- Rh-Catalyzed Coupling of Aldehydes with Allylboronates Enables Facile Access to Ketones
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We present herein a novel strategy for the preparation of ketones from aldehydes and allylic boronic esters. This reaction involves the allylation of aldehydes with allylic boronic esters and the Rh-catalyzed chain-walking of homoallylic alcohols. The key to this successful development is the protodeboronation of alkenyl borylether intermediate via a tetravalent borate anion species in the presence of KHF2 and MeOH. This approach features mild reaction conditions, broad substrate scope, and excellent functional group tolerance. Mechanistic studies also supported that the tandem allylation and chain-walking process were involved.
- Zhang, Kezhuo,Huang, Jiaxin,Zhao, Wanxiang
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supporting information
(2022/02/21)
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- Stepwise benzylic oxygenation via uranyl-photocatalysis
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Stepwise oxygenation at the benzylic position (1°, 2°, 3°) of aromatic molecules was comprehensively established under ambient conditions via uranyl photocatalysis to produce carboxylic acids, ketones, and alcohols, respectively. The accuracy of the stepwise oxygenation was ensured by the tunability of catalytic activity in uranyl photocatalysis, which was adjusted by solvents and additives demonstrated through Stern–Volmer analysis. Hydrogen atom transfer between the benzylic position and the uranyl catalyst facilitated oxygenation, further confirmed by kinetic studies. Considerably improved efficiency of flow operation demonstrated the potential for industrial synthetic application.
- Hu, Deqing,Jiang, Xuefeng
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supporting information
p. 124 - 129
(2022/01/19)
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- Iridium-Catalyzed Asymmetric Hydrogenation of α-Fluoro Ketones via a Dynamic Kinetic Resolution Strategy
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The discrimination of a fluorine atom from a hydrogen atom has been challenging in asymmetric catalysis. We herein report iridium-catalyzed hydrogenation of α-fluoro ketones using a strategy of dynamic kinetic resolution. Both enantiomeric and diastereomeric selectivities were satisfactory in the preparation of β-fluoro alcohols. The DFT calculation revealed a C-F···Na charge-dipole interaction in the transition state of hydride transfer. This noncovalent interaction would be responsible for the diastereomeric control.
- Tan, Xuefeng,Wen, Jialin,Zeng, Weijun,Zhang, Xumu
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supporting information
p. 7230 - 7233
(2020/10/02)
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- Manganese PNP-pincer catalyzed isomerization of allylic/homo-allylic alcohols to ketones-activity, selectivity, efficiency
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We report the first manganese catalyzed isomerization of allylic alcohols to produce the corresponding carbonyl compounds. The ligand plays a decisive role in the efficiency of this reaction. Very high conversions could be obtained using a solvent-free reaction system. A detailed DFT study reveals a self-dehydrogenation/hydrogenation reaction mechanism which was verified by the isolation of the α,β-unsaturated ketone as intermediate and a deuterium labeling experiment. It also provided a rationale for the observed selectivity and the higher efficiency of phenyl over isopropyl substitution.
- Xia, Tian,Spiegelberg, Brian,Wei, Zhihong,Jiao, Haijun,Tin, Sergey,Hinze, Sandra,De Vries, Johannes G.
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p. 6327 - 6334
(2019/11/20)
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- Additive-Free Isomerization of Allylic Alcohols to Ketones with a Cobalt PNP Pincer Catalyst
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Catalytic isomerization of allylic alcohols in ethanol as a green solvent was achieved by using air and moisture stable cobalt (II) complexes in the absence of any additives. Under mild conditions, the cobalt PNP pincer complex substituted with phenyl groups on the phosphorus atoms appeared to be the most active. High rates were obtained at 120 °C, even though the addition of one equivalent of base increases the speed of the reaction drastically. Although some evidence was obtained supporting a dehydrogenation–hydrogenation mechanism, it was proven that this is not the major mechanism. Instead, the cobalt hydride complex formed by dehydrogenation of ethanol is capable of double-bond isomerization through alkene insertion–elimination.
- Spiegelberg, Brian,Dell'Acqua, Andrea,Xia, Tian,Spannenberg, Anke,Tin, Sergey,Hinze, Sandra,de Vries, Johannes G.
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supporting information
p. 7820 - 7825
(2019/05/22)
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- Palladium-Catalyzed Carbonylative Coupling of Aryl Iodides with Alkyl Bromides: Efficient Synthesis of Alkyl Aryl Ketones
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Alkyl aryl ketones are important structures with applications in many areas of chemistry. Hence, efficient procedures for their production are particularly attractive. In this communication, a general and efficient carbonylative cross-coupling of aryl iodides and unactivated alkyl bromides is presented. By using a simple palladium catalyst, a series of alkyl aryl ketones were synthesized in moderate to excellent yields from readily available alkyl and aryl halides in an In-Ex tube with formic acid as the CO source. In this study both primary and secondary alkyl bromides/iodides were suitable coupling partners. Additionally, this method can also be employed for the late-stage functionalization of complex natural products and polyfunctionalized molecules. (Figure presented.).
- Peng, Jin-Bao,Chen, Bo,Qi, Xinxin,Ying, Jun,Wu, Xiao-Feng
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supporting information
p. 4153 - 4160
(2018/09/21)
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- Dirhodium(ii)/P(t-Bu)3 catalyzed tandem reaction of α,β-unsaturated aldehydes with arylboronic acids
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Phosphine ligated dirhodium(ii) acetate is advocated as a catalyst for the synthesis of aryl alkyl ketones by the tandem reaction of α,β-unsaturated aromatic or aliphatic aldehydes with arylboronic acids. This tandem procedure included arylation followed by the isomerization reaction. This method exhibits good functional group tolerance and has a broad substrate scope. With the conjugated aldehydes, the one-step synthesis of γ,δ-unsaturated ketones was realized through this reaction. It is noteworthy that the length of the Rh-P bond is an important factor affecting catalytic reactions. The comparative analysis of the crystal structures of axially alkylphosphane and arylphosphane ligated dirhodium(ii) acetate revealed that the shorter Rh-P bond length favors the isomerization process as compared to the longer one. In addition, the dirhodium(ii) compound can be recovered after the completion of the reaction.
- Ma, Ziling,Wang, Yuanhua
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supporting information
p. 7470 - 7476
(2018/10/24)
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- Method for preparing intermediate aryl alkyl ketone of hydroxy-ketone photoinitiator
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The invention relates to a method for preparing an intermediate aryl alkyl ketone of a hydroxy-ketone photoinitiator and particularly relates to a method for preparing (substituted) phenyl alkyl ketone. According to the method, the product is separated during reaction, the process is simple, and the production cycle is shortened; a catalyst and a solvent are easily and circularly applied mechanically; the product yield is high, and the production cost is low; and the entire reaction process is environmentally friendly.
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Paragraph 0020
(2018/07/30)
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- Synthetic method of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone
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The invention discloses a synthetic method of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone. The synthetic method comprises the following steps: (1) carrying out a Friedel-Crafts reaction on chlorobenzene with n-butyryl chloride under the catalysis of aluminium trichloride to obtain a compound I; (2) carrying out a bromination reaction on the compound I with bromine under the action ofa catalytic oxidizing agent to obtain a compound II; (3) carrying out a substitution reaction on the compound II with dimethylamine to obtain a compound III; (4) carrying out a quaternization reactionon the compound III with benzyl chloride to obtain a compound IV; (5) carrying out a substitution reaction on the compound IV with morpholine under the action of a composite catalyst to obtain a compound V; and (6) carrying out a rearrangement reaction on the compound V under the action of an alkali so as to obtain the 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone. The synthetic methodprovided by the invention has the advantages of mild technological condition, simple operation, high selectivity and high total yield.
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Paragraph 0026; 0050-0052; 0078-0080
(2018/09/08)
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- Continuous preparation method for 1-(4-chlorphenyl)-1-butanone
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In order to overcome the shortcoming of a lot of three wastes existing in friedel-crafts reaction preparation method, the invention provides a continuous preparation method for 1-(4-chlorphenyl)-1-butanone. The preparation method for the first time employs the process of continuous adding of mixed acid into 4-chlorobenzoic acid, n-butyric acid and manganese oxide for condensation reaction to replaces the original method of preparation of 1-(4-chlorophenyl)-1-butanone by friedel-crafts reaction of chlorobenzene and n-butyryl chloride under the catalysis of anhydrous aluminum trichloride. The operation method greatly improves the reaction safety and production capacity, the catalyst can be used continuously for a long time, and with the advantages of environmental friendliness, low cost, simple operation, high yield, etc., the method can better meet the current increasing market demands.
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Paragraph 0014; 0016; 0019; 0021; 0022
(2018/01/11)
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- A new amino ketone photoinitiator and in UV - LED light curing system application (by machine translation)
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The invention provides a method suitable for UV - LED light source setting new amino ketone photo initiator, can in long wave zone (365 - 395 nm) has stronger absorption, UV - LED light source is suitable for curing, has overcome the traditional cured high energy consumption, pollution and shortcomings. Electronic unlocalized is good, with strong intramolecular electron transfer performance and excellent photoelectric nature, in the long-wave region 365 nm - 395 nm range have strong absorption, is suitable for high-power UVLED ultraviolet light curing system, compared with the prior art such optical initiator has a considerable advantage. (by machine translation)
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Paragraph 0071; 0072
(2017/08/25)
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- Sodium Bromide-Catalyzed Oxidation of Secondary Benzylic Alcohols Using Aqueous Hydrogen Peroxide as Terminal Oxidant
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A halide salt, hydroperoxide and AcOH catalyst system was applied to the oxidation of secondary benzylic alcohols. This simple system can be applied to a variety of secondary benzylic alcohols and scaled up for gram-scale preparation. High secondary benzylic alcohol selectivity of the present method is demonstrated in hydroxyketone synthesis. Based on several experimental results, a catalytic cycle for our oxidation is proposed.
- Komagawa, Hiromi,Maejima, Yukako,Nagano, Takashi
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p. 789 - 793
(2016/03/09)
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- Vanadium-catalyzed green oxidation of benzylic alcohols in water under air atmosphere
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The oxidation of alcohols using catalytic amounts of metal complexes is highly attractive from the viewpoint of green chemistry principles. However, examples of metal complex-catalyzed oxidations of alcohols with O2 using water as the solvent are still rare, and precious metals, high-pressure O2 or air, and a stoichiometric amount of base are often required. In this study, it was found that an oxovanadium-4,4′-t-Bubpy (4,4′-di-tert-butyl-2,2′-bipyridyl) complex exhibited high catalytic activity in the oxidation of benzhydrols under an atmosphere of O2 in water as the sole solvent. Interestingly, this catalytic oxidation method could be applied to the gram-scale aerobic oxidation of alcohols in water under the atmosphere.
- Marui, Kuniaki,Higashiura, Yuuki,Kodama, Shintaro,Hashidate, Suguru,Nomoto, Akihiro,Yano, Shigenobu,Ueshima, Michio,Ogawa, Akiya
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p. 2431 - 2438
(2014/04/03)
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- Palladium-catalyzed oxidative coupling of trialkylamines with aryl iodides leading to alkyl aryl ketones
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Chemical equations presented. A new, simple method for selectively synthesizing alkyl aryl ketones has been developed by palladium-catalyzed oxidative coupling of trialkylamines with aryl iodides. In the presence of PdCl2(MeCN)2, TBAB, and ZnO, a variety of aryl iodides underwent an oxidative coupling reaction with tertiary amines and water to afford the corresponding alkyl aryl ketones in moderate to excellent yields. It is noteworthy that this method is the first example of using trialkylamines as the carbonyl sources for constructing alkyl aryl ketone skeletons.
- Liu, Yan,Yao, Bo,Deng, Chen-Liang,Tang, Ri-Yuan,Zhang, Xing-Guo,Li, Jin-Heng
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supporting information; experimental part
p. 2184 - 2187
(2011/06/20)
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- A facile cleavage of ketone N,N-dimethylhydrazones by CeCl3·7H2O-SiO2
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Ketone N,N-dimethylhydrazones are rapidly and chemoselectively deprotected to the corresponding ketones in high yields by CeCl3·7H2O supported on silica gel under microwave irradiation. The method is compatible with acid sensitive substrates.
- Yadav,Subba Reddy,Reddy,Sabitha
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p. 1134 - 1136
(2007/10/03)
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- Ruthenium-catalyzed isomerization of homoallylic alcohols in water
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Through the catalysis of RuCl2(PPh3)3, the functional groups of homoallylic alcohols are repositioned to give allylic alcohols with controlled regioselectivity. The reaction proceeds most efficiently in an aqueous media. The selectivity in product formation is affected by the reaction temperature and the amount of the catalyst being used. A higher reaction temperature and the use of a smaller amount of the catalyst are preferable for the formation of allylic alcohols. The reaction process was postulated as a tandem olefin migration-allylic rearrangement. Under the same reaction conditions, the functional groups of allylic alcohols undergo allylic rearrangements.
- Wang, Dong,Chen, Dongli,Haberman, John X.,Li, Chao-Jun
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p. 5129 - 5142
(2007/10/03)
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- Photoinduced radical cleavage of bromophenyl ketones
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Several bromophenyl alkyl ketones undergo photoinduced radical cleavage of bromine atoms; the resulting acylphenyl radicals are trapped as the dehalogenated ketones either by alkane solvents or by added thiols. Quantum yields for this process decrease with increasing solvent viscosity; this behavior indicates that recoupling of the phenyl/ bromine radical pairs competes with their diffusion apart. In some cases Norrish type II elimination competes with the cleavage reaction. Steady state studies indicate room temperature rate constants for triplet state C-Br radical cleavage of 2 and 1 × 108 s-1, respectively, for m- and p-bromoacetophenone. Flash kinetics measurements of the temperature dependence for their triplet decay provided activation parameters for triplet state cleavage: ΔS? = -5 eu for the para isomer and -3 eu for the meta; ΔH? = 5.3 kcal/mol for both. The values for the meta isomer are the same in methanol and toluene and extrapolate to the room temperature decay rate measured by steady state techniques. The 0.002-0.003 quantum yields for conversion of m- and p-bromobenzophenone to benzophenone in cyclopentane solvent indicate triplet state cleavage rates of 0.8-1.0 × 105 s-1, which would suggest ΔH? values near 10 kcal/mol. Consideration of triplet excitation energies and of the phenyl-Br bond strength suggests a mechanism for triplet cleavage involving activated C-Br bond stretching in the triplets until a π,π* configuration is converted into a dissociative nπBr,σ* state. It is suggested that the different isomers have comparable mixing of nπBr,π* character into their π,π* triplets and that the state interconversions occur inefficiently at surface crossings with a nπBr,σ* state. The o-bromo ketones show unusual behavior. The Arrhenius plot for triplet decay of o-bromoacetophenone is curved and only half the total cleavage can be quenched by naphthalene. o-Bromobenzophenone is 500 times more reactive than its isomers; direct interaction between bromine and carbonyl as well as steric depression of the C-Br dissociation energy may both contribute to this unusual reactivity.
- Wagner, Peter J.,Sedon, James H.,Gudmundsdottir, Anna
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p. 746 - 754
(2007/10/03)
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- A Convenient and Efficient Unsymmetrical Ketone Synthesis from Acid Chlorides and Alkyl Iodides Catalyzed by Palladium
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Unsymmetrical ketones are prepared in good or excellent yields by a palladium catalyzed coupling reaction of acid chlorides and alkyl iodides meditated by Zn-Cu couple.
- Tamaru, Yoshinao,Ochiai, Hirofumi,Sanda, Fumio,Yoshida, Zen-ichi
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p. 5529 - 5532
(2007/10/02)
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- Substituted (2-Phenoxyphenyl)acetic Acids with Antiinflammatory Activity. 1
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The synthesis and antiinflammatory activity of a series of substituted (2-phenoxyphenyl)acetic acids are described.Initial screening in the adjuvant arthritis test showed that halogen substitution in the phenoxy ring enhanced activity considerably.Ulcerogenic potential, as measured by the minimum ulcerogenic dose (MUD), was low in almost all the acids tested. acetic acid possessed the most favorable combination of potency with low toxicity, including ulcerogenicity, and this compound is now in therapeutic use.
- Atkinson, David C.,Godfrey, Keith E.,Meek, Bernard,Saville, John F.,Stillings, Michael R.
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p. 1353 - 1360
(2007/10/02)
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- NOVEL REARRANGEMENTS OF α-N-ALKYLAMIDO-SUBSTITUTED SULFIDES AND SULFONES
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The present paper describes novel rearrangements of α-N-alkylamido-substituted sulfides and sulfones promoted by strong bases such as NaH, lithium diisopropylamide and butyllithium, where the alkyl group linked to the sulfur migrates to the amide carbonyl carbon to give the corresponding ketones.The reactions are established as intramolecular rearrangements, and the mechanism is discussed.Keywords: - alkyl (N-alkylamido)methyl sulfide; alkyl (N-alkylamido)methyl sulfone; alkyl α-(N-alkylamido)benzyl sulfide; intramolecular rearrangement; sodium hydride; lithium diisopropylamide; butyllithium
- Ishikawa, Yoshiharu,Kurebayashi, Yasuo,Suzuki, Kunio,Terao, Yoshiyasu,Sekiya, Minoru
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p. 2496 - 2502
(2007/10/02)
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