- Robust Photocatalytic Method Using Ethylene-Bridged Flavinium Salts for the Aerobic Oxidation of Unactivated Benzylic Substrates
-
7,8-Dimethoxy-3-methyl-1,10-ethylenealloxazinium chloride (1a) was found to be a superior photooxidation catalyst among substituted ethylene-bridged flavinium salts (R=7,8-diMeO, 7,8-OCH2O-, 7,8-diMe, H, 7,8-diCl, 7-CF3 and 8-CF3). Selection was carried out based on structure vs catalytic activity and properties relationship investigations. Flavinium salt 1a proved to be robust enough for practical applications in benzylic oxidations/oxygenations, which was demonstrated using a series of substrates with high oxidation potential, i. e., 1-phenylethanol, ethylbenzene, diphenylmethane and diphenylmethanol derivatives substituted with electron-withdrawing groups (Cl or CF3). The unique capabilities of 1a can be attributed to its high photostability and participation via a relatively long-lived singlet excited state, which was confirmed using spectroscopic studies, electrochemical measurements and TD-DFT calculations. This allows the maximum use of the oxidation power of 1a, which is given by its singlet excited state reduction potential of +2.4 V. 7,8-Dichloro-3-methyl-1,10-ethylenealloxazinium chloride (1 h) can be used as an alternative photocatalyst for even more difficult substrates. (Figure presented.).
- Pokluda, Adam,Anwar, Zubair,Boguschová, Veronika,Anusiewicz, Iwona,Skurski, Piotr,Sikorski, Marek,Cibulka, Radek
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supporting information
p. 4371 - 4379
(2021/04/02)
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- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
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The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
-
supporting information
p. 9140 - 9146
(2021/11/23)
-
- Self-Assembled 2,3-Dicyanopyrazino Phenanthrene Aggregates as a Visible-Light Photocatalyst
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In this study, 2,3-dicyanopyrazino phenanthrene (DCPP), a commodity chemical that can be prepared at an industrial scale, was used as a photocatalyst in lieu of Ru or Ir complexes in C-X (X = C, N, and O) bond-forming reactions under visible-light irradiation. In these reactions, [DCPP]n aggregates were formed in situ through physical π-πstacking of DCPP monomers in organic solvents. These aggregates exhibited excellent photo- and electrochemical properties, including a visible light response (430 nm), long excited-state lifetime (19.3 μs), high excited-state reduction potential (Ered([DCPP]n*/[DCPP]n·-) = +2.10 V vs SCE), and good reduction stability. The applications of [DCPP]n aggregates as a versatile visible-light photocatalyst were demonstrated in decarboxylative C-C cross-coupling, amidation, and esterification reactions.
- He, Min,Yu, Xiaoqiang,Wang, Yi,Li, Fei,Bao, Ming
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p. 5016 - 5025
(2021/04/12)
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- Method for preparing aldehyde ketone compound through olefin oxidation
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The invention provides a method for preparing an aldehyde ketone compound by olefin oxidation, which relates to an olefin oxidative cracking reaction in which oxygen participates. The method comprises the following specific steps: in the presence of a solvent and an oxidant, carrying out oxidative cracking on an olefin raw material to obtain a corresponding aldehyde ketone product. Compared with the traditional method, the method does not need to add any catalyst or ligand, does not need to use high-pressure oxygen, has the advantages of simple and mild reaction conditions, environment friendliness, low cost, high atom economy and the like, is wide in substrate application range and high in yield, and has a wide application prospect in the aspects of synthesis of aldehyde ketone medical intermediates and chemical raw materials.
- -
-
Paragraph 0019
(2021/04/07)
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- Poly(ethylene glycol) dimethyl ether mediated oxidative scission of aromatic olefins to carbonyl compounds by molecular oxygen
-
A simple, and practical oxidative scission of aromatic olefins to carbonyl compounds using O2as the sole oxidant with poly(ethylene glycol) dimethyl ether as a benign solvent has been developed. A wide range of monosubstituted,gem-disubstituted, 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins was successfully converted into the corresponding aldehydes and ketones in excellent yields even with gram-scale reaction. Some control experiments were also conducted to support a possible reaction pathway.
- Yu, Tao,Guo, Mingqing,Wen, Simiaomiao,Zhao, Rongrong,Wang, Jinlong,Sun, Yanli,Liu, Qixing,Zhou, Haifeng
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p. 13848 - 13852
(2021/04/22)
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- Fe-S Catalyst Generated in Situ from Fe(III)- And S3?--Promoted Aerobic Oxidation of Terminal Alkenes
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An iron-sulfur complex formed by the simple mixture of FeCl3 with S3?- generated in situ from K2S is developed and applied to selective aerobic oxidation of terminal alkenes. The reaction was carried out under an atmosphere of O2 (balloon) and could proceed on a gram scale, expanding the application of S3?- in organic synthesis. This study also encourages us to explore the application of an Fe-S catalyst in organic reactions.
- Ai, Jing-Jing,Huang, Cheng-Mi,Li, Jian,Liu, Bei-Bei,Rao, Weidong,Wang, Fei,Wang, Shun-Yi
-
supporting information
p. 4705 - 4709
(2021/06/28)
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- Suzuki-Miyaura Cross-Coupling of Amides using Well-Defined, Air-Stable [(PR3)2Pd(II)X2] Precatalysts
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A versatile method for the Suzuki-Miyaura cross-coupling of amides using highly active, well-defined, and air-stable Pd?phosphine precatalysts is reported. Most notably, the method represents the first example of using practical and operationally-simple Pd(II)?phosphine precatalysts in the emerging amide bond cross-coupling manifold. The reactions are efficient at 0.10 mol% loading, furnishing biaryl ketones with high chemoselectivity for N?C(O) bond cleavage. This versatile method enables for the first time to achieve Pd?phosphine-catalyzed cross-coupling of amides at ppm loading. This C?N cross-coupling can be used to efficiently furnish pharmaceutical intermediates by orthogonal Pd-catalyzed cross-couplings. We fully expect that operationally-simple [(PR3)2Pd(II)X2] precatalysts as effective triggers for N?C(O) cross-coupling will be of broad synthetic and catalytic interest. (Figure presented.).
- Li, Guangchen,Ma, Siyue,Szostak, Michal,Zhou, Tongliang
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supporting information
(2020/05/26)
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
-
supporting information
p. 16490 - 16494
(2019/11/03)
-
- Chemoselective Synthesis of Aryl Ketones from Amides and Grignard Reagents via C(O)-N Bond Cleavage under Catalyst-Free Conditions
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Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.
- Sureshbabu, Popuri,Azeez, Sadaf,Muniyappan, Nalluchamy,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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p. 11823 - 11838
(2019/10/02)
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- A convenient and practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with formic acid as carbon monoxide source
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A practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with arylboronic acids under carbon monoxide gas-free conditions has been developed using a bidentate phosphino-functionalized magnetic nanoparticle-immobilized palladium(II) complex as catalyst. Formic acid was utilized as the carbon monoxide source with dicyclohexylcarbodiimide as the activator, and a wide variety of biaryl ketones were generated in moderate to high yields. The new heterogeneous palladium catalyst can be prepared via a simple procedure and can easily be separated from a reaction mixture by simply applying an external magnet and recycled up to 10 times without any loss of activity.
- You, Shengyong,Yan, Chenyu,Zhang, Rongli,Cai, Mingzhong
-
-
- Continuous flow synthesis of diaryl ketones by coupling of aryl Grignard reagents with acyl chlorides under mild conditions in the ecofriendly solvent 2-methyltetrahydrofuran
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An efficient continuous flow sequential synthesis of diaryl ketones was achieved by coupling of aryl Grignard reagents with acyl chlorides in the bio-derived “green” solvent 2-methyltetrahydrofuran (2-MeTHF) under mild reaction conditions (ambient temperature, 1 hour), allowing a safe and on-demand generation of 2-(3-benzoylphenyl)propionitrile with a productivity of 3.16 g hour?1
- Zhang, Chuan-Tao,Zhu, Rui,Wang, Zheng,Ma, Bing,Zajac, Adrian,Smiglak, Marcin,Xia, Chun-Nian,Castle, Steven L.,Wang, Wen-Long
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p. 2199 - 2204
(2019/01/26)
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- Sodium copper chlorophyllin catalyzed chemoselective oxidation of benzylic alcohols and diarylmethanes in water
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We report the highly efficient and chemoselective oxidation of benzylic alcohols catalyzed by sodium copper chlorophyllin in water, producing corresponding arylcarbonyl compounds. Importantly, the catalytic system exhibits a wide substrate scope and high functional group tolerance. Moreover, secondary alcohols and even diarylmethanes were smoothly oxidized to the desired aryl ketones with excellent yields.
- Liu, Shi-juan,Zhang, Miao,Lu, Rong,Li, Xiu-ying,Che, Guang-bo
-
-
- CO2-Catalyzed oxidation of benzylic and allylic alcohols with DMSO
-
CO2-catalyzed transition-metal-free oxidation of alcohols has been achieved. Earlier, several methodologies have been explored for alcohol oxidations based on transition-metal catalysts. However, owing to the cheaper price, easy separation and nontoxicity, transition-metal-free systems are in high demand to the pharmaceutical industries. For this reason, various primary and secondary alcohols have been selectively oxidized to the corresponding carbonyl compounds using CO2 as a catalyst in the presence of different functional groups such as nitrile, nitro, aldehyde, ester, halogen, ether, and so on. At the end, transition-metal-free syntheses of pharmaceuticals have also been achieved. Finally, the role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments and DFT calculations.
- Riemer, Daniel,Mandaviya, Bhavdip,Schilling, Waldemar,G?tz, Anne Charlotte,Kühl, Torben,Finger, Markus,Das, Shoubhik
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p. 3030 - 3034
(2018/04/14)
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- Pd-catalyzed Suzuki-Miyaura cross-coupling of pentafluorophenyl esters
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Although the palladium-catalyzed Suzuki-Miyaura cross-coupling of aryl esters has received significant attention, there is a lack of methods that utilize cheap and readily accessible Pd-phosphane catalysts, and can be routinely carried out with high cross-coupling selectivity. Herein, we report the first general method for the cross-coupling of pentafluorophenyl esters (pentafluorophenyl = pfp) by selective C–O acyl cleavage. The reaction proceeds efficiently using Pd(0)/phosphane catalyst systems. The unique characteristics of pentafluorophenyl esters are reflected in the fully selective cross-coupling vs. phenolic esters. Of broad synthetic interest, this report establishes pentafluorophenyl esters as new, highly reactive, bench-stable, economical, ester-based, electrophilic acylative reagents via acyl-metal intermediates. Mechanistic studies strongly support a unified reactivity scale of acyl electrophiles by C(O)–X (X = N, O) activation. The reactivity of pfp esters can be correlated with barriers to isomerization around the C(acyl)–O bond.
- Buchspies, Jonathan,Pyle, Daniel J.,He, Huixin,Szostak, Michal
-
supporting information
(2018/12/11)
-
- Copper-Catalyzed Oxidative Cleavage of Electron-Rich Olefins in Water at Room Temperature
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A copper-catalyzed oxidative cleavage of electron-rich olefins into their corresponding carbonyl derivatives is described as an alternative to ozonolysis. The scope includes various precursors to aryl ketone derivatives, as well as oxidations of enol ethers bearing atypical alkyl and dialkyl substitution, the first of their kind among such metal catalyzed alkene cleavage reactions. The use of an inexpensive copper salt, room temperature conditions, an aerobic atmosphere, and water as the global reaction medium highlight the green features of this new method. Associated mechanistic investigations are also presented.
- Lippincott, Daniel J.,Trejo-Soto, Pedro J.,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 5094 - 5097
(2018/09/13)
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- Method of utilizing continuous flow microreactor to synthesize benzophenone derivative
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The invention belongs to the technical field of organic synthesis, and particularly relates to a method of utilizing a continuous flow microreactor to synthesize a benzophenone derivative. The methodincludes: using aryl Grignard reagent and acyl chloride as raw materials; at normal temperature, continuously synthesizing the benzophenone derivative in the microreactor; recycling a reaction solvent2-methyl tetrahydrofuran. Problems of environmental pollution and reaction operation safety caused by the fact that conventional Fridel-Crafts reaction is excessively dependent on reagents like aluminum trichloride, ferric trichloride and zinc dichloride are avoided, the defect that novel catalytic processes are expensive in catalytic reagent and harsh in operation condition is made up, and continuous synthesis of a medical intermediate ketoprofen nitrile is realized efficiently. The method has the advantages of high operation convenience, high reaction safety, high yield, high efficiency andreaction solvent reusability and is environment-friendly and efficient.
- -
-
Paragraph 0041-0044; 0046
(2018/09/11)
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- Kumada Arylation of Secondary Amides Enabled by Chromium Catalysis for Unsymmetric Ketone Synthesis under Mild Conditions
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The synthesis of aromatic ketones by chromium-catalyzed Kumada arylation of secondary amides with organomagnesium reagents is described. This reaction was enabled by using low-cost chromium(III) salt as a precatalyst, combined with trimethylsilyl chloride
- Chen, Changpeng,Liu, Pei,Luo, Meiming,Zeng, Xiaoming
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p. 5864 - 5868
(2018/05/29)
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- 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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- A simple, mild and efficient oxidation of benzylic alcohols in the presence of NBS/KOAc in aqueous solution
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Background: The oxidation of benzylic alcohols to carbonyl compounds is a fundamental reaction in organic synthesis. In traditional oxidation processes, a large amount of toxic and volatile organic solvents and metal oxidants are used. Thus, developing environmentally benign oxidation processes is an important goal. N-Bromosuccinimide (NBS) is an inexpensive and convenient oxidant widely used in a variety of oxidative reactions under acidic or alkaline conditions. Methods: In this paper, we developed a simple, mild, and efficient oxidation of benzylic alcohols in the presence of N-bromosuccinimide (NBS)/KOAc in aqueous solution (H2O/CH2Cl2 = 3:1). Results: A series of benzylic alcohols were oxidized selectively to the corresponding ketones in moderate to excellent yields at room temperature. Conclusion: This reaction was carried out using a wide variety of substrates, required no metal catalyst, and proved to be tolerant towards a variety of different functional groups.
- Wu, Jianglong,Liu, Yan,Liu, Ping,Gu, Chengzhi
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p. 254 - 260
(2017/07/15)
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- Cu(II)-Catalyzed Ligand-Free Oxidation of Diarylmethanes and Second Alcohols in Water
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We developed a simple and efficient Cu(II)-catalyzed ligand-free oxidation of diarylmethanes and secondary alcohols using 70% tert-butyl hydroperoxide (TBHP) in water. A series of diarylmethanes were directly oxidized into diaryl ketones in 67%–98% yields. Additionally, various secondary alcohols were also transformed into the desired products in 48%–98% yields. Importantly, the catalytic system in the absence of any organic solvent, surfactant, or phase transfer agent, had a wide substrate scope and a high tolerance for various functional groups.
- Wu, Jianglong,Liu, Yan,Ma, Xiaowei,Liu, Ping,Gu, Chengzhi,Dai, Bin
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supporting information
p. 1391 - 139
(2017/09/30)
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- General Method for the Suzuki-Miyaura Cross-Coupling of Primary Amide-Derived Electrophiles Enabled by [Pd(NHC)(cin)Cl] at Room Temperature
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A general, highly selective method for the room temperature Suzuki-Miyaura cross-coupling of commonly encountered primary benzamides is reported. A combination of site-selective N,N-di-Boc-activation (tert-butoxycarbonyl activation) of the amide nitrogen with practical air- and moisture-stable, well-defined, and highly reactive [Pd(NHC)(cin)Cl] (NHC = N-heterocyclic carbene; cin = cinnamyl) provides a highly effective route to biaryl ketones from primary amides in high yields. For the first time, a TON of >1000 has been achieved in amide acyl cross-coupling.
- Lei, Peng,Meng, Guangrong,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
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p. 6510 - 6513
(2017/12/26)
-
- A phosphine-free, heterogeneous palladium-catalyzed atom-efficient carbonylative cross-coupling of triorganoindiums with aryl halides leading to unsymmetrical ketones
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The first phosphine-free heterogeneous palladium-catalyzed carbonylative cross-coupling of aryl halides with triorganoindiums has been developed that proceeds smoothly under 1 or 2.5 atm of carbon monoxide in THF at 68 °C and provides a general and powerful tool for the synthesis of various valuable unsymmetrical ketones with high atom-economy, good yield, and recyclability of the catalyst. Our system not only avoids the use of phosphine ligands, but also solves the basic problem of palladium catalyst recovery and reuse.
- You, Shengyong,Xiao, Ruian,Liu, Haiyi,Cai, Mingzhong
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p. 13862 - 13870
(2017/11/27)
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- Suzuki-Miyaura Cross-Coupling of N-Acylpyrroles and Pyrazoles: Planar, Electronically Activated Amides in Catalytic N-C Cleavage
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The formation of C-C bonds from amides by catalytic activation of the amide bond has been thus far possible by steric distortion. Herein, we report the first example of a general Pd-catalyzed Suzuki-Miyaura cross-coupling of planar amides enabled by the combination of (i) electronic-activation of the amide nitrogen in N-acylpyrroles and pyrazoles and (ii) the use of a versatile Pd-NHC catalysis platform. The origin and selectivity of forming acylmetals, including the role of twist, are discussed.
- Meng, Guangrong,Szostak, Roman,Szostak, Michal
-
supporting information
p. 3596 - 3599
(2017/07/15)
-
- Ni-Catalyzed Reductive Cross-Coupling of Amides with Aryl Iodide Electrophiles via C-N Bond Activation
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A Ni-catalyzed reductive cross-coupling reaction between two electrophiles, amides and aryl iodides, has been developed. This work is the first example using amide as an electrophile to couple with another electrophile, instead of using highly basic and pyrophoric nucleophiles. Furthermore, the Ni catalyst chemoselectively inserting the C-N bond of amide triggered the reductive cross-coupling reaction, which solves the problem that the Ni catalyst preferentially inserts the more reactive C-I bond to form a self-coupling product.
- Ni, Shengyang,Zhang, Wenzhong,Mei, Haibo,Han, Jianlin,Pan, Yi
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p. 2536 - 2539
(2017/05/24)
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- Metal-free oxidation of secondary benzylic alcohols using aqueous TBHP
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We report a simple, yet efficient metal-free oxidation of secondary benzylic alcohols in the presence of t-butyl hydroperoxide (70% TBHP) with high yields of up to 98%. This type of reaction can be carried out using a wide variety of substrates, requires no other organic solvent, and proves to be tolerant toward a variety of different functional groups.
- Wu, Jianglong,Liu, Yan,Ma, Xiaowei,Liu, Ping,Gu, Chengzhi,Dai, Bin
-
supporting information
p. 1747 - 1758
(2016/10/30)
-
- 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)
-
- Efficient Synthesis of Diaryl Ketones by Nickel-Catalyzed Negishi Cross-Coupling of Amides by Carbon–Nitrogen Bond Cleavage at Room Temperature Accelerated by a Solvent Effect
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The first Negishi cross-coupling of amides for the synthesis of versatile diaryl ketones by selective C?N bond activation under exceedingly mild conditions is reported. The cross-coupling was accomplished with bench-stable, inexpensive precatalyst [Ni(PPh3)2Cl2] that shows high functional-group tolerance and enables the synthesis of highly functionalized diaryl ketone motifs. The coupling occurred with excellent chemoselectivity favoring the ketone (cf. biaryl) products. Notably, this process represents the mildest conditions for amide N?C bond activation accomplished to date (room temperature, 10 min). Considering the versatile role of polyfunctional biaryl ketone linchpins in modern organic synthesis, availability, and excellent functional-group tolerance of organozinc reagents, this strategy provides a new platform for amide N?C bond/organozinc cross-coupling under mild conditions.
- Shi, Shicheng,Szostak, Michal
-
p. 10420 - 10424
(2016/07/21)
-
- Phosphine-Free, Heterogeneous Palladium-Catalyzed Atom-Efficient Carbonylative Cross-Coupling of Triarylbismuths with Aryl Iodides: Synthesis of Biaryl Ketones
-
A novel and highly efficient heterogeneous palladium-catalyzed carbonylative cross-coupling of aryl iodides with triarylbismuths has been developed that proceeds smoothly at atmospheric CO pressure and provides a general and powerful tool for the preparation of various valuable biaryl ketones with high atom economy, good to excellent yield, and recyclability of the catalyst. The reaction is the first example of Pd-catalyzed carbonylative cross-coupling for the construction of biaryl ketones using triarylbismuths as substrates.
- Hao, Wenyan,Liu, Haiyi,Yin, Lin,Cai, Mingzhong
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p. 4244 - 4251
(2016/06/09)
-
- Merging Photoredox and Nickel Catalysis: The Direct Synthesis of Ketones by the Decarboxylative Arylation of α-Oxo Acids
-
The direct decarboxylative arylation of α-oxo acids has been achieved by synergistic visible-light-mediated photoredox and nickel catalysis. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners. This mild decarboxylative arylation can also be utilized to efficiently access medicinal agents, as demonstrated by the rapid synthesis of fenofibrate. The direct decarboxylative arylation of α-oxo acids has been achieved by synergistic visible-light-mediated photoredox and nickel catalysis. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners.
- Chu, Lingling,Lipshultz, Jeffrey M.,Macmillan, David W. C.
-
supporting information
p. 7929 - 7933
(2015/06/30)
-
- DECARBOXYLATIVE CROSS-COUPLING AND APPLICATIONS THEREOF
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Methods described herein enable the production of numerous molecular species through decarboxylative cross-coupling via use of photoredox and transition metal catalysts. For example, methods described herein enable the production of numerous molecular species through decarboxylative cross-coupling via use of photoredox and transition metal catalysts. A method described herein, in some embodiments, comprises providing a reaction mixture including a photoredox catalyst, a transition metal catalyst, a coupling partner and a substrate having a carboxyl group. The reaction mixture is irradiated with a radiation source resulting in cross-coupling of the substrate and coupling partner via a mechanism including decarboxylation, wherein the coupling partner is selected from the group consisting of a substituted aromatic compound and a substituted aliphatic compound.
- -
-
Page/Page column 32; 37; 38
(2015/12/09)
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- Unmasked acyl anion equivalent from acid chloride with indium: Reversed-polarity synthesis of unsymmetric aryl aryl and alkenyl aryl ketone through palladium-catalyzed cross-coupling reaction
-
A reversed-polarity synthetic method of a range of unsymmetric aryl aryl and alkenyl aryl ketones has been developed through Pd-catalyzed cross-coupling reaction of acylindium reagents generated in situ from easily available acid chlorides and indium with various electrophiles such as aryl iodide and triflate and alkenyl triflate.
- Lee, Dohyung,Ryu, Taekyu,Park, Youngchul,Lee, Phil Ho
-
supporting information
p. 1144 - 1147
(2014/03/21)
-
- An air-tolerant approach to the carbonylative suzuki-miyaura coupling: Applications in isotope labeling
-
Carbonylative Suzuki-Miyaura coupling conditions have been developed that proceed without the exclusion of oxygen and in the presence of nondegassed and nondried solvents. By adapting the method to a two-chamber setup, the direct handling of carbon monoxide, produced from stable CO precursors, is avoided. The protocol afforded the desired benzophenones with excellent functional group tolerance and in good yields. Substituting the CO precursor, in the CO-producing chamber, with its carbon-13 labeled version generated the corresponding carbon-13 labeled benzophenones. Finally, the developed system was applied in the synthesis and isotope labeling of two pharmaceuticals, nordazepam and Tricor.
- Ahlburg, Andreas,Lindhardt, Anders T.,Taaning, Rolf. H.,Modvig, Amalie E.,Skrydstrup, Troels
-
p. 10310 - 10318
(2013/11/06)
-
- Pd(II)-Catalyzed decarboxylative cross-coupling of potassium aryltrifluoroborates with α-oxocarboxylic acids at room temperature
-
A novel Pd-catalyzed decarboxylative cross-coupling of potassium aryltrifluoroborates with R-oxocarboxylic acids is performed at room temperature. This reaction provides an efficient access to aryl ketones under mild conditions.
- Li, Mingzong,Wang, Cong,Ge, Haibo
-
supporting information; experimental part
p. 2062 - 2064
(2011/06/19)
-
- Synthesis of benzophenones from geminal biaryl ethenes using m-chloroperbenzoic acid
-
The oxidation of geminal biaryl ethenes 3 and 1,3-enynes 5 using m-chloroperbenzoic acid in dichloromethane at room temperature presents a catalyst-free approach for the synthesis of functionalized benzophenones 4 and ynones 6, respectively.
- Singh, Fateh V.,Milagre, Humberto M.S.,Eberlin, Marcos N.,Stefani, Helio A.
-
experimental part
p. 2312 - 2316
(2009/09/06)
-
- A novel Br?nsted acid catalyst for Friedel-Crafts acylation
-
Bis(trifluoroalkylsulfonylimino)trifluoromethanesulfonic acid has demonstrated remarkable catalytic ability in the electrophilic acylation of aromatic substrates. Various perfluoroalkyl substituted aroyl chlorides are employed in Friedel-Crafts acylation typically using 1 mol % of catalyst. Crown Copyright
- Posternak, Anna G.,Garlyauskayte, Romute Yu.,Yagupolskii, Lev M.
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supporting information; body text
p. 446 - 447
(2009/05/27)
-
- An alternative to the Swern oxidation
-
A variety of alcohols have been oxidized under mild conditions by the DMSO-Ph3P·X2 complexes. The reaction does not produce any Pummerer product. A mechanism for the reaction is proposed.
- Bisai, Alakesh,Chandrasekhar,Singh, Vinod K.
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p. 8355 - 8357
(2007/10/03)
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- Trifluoromethanesulfonic acid catalyzed novel friedel-crafts acylation of aromatics with methyl benzoate
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Methyl benzoate, protolytically activated by superacidic trifluoromethanesulfonic acid, reacts with aromatic compounds to give benzophenone derivatives in good to excellent yields (70-93%). Even highly deactivated nitrobenzene as well as benzotrifluoride
- Hwang, Je Pil,Surya Prakash,Olah, George A.
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p. 7199 - 7203
(2007/10/03)
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- Reactions of alcohols with cesium fluoroxysulfate
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The reactions of alcohols with cesium fluoroxysulfate (CsSO4F) in MeCN suspension were studied, and the role of the structure of the alcohol and the reaction conditions on the course of reaction was determined. Secondary benzyl alcohols bearing a nonactivating aromatic ring were selectively oxidized to the corresponding ketones, while the CsSO4F-mediated reaction of phenyl-1-naphthylmethanol resulted in the formation of 1-fluoronaphthalene and benzaldehyde. Cyclic and noncyclic secondary alcohols were readily converted to ketones, as well as 1-hydroxybenzecyclanes to benzocyclanones- 1, without any further fluorination or oxidation under the reaction conditions. On the other hand, reactions of primary alcohols with CsSO4F resulted in the formation of acid fluorides derived from further fluorination of aldehydes. Another type of transformation was observed in the case of alcohols bearing a benzyl functional group attached geminal to a hydroxy group, where decarbanylation of reactive intermediates resulting in the formation of benzyl fluoride derivatives became the main process. 2- Phenylethanol was so converted to benzyl fluoride and phenylacetyl fluoride in a 3:1 relative ratio, while 2-phenyl-1-propanol was selectively transformed to 1-phenyl-1-fluoroethane. The presence of the radical inhibitor nitrobenzene in the reaction mixture considerably inhibited conversion of the starting material. The same effect was observed by lowering the solvent polarity. Hammett correlation analysis of the effect of substituents on the reaction rates of oxidation of a set of substituted 1-phenyl-1-ethanols to acetophenones gave the reaction constant p+ = -0.32, while analysis of analogous data for the transformations of benzyl alcohols to benzoyl fluorides gave the value of -0.54. A mechanism including radical intermediates was proposed for the transformation of alcohols by CsSO4F.
- Stavber, Stojan,Kosir, Iztok,Zupan, Marko
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p. 4916 - 4920
(2007/10/03)
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- Substituent modulation of mild fluorination of aromatic molecules with caesium fluoroxysulphate
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Functionalization of mono- and di-substituted benzene derivative with CsSO4F has been modulated by substituents on the benzene ring. α-Hydroxyalkylbenzenes, with a deactivated ring, were oxidized to phenones, while fluorodealkylation was achieved in high yield when electron-donating groups were present in a para position. Electron-withdrawing substituents favoured chain fluorofunctionalization in alkylbenzenes, while ring fluorination was found exclusively in acylamino-derivatized alkylbenzenes; fluoro-addition products were formed in the case of p-alkoxy-substituted alkylbenzene derivatives.
- Stavber, Stojan,Planinsek, Zdenka,Kosir, Iztok,Zupan, Marko
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p. 409 - 412
(2007/10/02)
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- Extent of Charge Transfer in the Photoreduction of Phenyl Ketones by Alkylbenzenes
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Rate constants for triplet-state reaction of various ring-substituted benzophenones (BPs), acetophenones (APs), and α,α,α-trifluoroacetophenones (TFAs) with toluene and p-xylene have been determined by a combination of flash kinetics, steady-state quenching, and quantum yield measurements.The relative amounts of primary and tertiary radicals formed by reaction of the same ketons with p-cymene have also been measured.For all three types of ketones, rate constants correlate well with triplet ketone reduction potentials.The magnitude of the kinetic isotope effects observed with toluene-d8 and p-xylene-d10 diminishes as the ketones become easier to reduce.All of the ketone triplets react with alkylbenzenes primarily by a charge-transfer mechanism, with the rate-determining step changing from complexation to hydrogen transfer as the ketones become harder to reduce.The least reactive AP triplets probably react significantly via simple hydrogen atom abstraction as well.Those ketones with n,?* lowest triplets (all BPs and some APs) react with p-cymene to give primary/tertiary radical ratios that vary no more than a factor of 2 from the 0.40 value displayed by tert-butoxy radicals; those with ?,?* lowest triplets (TFAs and some APs) give ratios that favor primary radicals and that vary by an order of magnitude with the triplet ketone reduction potential.The variation in cymene product ratios reflect different orientations for attack on cymene by n,?* and ?,?* triplets and differing degrees of partial electron transfer within the exciplexes, which are not tight radical ion pairs.The variation seen for ?,?* triplets represents a stereoelectronic effect within face-to-face exciples, as evidenced by the excerptional behavior of p-diacylbenzenes, which give the highest ratio of tertiary radicals from cymene.There is no set intrinsic ratio of reactivity for ?,?* triplets vs. n,?* triplets in these CT reactions.The two types of triplets show similar reactivity for the more easily reduced triplets, with the harder to reduce ?,?* triplets being only one-tenth as reactive as n,?* triplets of comparable triplet reduction potential.When the extent of electron transfer in the exciplex is small, hydogen transfer is rate determining and ?,?* reactivity drops.A study of two radical reactions which generate benzyl and α-hydroxy-α-methylbenzyl radicals indicates that radical disproportionation cannot explain the low quantum yields (0.10) of most ketone-toluene photoreductions, which apparently involve substantial radiation less decay by the exciplex intermediates.
- Wagner, Peter J.,Truman, Royal J.,Puchalski, Alan E.,Wake, Ronald
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p. 7727 - 7738
(2007/10/02)
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- Process for the preparation of phenyl ketones
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A process for the preparation of phenyl ketones, characterized in that, in a first stage, a halo- or trihalomethylbenzene is reacted with a trihalomethylated aliphatic or aromatic compound in the presence of boron trifluoride in an amount such that the absolute pressure of boron trifluoride within the reaction vessel exceeds 1 bar, and in the presence of hydrofluoric acid as a solvent, and in that, in a second stage, the resultant product is hydrolyzed. The products are used as intermediates in the synthesis of compounds having a pharmaceutical or phytosanitary (e.g., herbicidal) activity.
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- Synthetic Utility of the Palladium-Catalyzed Coupling Reaction of Acid Chlorides with Organotins
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The palladium coupling of acid chlorides with unsymmetrical organotin reagents R''3SnR' can be carried out in chloroform under mild conditions in high yields to give the ketone RCOR'in which only one of the four organic groups on tin appears in the ketone product.Alkyl partners (R''= methyl or butyl) on tin serve as anchoring groups and do not transfer.When R' is acetylenic, vinyl, aryl, methoxymethylene, allyl, or benzyl, transmetalation takes place preferentially, resulting in coupling with the acyl group from the acid chloride.The reaction is tolerant of functional groups both on the acid chloride and the tin reagent.A palladium-catalyzed coupling reaction of an organotin reagent bearing acrylate functionality with an acid chloride serves as a method to introduce both a ketone and an acrylate functionality into a carbon framework.The coupling reaction of 4-(tert-butyldiphenylsiloxy)pentanoyl chloride with benzyl 3-(tributylstannyl)acrylate gave a 71percent yield of benzyl 7-(tert-butyldiphenylsiloxy)-4-oxo-2-octenoate, a precursor to the macrolide antibiotic pyrenophorin.
- Labadie, Jeff W.,Tueting, David,Stille, J. K.
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p. 4634 - 4642
(2007/10/02)
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- Deactivation of Triplet Phenyl Alkyl Ketones by Conjugatively Electron-Withdrawing Substituents
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Para-cyano, -carbomethoxy, and -acyl substituents decrease the triplet reactivity of valerophenone (γ-hydrogen abstraction), whereas comparable meta substituents increase reactivity.Spectroscopic results are presented which indicate that para-(-R) substituents lower ?,?* triplet energies so much more than n,?* energies that the lowest triplets become largely ?,?* in nature.Meta-(-R) substituents do not stabilize ?,?* triplets enough to invert triplet levels.Both substitution patterns support a largely 1,4-biradical structure for the lowest ?,?* triplet of acylbenzenes.Ortho substituents show the usual steric anomalies: ortho cyano enhances valerophenone triplet reactivity by stabilizing the n,?* triplet; ortho carbomethoxy deactivates valerophenone by stabilizing the ?,?* triplet but not the n,?.*
- Wagner, Peter J.,Siebert, Elizabeth J.
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p. 7329 - 7335
(2007/10/02)
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- Benzophenones and benzhydrols
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Compounds having the formula STR1 WHERE X is --CO-- or --CHOH--, Y and Z are halogen, alkyl, trifluoromethyl, alkoxy, hydroxy, nitro, cyano, carboxy, carbalkoxy, carbamoyl, or alkylthio, and m and n are 0, 1, or 2 Are useful in controlling undesirable secondary growth in plants, particularly sucker growth in tobacco.
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