- Isostructurality of quinoxaline crystal phases: The interplay of weak hydrogen bonds and halogen bonding
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Tailoring the physical properties of molecular crystals though the construction of solid solutions requires the existence of isostructural crystals. Simple substitutions of a given molecular framework can give a range of different crystal structures. A se
- Bowen, Richard D.,Fenwick, Nathan W.,Saidykhan, Amie,Seaton, Colin C.,Telford, Richard
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p. 7108 - 7117
(2021/10/26)
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- Catalyst-Free and Transition-Metal-Free Approach to 1,2-Diketones via Aerobic Alkyne Oxidation
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A catalyst-free and transition-metal-free method for the synthesis of 1,2-diketones from aerobic alkyne oxidation was reported. The oxidation of various internal alkynes, especially more challenging aryl-alkyl acetylenes, proceeded smoothly with inexpensive, easily handled, and commercially available potassium persulfate and an ambient air balloon, achieving the corresponding 1,2-diketones with up to 85% yields. Meanwhile, mechanistic studies indicated a radical process, and the two oxygen atoms in the 1,2-diketons were most likely from persulfate salts and molecular oxygen, respectively, rather than water.
- Shen, Duyi,Wang, Hongyan,Zheng, Yanan,Zhu, Xinjing,Gong, Peiwei,Wang, Bin,You, Jinmao,Zhao, Yulei,Chao, Mianran
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p. 5354 - 5361
(2021/05/05)
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- Ruthenium/dendrimer complex immobilized on silica-functionalized magnetite nanoparticles catalyzed oxidation of stilbenes to benzil derivatives at room temperature
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A new ruthenium/dendrimer complex stabilized on the surface of silica-functionalized nano-magnetite was fabricated and well characterized. The nano-catalyst showed good activity in the synthesis of benzil derivatives via the oxidation of stilbenes with high turnover frequency (TOF) at room temperature. Moreover, the catalyst could also be reused up to fifteen times without any loss of its activity.
- Ghanaatzadeh, Niloofar,Hashemi, Hajar,Moghadam, Majid,Niknam, Khodabakhsh,Saberi, Dariush
-
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- Unravelling mechanistic features of organocatalysis with in situ modifications at the secondary sphere
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Secondary-sphere interactions serve a fundamental role in controlling the reactivity and selectivity of organometallic and enzymatic catalysts. However, there is a dearth of studies that explicitly incorporate secondary-sphere modifiers into organocatalytic systems. In this work, we introduce an approach for the in situ systematic modification of organocatalysts in their secondary sphere through dynamic covalent binding under the reaction conditions. As a proof-of-concept, we applied boronic acids as secondary-sphere modifiers of N-heterocyclic carbenes that contained a hydroxy handle. The bound system formed in the reaction mixture catalysed the enantioselective benzoin condensations of a challenging substrate class that contains electron-withdrawing groups. Linear regression coupled with data visualization served to pinpoint the divergent origins of enantioselectivity for different substrates and decision tree algorithms served to formulate selection criteria for the appropriate secondary-sphere modifiers. The combination of this highly modular catalytic approach with machine-learning techniques provided mechanistic insights and guided the streamlined optimization process of a gram-scale reaction at low organocatalyst loading.
- Dhayalan, Vasudevan,Gadekar, Santosh C.,Alassad, Zayed,Milo, Anat
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p. 543 - 551
(2019/05/22)
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- Substituent Effect in the Synthesis of α,α-Dibromoketones, 1,2-Dibromalkenes, and 1,2-Diketones from the Reaction of Alkynes and Dibromoisocyanuric Acid
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Internal alkynes reacted with dibromoisocyanuric acid/H2O to afford α,α-dibromoketone and 1,2-diketone derivatives. Diarylalkynes with activating groups provided 1,2-diketone derivatives as the major products, whereas diarylalkynes with a non-activating group or alkylarylalkynes gave α,α-dibromoketone derivatives as the major products. In addition, diarylalkynes with deactivating groups provided 1,2-dibromoalkenes. The reaction was conducted at room temperature and showed good yields in most cases. Reaction pathways have been proposed on the basis of experimental observations and density functional theory (DFT) calculations. (Figure presented.).
- Cho, Eunjeong,Jayaraman, Aravindan,Lee, Junseong,Ko, Kyoung Chul,Lee, Sunwoo
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p. 1846 - 1858
(2019/03/07)
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- Preparing method of photocatalytic alpha-diketone compound
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The invention belongs to the technical field of medical and chemical intermediates and related chemicals, and provides a preparing method of photocatalytic alpha-diketone compound. Phenylacetylene and the derivative thereof are used as raw materials, and under the lighting condition, under the combined action of a semiconductor photocatalyst and an additive, alpha-diketone compound is generated through air oxygen in organic solvent. The preparing method has the advantages of being easy to operate, mild in condition and environmentally friendly, has probability of industrialization and obtains the alpha-diketone compound at the high yield, and the catalyst is recyclable. The alpha-diketone compound synthesized through the method can be further functionalized to obtain various compounds applied to development and research of natural products, function materials and fine chemicals.
- -
-
Paragraph 0055-0057; 0059-0061
(2017/08/28)
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- NaBrO3/bmim[HSO4]: a versatile system for the selective oxidation of 1,2-diols, α-hydroxyketones, and alcohols
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Abstract: Sodium bromate with bmim[HSO4] has been found to be an excellent oxidizing agent in aqueous medium. NaBrO3:bmim[HSO4] oxidized 1,2-diols, α-hydroxyketones, and alcohols to the corresponding carbonyl compounds in excellent yields. This method offers advantages such as low cost reagents, aqueous reaction conditions, moderate temperatures and short reaction times and hence environmentally benign reaction. Moreover, the ionic liquid bmim[HSO4] could be recycled for at least three times without loss of significant activity. Graphical abstract: [Figure not available: see fulltext.]
- Khurana, Jitender M.,Lumb, Anshika,Chaudhary, Ankita
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p. 381 - 386
(2017/02/10)
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- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of 1,2-Dicarbonyl Compounds
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A highly enantioselective hydrosilylation of 1,2-dicarbonyl compounds was successfully realized for the first time utilizing the combination of tricyclohexylphosphine and chiral alkenylborane derived in situ from diyne as a frustrated Lewis pair catalyst. A variety of optically active α-hydroxy ketones and esters were obtained in 52-98% yields with 86-99% ee's.
- Ren, Xiaoyu,Du, Haifeng
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p. 810 - 813
(2016/02/09)
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- Synthesis of ferrocene derivatives with planar chirality via palladium-catalyzed enantioselective C-H bond activation
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The first catalytic and enantioselective C-H direct acylation of ferrocene derivatives has been developed. A series of 2-acyl-1-dimethylaminomethylferrocenes with planar chirality were provided under highly efficient and concise one-pot conditions with up to 85% yield and 98% ee. The products obtained could be easily converted to various chiral ligands via diverse transformations.
- Pi, Chao,Cui, Xiuling,Liu, Xiuyan,Guo, Mengxing,Zhang, Hanyu,Wu, Yangjie
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p. 5164 - 5167
(2014/12/11)
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- Lanthanum triflate-catalyzed rapid oxidation of secondary alcohols using hydrogen peroxide urea adduct (UHP) in ionic liquid
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A convenient and efficient protocol for the oxidation of secondary hydroxyl group to ketone using hydrogen peroxide-urea adduct and catalytic (CF 3SO3)3La in ionic liquid has been developed. A number of 1,2-diols, -hydroxyketones, and other aromatic and aliphatic secondary alcohols have been successfully oxidized to the corresponding ketones using this protocol in good yields and short reaction times. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Saluja, Pooja,Magoo, Devanshi,Khurana, Jitender M.
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supporting information
p. 800 - 806
(2014/03/21)
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- CuI-catalyzed and air promoted oxidative cyclization for one-pot synthesis of polyarylated oxazoles
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A facile CuI-catalyzed and air promoted oxidative cyclization was developed for the synthesis of polyarylated oxazoles. By virtue of this method, a variety of arylated oxazoles could be easily synthesized from readily available starting materials at room temperature in air. The Royal Society of Chemistry 2013.
- Hu, Ping,Wang, Qiang,Yan, Yizhe,Zhang, Shuai,Zhang, Baiqun,Wang, Zhiyong
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supporting information
p. 4304 - 4307
(2013/08/23)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Celine,Alexakis, Alexandre
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p. 4906 - 4909,4
(2012/12/12)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Céline,Alexakis, Alexandre
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p. 4906 - 4909
(2013/01/15)
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- One-pot synthesis benzils from aldehydes via nhc-catalyzed benzoin dimerization under metal-free conditions in water
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A simple and convenient one-pot procedure is reported for the synthesis of 1,2-diketones from corresponding benzoin-type condensation reaction of aromatic aldehydes in water with N,N-dialkylbenzimidazolium salt as condensation catalyst and air as oxidizing reagent.
- Bi, Xiaoxin,Wu, Lintao,Yan, Chaoguo,Jing, Xiaobi,Zhu, Hongxiang
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scheme or table
p. 663 - 664
(2012/02/02)
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- Oxidation of benzoins to benzils using sodium hydride
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A highly efficient and eco-friendly oxidation of benzoins 1 to benzils 2 using sodium hydride has been developed.
- Joo, Cheonik,Kang, Sunhae,Kim, Sun Min,Han, Hogyu,Yang, Jung Woon
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experimental part
p. 6006 - 6007
(2010/11/21)
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- Facile route to benzils from aldehydes via NHC-catalyzed benzoin condensation under metal-free conditions
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A simple and efficient one-pot procedure for the synthesis of α-diketones from aldehydes via benzoin condensation under the influence of a catalytic amount of azolium salt combined with DBU has been developed. Thus, aldehyde was allowed to react with the azolium salt/DBU catalytic system at room temperature, and then the reaction mixture was heated to 70 °C under air atmosphere to afford the corresponding 1,2-diketone in good yield. This would be an efficient alternative method of synthesizing α-diketones from aldehydes under metal-free conditions. Crown Copyright
- Shimakawa, Yuuki,Morikawa, Takashi,Sakaguchi, Satoshi
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supporting information; experimental part
p. 1786 - 1789
(2010/05/19)
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- Novel one-pot procedure for the synthesis of 1,2-diketones
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A simple and convenient one-pot procedure is reported for the synthesis of 1,2-diketones from corresponding benzoin-type condensation reaction of aromatic aldehydes in water with N,N-dialkylbenzimidazolium salt as condensation catalyst and ferric chloride as oxidizing reagent. Copyright Taylor & Francis Group, LLC.
- Jing, Xiaobi,Pan, Xin,Li, Zhen,Shi, Yaocheng,Yan, Chaoguo
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experimental part
p. 492 - 496
(2009/06/18)
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- Oxidation of hydrobenzoins to benzils by ammonium chlorochromate/ montmorillonite K-10 under ultrasound irradiation
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The oxidation of hydrobenzoins to the corresponding benzils was carried out in excellent yield by ammonium chlorochromate (ACC) supported on montmorillonite K10 in CH2Cl2 at room temperature under ultrasound irradiation.
- Li, Ji-Tai,Sun, Xue-Li
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experimental part
p. 4321 - 4327
(2010/04/26)
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- Kinetics and mechanism of benzoin oxidation using iron(III) in the presence of ferrozine or 2,2′-bipyridine in acidic medium
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Kinetics and mechanism of oxidation of benzoin (H2B) by ferrozine (Fz) or 2,2′-bipyridine (bipy) have been carried out in aqueous HNO3 medium. The rate shows first-order dependence on [H 2B] and [Fe3+| and inverse second-order dependence on (H+). The rate of reaction increased with increase in the ligand concentration. The increase in dielectric constant will increase the rate, while increase in [HNO3] decreased it. Substituent and temperature effects on the rates have been investigated. The rate laws derived are in excellent agreement with the experimental results. Plausible mechanisms are suggested.
- Al-Sou'od, Khaldoun A.,Ali, Basem F.,Abu-El-Halawa, Rajab,Abu-Nawas, Abd-Al-Hakeem H.
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p. 444 - 449
(2007/10/03)
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- A novel decyanogenative coupling of α-cyanoimines mediated by samarium. A facile route to α-diketimines
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Conversion of α-cyanoimines 1 into α-diketimines 2 has been achieved successfully by using samarium diiodide in dry tetrahydrofuran in high yields without formation of anilinoanil 3, 1,2-diamines 4 or anilides 5.
- Thakur, Ashim J.,Prajapati, Dipak,Sandhu, Jagir S.
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p. 102 - 103
(2007/10/03)
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- Samarium diiodide promoted formation of 1,2-diketones and 1-acylamido-2-substituted benzimidazoles from N-acylbenzotriazoles
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N-Acylbenzotriazoles, when treated with samarium diiodide in THF, undergo self-coupling reaction to afford 1,2-diketones in good to excellent yields; while when treated with samarium diiodide in CH3CN, they undergo ring-opening reaction to afford 1-acylamido-2-alkyl (or aryl) benzimidazoles in reasonable to good yields. A plausible mechanism was suggested.
- Wang, Xiaoxia,Zhang, Yongmin
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p. 4201 - 4207
(2007/10/03)
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- Low-valent titanium promoted self-coupling of N-acylbenzotriazoles and their cross-coupling with diarylketones
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The self-coupling reaction of N-acylbenzotriazoles and their cross-coupling with diarylketones promoted by Sm/TiCl4 system were investigated. Self-coupling reaction could afford α-diketones or benzoins in moderate yields, while the cross-coupli
- Wang, Xiaoxia,Zhang, Yongmin
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p. 2627 - 2634
(2007/10/03)
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- Formation of 1,2-diketones by samarium diiodide promoted reaction of N-acylbenzotriazoles
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Transformation of N-acylbenzotriazoles 1 into 1,2-diketones 2 in good to excellent yields has been realized by the use of samarium diiodide at room temperature.
- Wang, Xiaoxia,Zhang, Yongmin
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p. 5431 - 5433
(2007/10/03)
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- Reduction of benzoyl tributylphosphonium chlorides by samarium diiodide as a novel access to 4-benzoylbenzaldehydes
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Addition of samarium diiodide to a well-stirred THF solution of benzoyl tributylphosphonium chlorides generated in situ from benzoyl chlorides and tributylphosphine at -40 °C gave 4-benzoylbenzaldehydes as predominant products from benzoyl chlorides without para-substituents, while benzoyl chloride bearing p-methyl or chloro groups was exclusively converted into the corresponding α-diketone.
- Maeda,Huang,Hino,Yamauchi,Ohmori
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p. 2307 - 2308
(2007/10/03)
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