(COD)(NHC)] complexes as a catalyst. Various α-alkylated ketones were obtained in high yields from the alkylation of alcohol with alcohol and ketone with alcohol through a borrowing hydrogen reaction by using 0.05-0.5 mol % iridium(I) and a catalytic amount of KOH (5-10 mol %) as the base under air atmosphere and within very short reaction times.
- Gen?, Serta?,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Süleyman,Gülcemal, Derya
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p. 2875 - 2881
(2018/03/09)
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- Solvent-free direct α-alkylation of ketones by alcohols catalyzed by nickel supported on silica-alumina
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The α-alkylation of acetophenone with benzyl alcohol through borrowing hydrogen has been studied using nickel catalysis. Ni/SiO2-Al2O3 was found to be the best catalyst for this transformation and the corresponding alkylated acetophenone was obtained with 93% isolated yield. Following the objectives of clean and sustainable chemistry, the reaction occurs under solvent-free conditions and requires only a catalytic amount of base. This protocol was next applied to a wide range of ketones and alcohols and the desired products were isolated with 18-86% yields (26 examples). The recovery and recyclability of the nickel catalyst was also investigated and it was found to be active over 5 runs without significant loss of activity. Surprisingly, the active catalyst appears to include an amorphous nickel hydroxide layer.
- Charvieux, Aubin,Giorgi, Javier B.,Duguet, Nicolas,Métay, Estelle
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supporting information
p. 4210 - 4216
(2018/10/02)
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- Suzuki-Miyaura cross-coupling of amides and esters at room temperature: Correlation with barriers to rotation around C-N and C-O bonds
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The Suzuki-Miyaura cross-coupling has been widely recognized as one of the most important methods for the construction of C-C bonds. However, in contrast to traditional aryl halide or pseudohalide electrophiles, coupling reactions with unactivated C-N and C-O electrophiles have proven significantly more challenging. Here we report the first general palladium-catalyzed Suzuki-Miyaura cross-coupling of both common amides and aryl esters through the selective cleavage of the C-N and C-O bonds under exceedingly mild conditions. Notably, for the first time we demonstrate selective C(acyl)-N and C(acyl)-O cleavage/cross-coupling under the same reaction conditions. The reaction uses a commercially available, bench-stable and operationally-convenient (η3-1-t-Bu-indenyl)Pd(IPr)(Cl) precatalyst. Furthermore, we demonstrate that the reactivity of generic amides and aryl esters can be correlated with barriers to isomerization around the C(acyl)-X (X = N, O) bond, thus providing a blueprint for the development of a broad range of novel coupling reactions of ester and amide electrophiles by the selective activation of C-O and C-N bonds.
- Lei, Peng,Meng, Guangrong,Shi, Shicheng,Ling, Yun,An, Jie,Szostak, Roman,Szostak, Michal
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p. 6525 - 6530
(2017/08/29)
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- Pd-PEPPSI: A General Pd-NHC Precatalyst for Suzuki-Miyaura Cross-Coupling of Esters by C-O Cleavage
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The Suzuki-Miyaura cross-coupling of aryl esters by selective C-O bond cleavage represents a powerful methodology in organic synthesis. Here, we report that versatile, easily prepared, well-defined Pd-PEPPSI type precatalysts serve as highly reactive catalysts for the direct Suzuki-Miyaura cross-coupling of esters. Sterically and electronically diverse aryl esters couple with arylboronic acids in good to excellent yields using a single, operationally simple protocol. Kinetic studies demonstrate that the cross-coupling of aryl esters proceeds with rates similar to the cross-coupling of amides. This study strongly supports the use of well-defined Pd(II)-NHC precatalysts bearing pyridine throw-away ligands for the selective C(acyl) cleavage of bench-stable carboxylic acid derivatives. Considering the modular scaffold of Pd-NHC precatalysts, we envision that the method will be of general interest for the development of new catalysts for C-O cleavage reactions.
- Shi, Shicheng,Lei, Peng,Szostak, Michal
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supporting information
p. 3784 - 3789
(2017/10/13)
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- Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling of N-Mesylamides by N-C Cleavage: Electronic Effect of the Mesyl Group
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A general Pd-catalyzed Suzuki-Miyaura cross-coupling of N-mesylamides with arylboronic acids by selective N-C cleavage has been developed. The presented results represent the first example of a transition-metal-catalyzed cross-coupling of amides activated by an atom-economic, cheap, and benign mesyl group. The reaction delivers arylated products featuring a range of useful functional groups by chemoselective cleavage of the amide N-C bond with high efficiency. Both the scope and the origin of high selectivity are discussed. A beneficial effect of the N-mesyl substituent on the bond activation in acyclic amides is presented.
- Liu, Chengwei,Liu, Yongmei,Liu, Ruzhang,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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supporting information
p. 1434 - 1437
(2017/03/23)
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- Pd-PEPPSI: Pd-NHC Precatalyst for Suzuki-Miyaura Cross-Coupling Reactions of Amides
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Pd-PEPPSI-IPr serves as a highly reactive precatalyst in the direct Suzuki-Miyaura cross-coupling of amides. An array of amides can be cross-coupled with a range of arylboronic acids in very good yields using a single, operationally simple protocol. The studies described represent the first use of versatile PEPPSI type of Pd-NHC complexes as catalysts for the cross-coupling of amides by N-C bond activation. The method is user-friendly, since it employs a commercially available, air- and moisture-stable Pd-PEPPSI-IPr complex. Pd-PEPPSI-IPr provides a significant improvement over all current Pd/phosphane catalysts for amide N-C bond activation. Mechanistic studies provide insight into the reaction rates of Pd-NHC-catalyzed cross-coupling of different amides, with Pd-PEPPSI-IPr being particularly effective for the cross-coupling of N-Boc carbamates under the developed conditions.
- Lei, Peng,Meng, Guangrong,Ling, Yun,An, Jie,Szostak, Michal
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p. 6638 - 6646
(2017/07/15)
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- Acceptorless dehydrogenation and dehydrogenative coupling of alcohols catalysed by protic NHC ruthenium complexes
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A new family of protic NHC Ru complexes ligated with a phosphine-tethered imidazole moiety were prepared, which can act as excellent catalysts for acceptorless dehydrogenation of secondary alcohols and dehydrogenative coupling of primary and secondary alcohols, thus leading to the formation of a variety of carbonyl compounds with release of H2.
- Chang, Weihong,Gong, Xue,Wang, Shuizhong,Xiao, Ling-Ping,Song, Guoyong
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supporting information
p. 3466 - 3471
(2017/04/26)
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- Use of a Cyclometalated Iridium(III) Complex Containing a N∧C∧N-Coordinating Terdentate Ligand as a Catalyst for the α-Alkylation of Ketones and N-Alkylation of Amines with Alcohols
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A cyclometalated iridium(III) complex containing a N∧C∧N-coordinating terdentate ligand [Ir(dpyx-N,C,N)Cl(μ-Cl)]2 was found to be a general and highly effective catalyst for the α-alkylation of ketones and N-alkylation of amines with alcohols. In the presence of catalyst (1 mol % Ir) and base (0.2-0.5 equiv), a variety of desirable products were obtained in good yields under an air atmosphere. Notably, this research exhibited the new potential of Ir(III) complexes bearing non-Cp? ligand and will facilitate the progress of the hydrogen autotransfer process.
- Liu, Pengcheng,Liang, Ran,Lu, Lei,Yu, Zhentao,Li, Feng
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p. 1943 - 1950
(2017/02/26)
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- Cobalt-Catalyzed α-Alkylation of Ketones with Primary Alcohols
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An ionic cobalt-PNP complex is developed for the efficient α-alkylation of ketones with primary alcohols for the first time. A broad range of ketone and alcohol substrates were employed, leading to the isolation of alkylated ketones with yields up to 98%. The method was successfully applied to the greener synthesis of quinoline derivatives while using 2-aminobenzyl alcohol as an alkylating reagent.
- Zhang, Guoqi,Wu, Jing,Zeng, Haisu,Zhang, Shu,Yin, Zhiwei,Zheng, Shengping
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supporting information
p. 1080 - 1083
(2017/03/14)
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- Ruthenium phosphine-pyridone catalyzed cross-coupling of alcohols to form α-alkylated ketones
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An efficient and green route to access diverse functionalized ketones via dehydrogenative-dehydrative cross-coupling of primary and secondary alcohols is demonstrated. Selective and tunable formation of ketones or alcohols is catalyzed by a recently developed proton responsive ruthenium phosphine-pyridone complex. Light alcohols such as ethanol could be used as alkylating agents in this methodology. Moreover, selective tandem double alkylation of isopropanol is achieved by sequential addition of different alcohols.
- Sahoo, Apurba R.,Lalitha, Gummidi,Murugesh,Bruneau, Christian,Sharma, Gangavaram V.M.,Suresh, Surisetti,Achard, Mathieu
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p. 10727 - 10731
(2018/05/31)
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- N-acylsaccharins: Stable electrophilic amide-based acyl transfer reagents in Pd-catalyzed Suzuki-Miyaura coupling via N-C cleavage
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The development of efficient catalytic methods for N-C bond cleavage in amides remains an important synthetic challenge. The first Pd-catalyzed Suzuki-Miyaura cross-coupling of N-acylsaccharins with boronic acids by selective N-C bond activation is reported. The reaction enables preparation of a variety of functionalized diaryl and alkyl-aryl ketones with broad functional group tolerance and in good to excellent yields. Of general interest, N-acylsaccharins serve as new, highly reactive, bench-stable, economical, amide-based, electrophilic acyl transfer reagents via acyl-metal intermediates. Mechanistic studies strongly support the amide N-C(O) bond twist as the enabling feature of N-acylsaccharins in the N-C bond cleavage.
- Liu, Chengwei,Meng, Guangrong,Liu, Yongmei,Liu, Ruzhang,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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supporting information
p. 4194 - 4197
(2016/09/09)
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- A method for synthesis of α-alkyl ketone
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The invention discloses a method for synthesizing alpha-alkyl ketone. The method comprises the following steps: adding alkyne, [(IPr)AuCl], AgOTf, 1,4-dioxane and water in a reaction container, performing microwave reaction on a reaction mixture for 1h at 120 DEG C and cooling to room temperature; further adding [Cp*IrCl2]2, alkali and alcohol into the reaction mixture, performing microwave reaction on the reaction mixture for 2h at 130 DEG C and cooling to room temperature; filtering, performing rotary evaporation to remove a solvent, and then separating by a column to obtain a target compound. The method disclosed by the invention is started from chemical raw materials which are easy to obtain, namely alkyne, water and alcohol, alpha-alkyl ketone is obtained under the participation of gold and iridium catalysts, and the reaction only generates water as a byproduct. Therefore, the reaction is in line with the requirements of green chemistry and has broad development prospects.
- -
-
Paragraph 0099; 0100; 0101; 0102
(2016/11/28)
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- Palladium-catalyzed Suzuki-Miyaura coupling of amides by carbon-nitrogen cleavage: General strategy for amide N-C bond activation
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The first palladium-catalyzed Suzuki-Miyaura cross-coupling of amides with boronic acids for the synthesis of ketones by sterically-controlled N-C bond activation is reported. The transformation is characterized by operational simplicity using bench-stable, commercial reagents and catalysts, and a broad substrate scope, including substrates with electron-donating and withdrawing groups on both coupling partners, steric-hindrance, heterocycles, halides, esters and ketones. The scope and limitations are presented in the synthesis of >60 functionalized ketones. Mechanistic studies provide insight into the catalytic cycle of the cross-coupling, including the first experimental evidence for Pd insertion into the amide N-C bond. The synthetic utility is showcased by a gram-scale cross-coupling and cross-coupling at room temperature. Most importantly, this process provides a blueprint for the development of a plethora of metal catalyzed reactions of typically inert amide bonds via acyl-metal intermediates. A unified strategy for amide bond activation to enable metal insertion into N-C amide bond is outlined (Scheme 1).
- Meng, Guangrong,Szostak, Michal
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supporting information
p. 5690 - 5707
(2016/07/06)
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- Chemoselective Ketone Synthesis by the Addition of Organometallics to N-Acylazetidines
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A general and highly chemoselective method for the synthesis of ketones by the addition of organometallics to N-acylazetidines via stable tetrahedral intermediates is reported for the first time. The transformation is characterized by its wide substrate scope and exquisite selectivity for the ketone products even when a large excess of nucleophilic reagents is used. Even of broader interest is the use of N-acylazetidines as bench-stable, readily available amide acylating reagents, in which the reactivity is controlled by amide pyramidalization and strain of the four-membered ring to afford synthetically valuable building blocks.
- Liu, Chengwei,Achtenhagen, Marcel,Szostak, Michal
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supporting information
p. 2375 - 2378
(2016/06/09)
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- Bifunctional Ru(II) complex catalysed carbon-carbon bond formation: an eco-friendly hydrogen borrowing strategy
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The atom economical borrowing hydrogen methodology enables the use of alcohols as alkylating agents for selective C-C bond formation. A bifunctional 2-(2-pyridyl-2-ol)-1,10-phenanthroline (phenpy-OH) based Ru(ii) complex (2) was found to be a highly efficient catalyst for the one-pot β-alkylation of secondary alcohols with primary alcohols and double alkylation of cyclopentanol with different primary alcohols. Exploiting the metal-ligand cooperativity in complex 2, several aromatic, aliphatic and heteroatom substituted alcohols were selectively cross-coupled in high yields using significantly low catalyst loading (0.1 mol%). An outer-sphere mechanism is proposed for this system as exogenous PPh3 has no significant effect on the rate of the reaction. Notably, this is a rare one-pot strategy for β-alkylation of secondary alcohols using a bifunctional Ru(ii)-complex. Moreover, this atom-economical methodology displayed the highest cumulative turn over frequency (TOF) among all the reported transition metal complexes in cross coupling of alcohols.
- Chakrabarti, Kaushik,Paul, Bhaskar,Maji, Milan,Roy, Bivas Chandra,Shee, Sujan,Kundu, Sabuj
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p. 10988 - 10997
(2016/12/06)
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- Palladium catalyzed decarboxylative acylation of arylboronic acid with ethyl cyanoacetate as a new acylating agent: Synthesis of alkyl aryl ketones
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Palladium catalyzed acylation of arylboronic acid containing various functional groups was performed efficiently by ethyl cyanoacetate/substituted ethyl cyanoacetate as the acylating agent in aqueous triflic acid medium. The alkyl aryl ketones were obtained in good to excellent yields, first by addition of arylboronic acid to the nitrile group of ethyl cyanoacetate and their derivatives, followed by in situ decarboxylation of the resulting β-ketoester.
- Yousuf, Md,Das, Tuluma,Adhikari, Susanta
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p. 8763 - 8770
(2015/11/10)
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- Synthesis of a-Alkylated Ketones via Tandem Acceptorless Dehydrogenation/a-Alkylation from Secondary and Primary Alcohols Catalyzed by Metal-Ligand Bifunctional Iridium Complex [CpIr(2,2′-bpyO)(H2O)]
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A new strategy for the synthesis of α-alkylated ketones via tandem acceptorless dehydrogenation/α-alkylation from secondary and primary alcohols was proposed and accomplished. In the presence of metal-ligand bifunctional iridium complex [CpIr(2,2′-bpyO)(H2O)], various desirable products were obtained in high yields. Compared with previous methods for the direct dehydrogenative coupling of secondary alcohols with primary alcohols to α-alkylated ketones, this protocol has obvious advantages including complete selectivity for α-alkylated ketones and more environmentally benign conditions. Notably, the study also exhibited the potential to develop tandem reactions catalyzed using a metal-ligand bifunctional iridium complex.
- Wang, Rongzhou,Ma, Juan,Li, Feng
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p. 10769 - 10776
(2015/11/18)
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- An efficient heterogenized palladium catalyst for N-alkylation of amines and α-alkylation of ketones using alcohols
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A silica supported palladium-NiXantphos complex is reported as an efficient and a high turnover heterogeneous catalyst for the N-alkylation of amines and the α-alkylation of ketones using readily available alcohols under neat conditions at 120-140 °C following hydrogen borrowing strategy. The catalyst is easily separable and offers negligible amount of palladium leaching (0.01 ppm). A high turnover number of about 46000 for the N-alkylation of amines and 4400 for the α-alkylation of ketones were achieved in the respective single batch reactions. The catalyst is recyclable up to four times without appreciable change in catalytic performance.
- Dang, Tuan Thanh,Shan, Siah Pei,Ramalingam, Balamurugan,Seayad, Abdul Majeed
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p. 42399 - 42406
(2015/05/20)
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- Iodine promoted α-hydroxylation of ketones
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A novel method for α-hydroxylation of ketones using substoichiometric amount of iodine under metal-free conditions is described. This method has been successfully employed in synthesizing a variety of heterocyclic compounds, which are useful precursors. α-Hydroxylation of diketones and triketones are illustrated. This strategy provides a novel, efficient, mild and inexpensive method for α-hydroxylation of aryl ketones using a sub-stoichiometric amount of molecular iodine.
- Siddaraju, Yogesh,Prabhu, Kandikere Ramaiah
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supporting information
p. 6749 - 6753
(2015/06/25)
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- A chemoselective α-aminoxylation of aryl ketones: a cross dehydrogenative coupling reaction catalysed by Bu4NI
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Tetrabutyl ammonium iodide (TBAI) catalyzed α-aminoxylation of ketones using aq. TBHP as an oxidant has been accomplished. We have shown that the CDC (cross dehydrogenative coupling) reactions of ketones with N-hydroxyimidates such as N-hydroxysuccinimide (NHSI), N-hydroxyphthalimide (NHPI), N-hydroxybenzotriazole (HOBt) and 1-hydroxy-7-azabenzotriazole (HOAt) lead to the corresponding oxygenated products in good to moderate yields. The application of this method has been demonstrated by transforming a few coupled products into synthetically useful intermediates and products.
- Siddaraju, Yogesh,Prabhu, Kandikere Ramaiah
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supporting information
p. 11651 - 11656
(2015/12/08)
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- Synthesis, structures of benzoxazolyl iridium(III) complexes, and applications on C-C and C-N bond formation reactions under solvent-free conditions: Catalytic activity enhanced by noncoordinating anion without silver effect
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Several new bisbenzoxazolyl iridium(III) complexes have been synthesized and characterized through X-ray crystallography. These complexes exhibit excellent catalytic activity in C-C and C-N bond formation reactions from the alkylation of amine with amine, amine with alcohol, ketone with alcohol, and alcohol with alcohol through a borrowing hydrogen reaction. Moreover, these iridium(III) complexes are effective catalysts for the alkylation of amine with alcohol and ketone with alcohol under solvent-free conditions. The catalytic activity of these complexes is greatly enhanced by noncoordinating, while the experiments have excluded the possibility of a "silver effect" (bimetallic catalysis or silver-assisted metal catalysis) from the experiments.
- Wang, Dawei,Zhao, Keyan,Xu, Chongying,Miao, Hongyan,Ding, Yuqiang
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p. 3910 - 3918
(2014/12/12)
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- α-alkylation of ketones by trialkylamines under heterogeneous Pd/C catalysis
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Ketones are regioselectively α-alkylated with trialkylamines in toluene at 120 °C in the presence of Pd/C.
- Yoon, Il Chul,Kim, Tae Gyun,Cho, Chan Sik
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p. 1890 - 1892
(2014/05/06)
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- Clean borrowing hydrogen methodology using hydrotalcite supported copper catalyst
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The catalytic activity of Mg-Al hydrotalcite supported copper catalyst was investigated for clean CC and CN bond forming reactions using alcohols as alkylating agent via borrowing hydrogen methodology. The catalyst showed excellent conversion of ketone and amine substrates (71-99%) to alkylated products with high selectivity in alkylation reactions.
- Dixit, Manish,Mishra, Manish,Joshi, Pradyuman A.,Shah, Dinesh O.
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- Lithium tert-butoxide mediated α-alkylation of ketones with primary alcohols under transition-metal-free conditions
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LiOtBu was found to efficiently promote the α-alkylation reaction of ketones with primary alcohols, without the addition of any transition metal catalyst.
- Liang, Yu-Feng,Zhou, Xin-Feng,Tang, Shi-Ya,Huang, Yao-Bing,Feng, Yi-Si,Xu, Hua-Jian
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p. 7739 - 7742
(2013/06/27)
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- Osmium catalyst for the borrowing hydrogen methodology: α-alkylation of arylacetonitriles and methyl ketones
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Complex [Os(η6-p-cymene)(OH)(IPr)]OTf is an efficient catalyst precursor for the α-alkylation of arylacetonitriles and methyl ketones with alcohols, which works with turnover frequencies between 675 and 176 h-1 for nitriles and between 194 and 28 h-1 for ketones.
- Buil, Maria L.,Esteruelas, Miguel A.,Herrero, Juana,Izquierdo, Susana,Pastor, Isidro M.,Yus, Miguel
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p. 2072 - 2075
(2013/09/24)
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- Metal-free, NHPI catalyzed oxidative cleavage of C-C double bond using molecular oxygen as oxidant
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A metal-free N-hydroxyphthalimide (NHPI) catalyzed aerobic oxidative cleavage of olefins has been developed. Molecular oxygen is used as the oxidant and reagent for this oxygenation reaction. This methodology has prevented the use of toxic metals or overstoichiometric amounts of traditional oxidants, showing good economical and environmental advantages. Based on the experimental observations, a plausible mechanism is proposed.
- Lin, Riyuan,Chen, Feng,Jiao, Ning
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supporting information; experimental part
p. 4158 - 4161
(2012/09/22)
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- Cross-coupling reaction of alcohols for carbon-carbon bond formation using pincer-type NHC/palladium catalysts
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A cross-coupling reaction of different alcohols was achieved using a pincer-type NHC/PdBr complex as the catalyst precursor, and the reaction, under either Ar or H2 gas, displayed a broad substrate scope with respect to both primary and secondary alcohol components, with high alcohol product selectivity. The Royal Society of Chemistry 2010.
- Kose, Osamu,Saito, Susumu
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supporting information; experimental part
p. 896 - 900
(2010/06/20)
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- Liquid-crystalline polymorphism of symmetrical azobananas: Bis(4-(4-alkylphenyl)azophenyl) 2-nitroisophtalates
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In this paper we present a series of novel compounds, bis(4-(4-alkylphenyl) azophenyl) 2-nitroisophtalates, which exhibit nematic and banana-type liquidcrystalline phases. The alkyl chain length varies from 1 to 18 carbons. The first ten members of this series exhibit nematic phase. The last eleven compounds exhibit banana-type liquid crystalline phases. The propyl and pentyl derivatives have extra second type of banana mesophase. Copyright Taylor & Francis Group, LLC.
- Zygadlo,Dardas,Nowicka,Hofmann,Galewski
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scheme or table
p. 283 - 291
(2011/08/02)
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- A ruthenium-catalyzed one-pot method for α-alkylation of ketones with aldehydes
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Ketones react with an array of aldehydes in dioxane at 80 °C in the presence of a catalytic amount of RuCl2(PPh3)3 along with KOH to give the corresponding α-alkylated ketones in moderate to good yields. A reaction pathway involving base-catalyzed cross-aldol reaction between ketones and aldehydes to form α,β-unsaturated ketones and regioselective reduction of carbon-carbon double bond of α,β-unsaturated ketones is proposed for this catalytic process.
- Cho, Chan Sik,Shim, Sang Chul
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p. 4329 - 4332
(2007/10/03)
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- Direct β-alkylation of secondary alcohols with primary alcohols catalyzed by a Cp*Ir complex
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(Chemical Equation Presented) A new catalytic system for β-alkylation of secondary alcohols has been developed. In the presence of [Cp*IrCl 2]2 (Cp* = pentamethylcyclopentadienyl) catalyst and base, the reactions of various secondary alcohols with primary alcohols give β-alkylated higher alcohols in good to excellent yields without any hydrogen acceptor or hydrogen donor. This reaction proceeds via successive hydrogen-transfer reactions and aldol condensation.
- Fujita, Ken-Ichi,Asai, Chiho,Yamaguchi, Tetsuhiro,Hanasaka, Fumihiro,Yamaguchi, Ryohei
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p. 4017 - 4019
(2007/10/03)
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- Novel Diradical-Mediated Ring Opening Reactions
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Thermo-isomerization of medium- and large-ring 1-phenylcycloalkanols 1e-i at around 650 deg C in a flow reactor system delivers the open-chain phenones 4e-i. A reaction mechanism via an open-chain diradical intermediate, followed by an intramolecular hydrogen transfer is proposed. Thermo-isomerization of α-substituted 1-phenylcyclododecanols 6 proceeds regioselectively under the formation of ω-substituted phenones 7. Furthermore, this novel hydrogen transfer reaction provides a new access to ω-substituted fatty acids.
- Rueedi, Georg,Nagel, Matthias,Hansen, Hans-Juergen
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p. 1210 - 1212
(2007/10/03)
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- Lewis acid assisted permanganate oxidations
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Lewis acids combine with permanganate in acetone solutions to form a complex that has enhanced oxidizing capabilities. The use of Lewis acids under these conditions to promote permanganate oxidations is superior to the use of Bronsted acids because the latter promote enolization of the solvent and subsequent unproductive reduction of the oxidant. The products obtained from a variety of alkenes, alkynes, arenes, sulfides, alcohols and ethers have been identified and probable reaction mechanisms proposed.
- Lai, Sheng,Lee, Donald G.
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p. 9879 - 9887
(2007/10/03)
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- Reactions of acyl tributylphosphonium chlorides and dialkyl acylphosphonates with Grignard and organolithium reagents
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Ketones and esters (4) were effectively prepared by reaction of Grignard reagents with acyl tributylphosphonium chlorides (2), diethyl acylphosphonates (5), or diisopropyl acylphosphonate (6) derived from acid chlorides and chloroformates (1). Although by the method with 2, 4 is prepared in one-pot operation from 1 and generally in a higher yield, the method with 5 or 6 proved to compensate for the synthesis of 4 with 2 in some respects. The reactivities of 2, 5, and 6 as electrophiles were also evaluated by comparing their reduction potential with those of acid chlorides.
- Maeda, Hatsuo,Takahashi, Kenji,Ohmori, Hidenobu
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p. 12233 - 12242
(2007/10/03)
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- Friedel-Crafts acylation of aromatic hydrocarbons using zeolites
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A convenient heterogeneous catalytic methodology for Friedel-Crafts acylation of benzene and toluene using various aliphatic carboxylic anhydrides over zeolites at 250°C is described. An interesting para selectivity is observed in the case of acylation of toluene over HZSM-5.
- Sreekumar,Padmakumar, Raghavakaimal
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p. 777 - 780
(2007/10/03)
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- Reactions of in situ formed acyl tributylphosphonium ions with Grignard reagents as an effective route to ketones from acid chlorides
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The reactions of acyl tributylphosphonium ions in situ generated from acid chlorides and Bu3P in THF at -22°C with primary alkyl and arylmagnesium halides have proved to be a convenient and simple procedure to prepare ketones from acid chloride in one-pot.
- Maeda, Hatsuo,Okamoto, Junko,Ohmori, Hidenobu
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p. 5381 - 5384
(2007/10/03)
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- Photoinduced Electron Transfer (PET) Promoted Cross-coupling of Organoselenium and Organosilicon Compounds: a New Carbon-Carbon Bond Formation Strategy
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PET promoted cross-coupling of organoselenium compounds and silyl enol ethers is reported.
- Pandey, Ganesh,Sochanchingwung, R.
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p. 1945 - 1946
(2007/10/02)
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- The Formation of Ketones by a Reaction Equivalent to R- + R'COCH2+ -> R'COCH2R
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A general method has been developed for the overall transformation of α-bromo ketones to α-alkyl or α-aryl ketones, with benzotriazole being used as a synthetic auxiliary, α-Benzotriazolyl ketones, when converted into their phenylhydrazones, reacted smoothly with alkyl and aryl Grignard reagents, which displaced benzotrazolate, to give the corresponding α-alkyl and α-aryl hydrazones.In some cases, these hydrolysed directly to the α-alkyl or α-aryl ketones.In each case, the product was treated with 2,4-dinitrophenylhydrazine to isolate the target ketones as the corresponding 2,4-dinitrophenylhydrazones.
- Katritzky, Alan R.,Wrobel, Leszek,Savage, G. Paul,Deyrup-Drewniak, Malgorzata
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p. 133 - 139
(2007/10/02)
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