- A Carbene Strategy for Progressive (Deutero)Hydrodefluorination of Fluoroalkyl Ketones
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Hydrodefluorination is one of the most promising chemical strategies to degrade perfluorochemicals into partially fluorinated compounds. However, controlled progressive hydrodefluorination remains a significant challenge, owing to the decrease in the stre
- Bi, Xihe,Sivaguru, Paramasivam,Song, Qingmin,Wang, Zikun,Zanoni, Giuseppe,Zhang, Xiaolong,Zhang, Xinyu
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- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
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A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
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p. 2134 - 2141
(2021/09/29)
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- Synthesis of Benzo-Fused Cyclic Ketones via Metal-Free Ring Expansion of Cyclopropanols Enabled by Proton-Coupled Electron Transfer
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The metal-free ring expansion of cyclopropanols containing a pendant styrene moiety was successfully achieved using a proton-coupled electron transfer enabled by an organic photoredox catalyst. Through this, variants of 1-tetralone and 1-benzosuberone bearing a substituent at the benzylic position were selectively obtained through the regioselective ring closure of alkyl radical intermediates depending on the substitution pattern of the alkene moiety.
- Kikuchi, Tomohiro,Yamada, Keiji,Yasui, Takeshi,Yamamoto, Yoshihiko
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p. 4710 - 4714
(2021/06/28)
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- Lewis acid activation of fragment-coupling reactions of tertiary carbon radicals promoted by visible-light irradiation of EDA complexes
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The addition of tertiary carbon radicals generated from N-(acyloxy)phthalimide esters to cyclic α,β-unsaturated ketones and lactones is markedly enhanced by the addition of substoichiometric amounts of a Ln(OTf)3. The reaction is accomplished by irradiation with visible light in the absence of a photosensitizer and is suggested to proceed by excitation of a ternary electron donor?acceptor complex between the NHPI ester, Hantzsch ester, and a Ln(OTf)3
- Pitre, Spencer P.,Allred, Tyler K.,Overman, Larry E.
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supporting information
p. 1103 - 1106
(2021/02/16)
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- Visible light mediated selective oxidation of alcohols and oxidative dehydrogenation of N-heterocycles using scalable and reusable La-doped NiWO4nanoparticles
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Visible light-mediated selective and efficient oxidation of various primary/secondary benzyl alcohols to aldehydes/ketones and oxidative dehydrogenation (ODH) of partially saturated heterocycles using a scalable and reusable heterogeneous photoredox catalyst in aqueous medium are described. A systematic study led to a selective synthesis of aldehydes under an argon atmosphere while the ODH of partially saturated heterocycles under an oxygen atmosphere resulted in very good to excellent yields. The methodology is atom economical and exhibits excellent tolerance towards various functional groups, and broad substrate scope. Furthermore, a one-pot procedure was developed for the sequential oxidation of benzyl alcohols and heteroaryl carbinols followed by the Pictet-Spengler cyclization and then aromatization to obtain the β-carbolines in high isolated yields. This methodology was found to be suitable for scale up and reusability. To the best of our knowledge, this is the first report on the oxidation of structurally diverse aryl carbinols and ODH of partially saturated N-heterocycles using a recyclable and heterogeneous photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Balasubramaniam, K. K.,Baskar, B.,Divya, P.,Mani Rahulan, K.,Rahman, Abdul,Sridhar, R.,Srinath, S.
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p. 5990 - 6007
(2021/08/24)
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- Palladium Complexes Bearing Chiral bis(NHC) Chelating Ligands on a Spiro Scaffold: Synthesis, Characterization, and Their Application in the Oxidative Kinetic Resolution of Secondary Alcohols
-
A series of chiral bis-N-heterocyclic carbene ligands H2[(S)-1a-d]X2 (X = Br, I) on a spiro scaffold and their palladium complexes (S)-2a-d and (S)-3a,b were prepared and applied in the enantioselective oxidative kinetic resolution of secondary alcohols. The corresponding alcohols can be obtained in high yields with moderate to excellent ee values.
- Zhang, Dao,Yu, Jueqin
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p. 605 - 613
(2020/02/13)
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- Aerobic oxidation of alcohols catalyzed by in situ generated gold nanoparticles inside the channels of periodic mesoporous organosilica with ionic liquid framework
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In situ generated gold nanoparticles inside the nanospaces of periodic mesoporous organosilica with an imidazolium framework (Au?PMO-IL) were found to be highly active, selective, and reusable catalysts for the aerobic oxidation of activated and nonactivated alcohols under mild reaction conditions. The catalyst was characterized by nitrogen adsorption-desorption measurement, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), elemental analysis (EA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst exhibited excellent catalytic activity in the presence of either Cs2CO3 (35 °C) or K2CO3 (60 °C) as reaction bases in toluene as a reaction solvent. Under both reaction conditions, various types of alcohols (up to 35 examples) including activated benzylic, primary and secondary aliphatic, heterocyclic, and challenging cyclic aliphatic alcohols converted to the expected carbonyl compounds in good to excellent yields and selectivity. The catalyst was also recovered and reused for at least seven reaction cycles. Data from three independent leaching tests indicated that amounts of leached gold particles were negligible (0.2 ppm). It is believed that the combination of bridged imidazolium groups and confined nanospaces of PMO-IL might be a major reason explaining the remarkable stabilization and homogeneous distribution of in situ generated gold nanoparticles, thus resulting in the highly active and recyclable catalyst system.
- Bigdeli, Akram,Karimi, Babak,Khodadadi Karimvand, Somaiyeh,Khorasani, Mojtaba,Safari, Ali Asghar,Vali, Hojatollah
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supporting information
p. 70 - 79
(2020/06/08)
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- Decarboxylative Intramolecular Arene Alkylation Using N-(Acyloxy)phthalimides, an Organic Photocatalyst, and Visible Light
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An intramolecular arene alkylation reaction has been developed using the organic photocatalyst 4CzIPN, visible light, and N-(acyloxy)phthalimides as radical precursors. Reaction conditions were optimized via high-throughput experimentation, and electron-rich and electron-deficient arenes and heteroarenes are viable reaction substrates. This reaction enables access to a diverse set of fused, partially saturated cores which are of high interest in synthetic and medicinal chemistry.
- Sherwood, Trevor C.,Xiao, Hai-Yun,Bhaskar, Roshan G.,Simmons, Eric M.,Zaretsky, Serge,Rauch, Martin P.,Knowles, Robert R.,Dhar, T. G. Murali
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p. 8360 - 8379
(2019/09/03)
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- On the formation of seven-membered rings by arene-ynamide cyclization
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Abstract: A Br?nsted acid-catalyzed selective arene-ynamide cyclization is described. This reaction proceeds via a keteniminium intermediate and enables the preparation of seven-membered ring enamide products. Mechanistic studies uncover an unusual product inhibition behavior. Graphical abstract: [Figure not available: see fulltext.].
- Brutiu, Bogdan R.,Bubeneck, Wilhelm Andrei,Cvetkovic, Olivera,Li, Jing,Maulide, Nuno
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- Fe(NO3)3/2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ): An efficient catalyst system for selective oxidation of alcohols under aerobic conditions
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A practical and efficient catalyst system for the oxidation of alcohols to carbonyl compounds using catalytic amounts of DDQ and Fe(NO3)3 with air as the environmentally benign oxidant has been developed. A variety of benzylic, heterocyclic, allylic and propargylic alcohols were smoothly converted into aldehydes or ketones in good to excellent yields. In case of large-scale reaction for the oxidation of benzyl alcohol, benzaldehyde was obtained in 93% isolated yield. Moreover, a possible reaction mechanism was proposed.
- Hu, Yongke,Chen, Lei,Li, Bindong
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- Design, synthesis and in vitro anti-tuberculosis activity of benzo[6,7]cyclohepta[1,2-b]pyridine-1,2,3-triazole derivatives
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A series of novel benzo[6,7]cyclohepta[1,2-b]pyridine-1,2,3-triazole hybrids (7a–j & 8a–j) have been designed and synthesized in excellent yields by Huisgen's [3+2] cyclo addition reaction of 3-(azidomethyl)-2-methyl-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-b]pyridine (5) with various alkynes 6 in presence of copper sulphate and sodium ascorbate and their structures were confirmed by IR, 1H NMR, 13C NMR and HRMS. The newly synthesized compounds 7a–j & 8a–j were evaluated for their in vitro anti-mycobacterial activity against Mycobacterium tuberculosis H37Rv (ATCC 27294). Among the compounds tested, the compounds 7i and 8g displayed most potent activity with MIC value of 1.56 μg/mL with low cytotoxicity.
- Sajja, Yasodakrishna,Vanguru, Sowmya,Vulupala, Hanmanth Reddy,Bantu, Rajashaker,Yogeswari, Perumal,Sriram, Dharmarajan,Nagarapu, Lingaiah
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p. 5119 - 5121
(2017/11/10)
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- Reactions catalyzed by a binuclear copper complex: Selective oxidation of alkenes to carbonyls with O2
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Terminal alkenes were selectively cleaved into ketones and aldehydes catalyzed by a binuclear copper catalyst bearing a simple salicylate ligand with O2 as the oxidant. The reaction was carried out under an atmosphere of O2 (balloon) with 0.5 mol% of catalyst and could be performed on a gram scale, providing a convenient and practical method for the cleavage of terminal alkenes into carbonyl compounds.
- Liu, Yuxia,Xue, Dong,Li, Chaoqun,Xiao, Jianliang,Wang, Chao
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p. 5510 - 5514
(2017/12/08)
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- Preparation method for 1-benzosuberone
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The invention provides a preparation method for 1-benzosuberone. The preparation method for the 1-benzosuberone includes the following steps that (A) a catalytic reaction is performed through a Lewis acid catalyst by taking delta-valerolactone and benzene as raw materials, the reaction temperature is controlled to be 80-90 DEG C, and the reaction time is controlled to be 12-16 h; and (B) after a quenching reaction, an organic phase is obtained through extraction, the organic phase is subjected to impurity removing and concentration treatment, and then the 1-benzosuberone is obtained. The preparation method for the 1-benzosuberone has the effects that the reaction route is short, operation is easy, the raw materials are easy to obtain, and the product is high in yield and purity.
- -
-
Paragraph 0021; 0036-0051
(2017/08/28)
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- Three-component, one-pot synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives under catalyst free conditions and evaluation of their anti-inflammatory activity
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An efficient three-component protocol is described for the synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives using β-chloroacroleins, 1,3-dicarbonyls and ammonium acetate under catalyst free conditions by using ethanol as reaction media. The mild reaction conditions, operational simplicity and high yields are the advantages of this protocol and the broad scope of this one-pot reaction makes this procedure promising for practical usages. All the final compounds were screened for anti-inflammatory activity. Among the compounds tested, the compounds 5a, 5b, 5c, 5d, 5f, and 5k exhibited significant inhibition of IL-1β and MCP-1 secretion as a measure of anti-inflammatory activity.
- Sajja, Yasodakrishna,Vulupala, Hanmanth Reddy,Bantu, Rajashaker,Nagarapu, Lingaiah,Vasamsetti, Sathish Babu,Kotamraju, Srigiridhar,Nanubolu, Jagadeesh Babu
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p. 858 - 863
(2016/05/24)
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- Highly enantioselective [3+2] coupling of cyclic enamides with quinone monoimines promoted by a chiral phosphoric acid
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Enantioselective [3+2] coupling of cyclic enamides with quinone monoimines was realised using a chiral phosphoric acid as a catalyst. This transformation allowed for the synthesis of highly enantioenriched polycyclic 2,3-dihydrobenzofurans (up to 99.9% ee). The absolute configuration of one product was determined by an X-ray crystal structural analysis. We also found a possible mechanism for this reaction.
- Zhang, Minmin,Yu, Shuowen,Hu, Fangzhi,Liao, Yijun,Liao, Lihua,Xu, Xiaoying,Yuan, Weicheng,Zhang, Xiaomei
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p. 8757 - 8760
(2016/07/15)
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- Ultrasmall Platinum Nanoparticles Supported Inside the Nanospaces of Periodic Mesoporous Organosilica with an Imidazolium Network: An Efficient Catalyst for the Aerobic Oxidation of Unactivated Alcohols in Water
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The imidazolium group inside the wall of a periodic mesoporous organosilica provides an excellent environment for the stabilization of ultrasmall Pt nanoparticles ((NP)@PMO-IL) with significant activity and recyclability in the selective aerobic oxidation of various alcohols in water at ambient pressure of oxygen. In particular, the catalyst exhibited high activity in the oxidation of unactivated primary alcohols and sterically encumbered secondary aliphatic alcohols, which remain challenging substrates for many catalytic aerobic protocols.
- Karimi, Babak,Naderi, Zahra,Khorasani, Mojtaba,Mirzaei, Hamid M.,Vali, Hojatollah
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p. 906 - 910
(2016/03/15)
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- Platinum nanoparticles supported on polymeric ionic liquid functionalized magnetic silica: effective and reusable heterogeneous catalysts for the selective oxidation of alcohols in water
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In this research, the syntheses of core-shell magnetic silica nanostructures, functionalized by a polymeric ionic liquid and immobilization of platinum nanoparticles, are described. Firstly, the magnetic silica nanoparticles were synthesized and modified using an amine-containing organosilane through a single-step process. The synthesized nanostructures were functionalized by the synthesis and polymerization of a pyridinium ionic liquid and a methyl methacrylate monomer, respectively, onto their surfaces. The platinum nanoparticles were immobilized on the functionalized nanoparticles. The obtained functionalized nanostructures have been used in the selective aerobic oxidation, in an aqueous medium, of primary and encumbered secondary aliphatic alcohols, and exhibit high activity at mild temperatures.
- Vessally, Esmail,Ghasemisarabbadeih, Mostafa,Ekhteyari, Zeynab,Hosseinzadeh-Khanmiri, Rahim,Ghorbani-Kalhor, Ebrahim,Ejlali, Ladan
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p. 106769 - 106777
(2016/11/25)
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- Highly Efficient Oxidation of Secondary Alcohols to Ketones Catalyzed by Manganese Complexes of N4 Ligands with H2O2
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The manganese complex Mn(S-PMB)(CF3SO3)2 was proven to be highly efficient in the catalytic oxidation of several benzylic and aliphatic secondary alcohols with H2O2 as the oxidant and acetic acid as the additive. A maximum turnover number of 4700 was achieved in the alcohol oxidation. In addition, the Hammett analysis unveiled the electrophilic nature of this manganese catalyst with N4 ligand. (Chemical Equation Presented).
- Shen, Duyi,Miao, Chengxia,Xu, Daqian,Xia, Chungu,Sun, Wei
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supporting information
p. 54 - 57
(2015/07/28)
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- 4-CH3CONH-TEMPO/Peracetic Acid System for a Shortened Electron-Transfer-Cycle-Controlled Oxidation of Secondary Alcohols
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We have developed a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivative catalyzed oxidation of secondary alcohols with peracetic acid as the oxidant, which was generated from H2O2 and acetic acid catalyzed by strongly acidic resins. The oxidation of alcohols proceeded well through a shortened electron-transfer cycle under metal-free conditions, avoiding the use of any other electron-transfer mediators such as halides. In addition, we demonstrated that the present system exhibited excellent efficiency under mild conditions for the oxidation of aromatic, aliphatic, and allylic secondary alcohols. Shortcut to ketones: The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-derivative-catalyzed oxidation of secondary alcohols employing peracetic acid generated from H2O2 and acetic acid with strongly acidic resins proceeds through a shortened electron-transfer cycle without halide additives. The system not only exhibits excellent efficiency at room temperature but also has a wide substrate scope.
- Zhang, Shufang,Miao, Chengxia,Xia, Chungu,Sun, Wei
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p. 1865 - 1870
(2015/06/23)
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- Synthesis of novel building blocks of benzosuberone bearing coumarin moieties and their evaluation as potential anticancer agents
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A series of novel benzosuberone bearing coumarin moieties 5a-c have been synthesized and their structures were determined by analytical and spectral (FT-IR, 1H NMR, 13C NMR, HRMS) studies. The newly synthesized compounds were evaluated for their cytotoxicity against four human cancer cell lines, A549 (Human alveolar adenocarcinoma cell line), HeLa (Human cervical cancer cell line), MDA-MB-231 (Human breast adenocarcinoma cell line), MCF-7 (Human breast adenocarcinoma cell line) and normal cell line HEK293 (Human embryonic kidney cell line). Compound 5a exhibited promising cytotoxicity with IC50 values ranging from 3.35 to 16.79 μM against all the cancer cell lines like A549, HeLa, MCF-7 and MDA-MB-231, while compound 5c showed significant cytotoxicity against HeLa and MDA-MB-231 with IC50 values of 6.72 and 4.87, respectively.
- Yadagiri, Bandi,Holagunda, Uma Devi,Bantu, Rajashaker,Nagarapu, Lingaiah,Kumar, C. Ganesh,Pombala, Sujitha,Sridhar
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p. 260 - 265
(2014/05/06)
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- Highly efficient Cu(I)-catalyzed oxidation of alcohols to ketones and aldehydes with diaziridinone
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A novel and efficient Cu(I)-catalyzed oxidation of alcohols has been achieved with di-tert-butyldiaziridinone as the oxidant under mild conditions. A wide variety of primary and secondary alcohols with various functional groups can be oxidized to aldehydes and ketones in high yields. The reaction proceeds under neutral conditions making it compatible with acid- or base-sensitive substrates, and it is amenable to gram scale.
- Zhu, Yingguang,Zhao, Baoguo,Shi, Yian
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supporting information
p. 992 - 995
(2013/04/10)
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- Enantioselective oxidation of racemic secondary alcohols catalyzed by chiral Mn(iii)-salen complexes with N-bromosuccinimide as a powerful oxidant
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We demonstrate an efficient enantioselective oxidation of secondary alcohols catalyzed by Mn(iii)-salen complex using N-bromosuccinimide (NBS) as the oxidant. The new protocol is very efficient for the oxidative kinetic resolution of a variety of secondary alcohols, including ortho-substituted benzylic alcohols. The Royal Society of Chemistry 2012.
- Xu, Daqian,Wang, Shoufeng,Shen, Zhiqiang,Xia, Chungu,Sun, Wei
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supporting information
p. 2730 - 2732
(2012/11/07)
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- Cooperative catalysis approach to intramolecular hydroacylation
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Prior examples of hydroacylation to form six- and seven-membered ring ketones require either embedded chelating groups or other substrate design strategies to circumvent competitive aldehyde decarbonylation. A cooperative catalysis strategy enabled intram
- Beletskiy, Evgeny V.,Sudheer,Douglas, Christopher J.
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experimental part
p. 5884 - 5893
(2012/09/21)
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- Synthesis and characterization of alkyl-imidazolium-based periodic mesoporous organosilicas: A versatile host for the immobilization of perruthenate (RuO4-) in the aerobic oxidation of alcohols
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The preparation and characterization of a set of periodic mesoporous organosilicas (PMOs) that contain different fractions of 1,3-bis(3- trimethoxysilylpropyl)imidazolium chloride (BTMSPI) groups uniformly distributed in the silica mesoporous framework is described. The mesoporous structure of the materials was characterized by powder X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption analysis. The presence of propyl imidazolium groups in the silica framework of the materials was also characterized by solid-state NMR spectroscopy and diffuse-reflectance Fourier-transform infrared spectroscopy. The effect of the BTMSPI concentration in the initial solutions on the structural properties (including morphology) of the final materials was also examined. The total organic content of the PMOs was measured by elemental analysis, whereas their thermal stability was determined by thermogravimetric analysis. Among the described materials, it was found that PMO with 10 % imidazolium content is an effective host for the immobilization of perruthenate through an ion-exchange protocol. The resulting Ru@PI-10 was then employed as a recyclable catalyst in the highly efficient aerobic oxidation of various types of alcohols.
- Karimi, Babak,Elhamifar, Dawood,Yari, Omolbanin,Khorasani, Mojtaba,Vali, Hojatollah,Clark, James H.,Hunt, Andrew J.
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p. 13520 - 13530
(2012/11/07)
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- Aerobic oxidative kinetic resolution of secondary alcohols with naphthoxide-bound iron(salan) complex
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The first general method for iron-catalyzed aerobic oxidative kinetic resolution of secondary alcohols was achieved with good to high enantiomeric differentiation (krel = 7-50). Although iron(salan) complex 1 does not catalyze alcohol oxidation, the naphthoxide-bound iron(salan) complex does.
- Kunisu, Takashi,Oguma, Takuya,Katsuki, Tsutomu
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experimental part
p. 12937 - 12939
(2011/10/02)
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- Ring expansion reaction of α-sulfonyl cyclic ketones via insertion of arynes into C-C: a facile and mild access to medium- and large-sized benzannulated carbocycles
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Insertion of arynes into C-C of α-sulfonyl ketones was investigated, which lead to the ring expansion reactions when α-sulfonyl cyclic ketones were used. By ring expansions and desulfonylations, medium- and large-sized benzannulated cyclic ketones were ob
- Zhang, Tiexin,Huang, Xian,Xue, Jian,Sun, Sha
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experimental part
p. 1290 - 1294
(2009/09/06)
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- Efficient synthesis of 1-tetralones from 4-arylbutyric acids by combined use of solid acid catalysts and microwave irradiation
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Solid acid catalysts such as H-Beta zeolites effectively promote dehydrative intramolecular cyclization of 4-arylbutyric acids under microwave irradiation to give 1-tetralone derivatives in high yields. Copyright
- Hiroki, Kazuaki,Hatori, Makiko,Yamashita, Hiroshi,Sugiyama, Jun-Ichi
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p. 320 - 321
(2008/09/20)
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- Green, transition-metal-free aerobic oxidation of alcohols using a highly durable supported organocatalyst
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(Chemical Equation Presented) Up-tempo catalysis: The nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) supported on the mesoporous material SBA-15 provides a highly stable and reusable catalyst (1) for the aerobic oxidation of primary, secondary, and highly hindered alcohols. The catalyst can be recovered and reused in at least another 14 reaction cycles.
- Karimi, Babak,Biglari, Abbass,Clark, James H.,Budarin, Vitaly
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p. 7210 - 7213
(2008/09/17)
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- Friedel-crafts cyclization of 1,1-difluoroalk-1-enes: Synthesis of benzene-fused cyclic ketones via α-fluorocarbocations
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1,1-Difluoroalk-1-enes bearing a phenyl group at the C-3, -4, or -5 position, readily obtained from 2,2,2-trifluoroethyl p-toluenesulfonate, are treated with FSO3H·SbF5 to undergo Friedel-Crafts cyclization in (CF3)2CHOH. The cyclization takes place via α-fluorocarbocations, followed by spontaneous hydrolysis of the C-F bond to afford bicyclic ketones including a five, six, or seven-membered ring in good yield.
- Ichikawa, Junji,Jyono, Hideharu,Kudo, Takao,Fujiwara, Masaki,Yokota, Misaki
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- Asymmetric synthesis of cyclic hydroxy ketones derived from enol ethers via sharpless asymmetric dihydroxylation. A study in the correlation of the enol ether chain length and enantioselectivity
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The Sharpless asymmetric dihydroxylation reaction of enol ethers derived from their corresponding cyclic ketones, gave α-hydroxyketones with high enantioselectivity. The enantiomeric excess was found to be proportional to the length of the unbranched enol ether chain with a maximum ee for the pentyl enol ether. An efficient synthesis of α-hydroxy chromanone in >90% ee was demonstrated using this method.
- Marcune, Benjamin F.,Karady, Sandor,Reider, Paul J.,Miller, Ross A.,Biba, Mirlinda,DiMichele, Lisa,Reamer, Robert A.
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p. 8088 - 8091
(2007/10/03)
-
- Scope of enantioselective Palladium(II)-catalyzed aerobic alcohol oxidations with (-)-sparteine
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Evaluation of the substrate scope for Pd(II)/ (-)-sparteine catalyzed aerobic oxidative kinetic resolution of secondary alcohols is disclosed. An improved system is found with use of tert-butyl alcohol solvent in which benzylic and aliphatic alcohols as well as alcohols containing olefins are effectively oxidatively resolved. For substrates that successfully undergo oxidative kinetic resolution, krel values are generally between 10 and 20. Successful scale-up of various substrates to 10-mmol scale is described. Extension to oxidative desymmetrization of 1,3-meso-diols is successful with enantiomeric excesses ranging from 78 to 85%.
- Mandal, Sunil K.,Jensen, David R.,Pugsley, Jacob S.,Sigman, Matthew S.
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p. 4600 - 4603
(2007/10/03)
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- Palladium-catalyzed aerobic oxidative kinetic resolution of alcohols with an achiral exogenous base
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Substitution of exogenous (-)-sparteine for a more practical achiral base in the aerobic oxidative kinetic resolution of secondary alcohols is described. Carbonate bases are the most effective of those screened and allow for effective kinetic resolution of benzylic, allylic, and aliphatic substrates. The procedure was also successfully extended to the oxidative desymmetrization of meso diols.
- Mandal, Sunil K.,Sigman, Matthew S.
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p. 7535 - 7537
(2007/10/03)
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- Silica Gel Supported γ-Picolinium Chlorochromate; a New and Efficient Reagent for Selective Conversion of Alcohols and Oximes into Carbonyl Compounds under Mild and Non-Aqueous Conditions
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The preparation of silica gel supported γ-picolinium chlorochromate and its application as an efficient reagent for selective oxidation of oximes and alcohols into carbonyl compounds is reported. The trimethylsilyloxy and ester groups survived under the reaction conditions.
- Salehi,Khodaei,Yazdanipoor
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p. 1281 - 1286
(2007/10/03)
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- An alternative to the Swern oxidation
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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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- Microwave promoted rapid oxidative deoximation of oximes under solvent-free conditions
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Aldeydes and ketones are easily obtained in high yields by microwave promoted rapid oxidative deoximation of the corresponding oximes with zinc nitrate hexahydrate adsorbed on silica gel under solvent free conditions.
- Tamami,Kiasat
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p. 4129 - 4135
(2007/10/03)
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- Polycyclic thiazolidin-2-ylidene amines, process for their preparation, and their use as pharmaceuticals
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Polycyclic thiazolidin-2-ylidene amines and their physiologically tolerable salts and physiologically functional derivatives of the formula I in which the radicals have the meanings indicated, and their physiologically tolerable salts and a process for their preparation are described. The compounds are suitable, for example, as anorectics.
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- Integrated chemical process: One-pot aromatization of cyclic enones by the double elimination methodology
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A variety of aromatic hydrocarbons bearing multiple alkyl substituents are accessible with perfect regiocontrol in a one-pot reaction starting from cyclo-hexenones and their aromatic analogues [Eq. (1)]. The present methodology can be further extended to the synthesis of polycyclic aromatic hydrocarbons. The drawbacks encountered in the Friedel-Crafts reaction are resolved since the reaction proceeds under basic conditions.
- Orita, Akihiro,Yaruva, Jayamma,Otera, Junzo
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p. 2267 - 2270
(2007/10/03)
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- Nafion-H catalysed intramolecular Friedel-Crafts acylation: Formation of cyclic ketones and related heterocycles
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Benzoic acids with suitable substituents bearing phenyl ring in the ortho position undergo cyclization by intramolecular Friedel-Crafts acylation in the presence of Nafion-H, a perfluorinated resinsulfonic acid catalyst. Synthesis of anthraquinone, anthrone, fluorenone, α-tetralone, 1-benzosurberone and heterocycles such as acridone, xanthone etc. is easily achieved in good to excellent yields (82-95%) by this method.
- Olah, George A.,Mathew, Thomas,Farnia, Morteza,Prakash, G. K. Surya,Katherine,Donald
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p. 1067 - 1068
(2007/10/03)
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- Formation of 1-benzosuberones by three-carbon ring expansion of benzocylobutenones
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A new method for preparing 1-benzosuberone derivatives by free radical promoted three-carbon ring expansion of benzocyclobutenones is described.
- Zhang, Wei,Gorny, Rudiger,Dowd, Paul
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p. 2903 - 2913
(2007/10/03)
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- Regioselectivity of the Base-Induced Ring Cleavage of 1-Oxygenated Derivatives of Cyclobutabenzene
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Oxy anions 3 generated from 1,2-dihydrocyclobutabenzen-1-ones 1 through addition of a charged nucleophile or from 1-hydroxy-1,2-dihydrocyclobutabenzenes 2 by deprotonation with base lead to stable products through distal and/or proximal cleavage of the strained four-membered ring via benzyl carbanion 4 and/or aryl carbanion 5. A systematic study of this process reveals the relative stability of the two isomeric carbanions 4 and 5 as a key factor in determining the course of the ring-cleavage reaction. While benzyl carbanions 4 can be trapped with carbon electrophiles, attempts at trapping aryl carbanions 5 with electrophiles other than H+ failed. In protic solvents, the magnesium salt of the tertiary alcohol 2 shows an increased rate of proximal cleavage as compared to its alkali salts. From this, we conclude that, in contrast to benzyl carbanions 4, free aryl carbanions 5 are of transient existence only. Proximal C,C-bond cleavage seems to occur either through protonation of 5 from a fast, reversible equilibrium 3?5 in which 3 strongly predominates, or in protic solvents possibly even through a rate-limiting protonation of 3 at the aromatic C-atom, bypassing free anion 5 altogether. Thus, additional factors other than just the relative stability of isomeric carbanions 4 and 5 are of importance in determining the regiochemistry of the base-induced C,C-bond cleavage in ketones 1 and in alcohols 2.
- Gokhale, Abha,Schiess, Peter
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p. 251 - 267
(2007/10/03)
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- Remote stereocontrol as a synthetic strategy: Diastereoselective annulations on an arene tricarbonylchromium template
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Stereoselective annulations on Cr(CO)3 complexed tetralone and benzosuberone derivatives have been achieved. Diastereomeric products are shown to be related by an epimerisable chiral centre. An unusually facile de-ethoxycarbonylation has been observed.
- Sur, Surojit,Ganesh, Sambasivam,Puranik, Vedavati G.,Sarkar, Amitabha
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p. 977 - 982
(2007/10/03)
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- Pyrazine-based polymeric complex of oxodiperoxochromium (VI) compound as a new stable, mild, efficient and versatile oxidant in organic synthesis
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The title compound was prepared and characterized by conventional methods. Its uses as stoichiometric oxidizing agent for a variety of organic compounds are described. With this reagent alcohols are converted to the corresponding carbonyl compounds. With 1,2-dioles C-C bond cleavage occurs. Decarboxylation of α-hydroxy acids proceeds quantitatively. Also thiols are converted to disulfides, hydroxy phenols to quinones, benzylamines to carbonyl compounds, tertiaryamines to the N-oxides, phosphines to phosphine oxides, sulfides to sulfoxides, and anthracene and phenanthrene to quinones. Deprotection of oximes and oxidative deprotection of silyl ethers proceed easily.
- Tamami, Bahman,Yeganeh, Hamid
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p. 7889 - 7896
(2007/10/03)
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- Efficient Oxidation of organic Compounds with Sodium and Silver Bromates NaBrO3, AgBrO3, in Non-Aqueous Solvents in the Presence of Lewis Acids
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The syntehtic utility of sodium and silver bromates in the presence of Lewis acids as catalysts in organic solvents is described.They are efficient for the oxidation of alcohols, acyloins, and hydroquinones to their corresponding carbonyl compounds.The oxidation coupling of thiols performs well in the absence of the catalysts.Silver bromate is able to transform primary benzylic and saturated alcohols, aldehydes, and primary benzylic carbon-hydrogen bonds to their carboxylic acids efficiently.Secondary benzylic carbon-hydrogen bonds are oxidized to their carbonyl compounds with sodium and silver bromates.
- Firouzabadi, Habib,Mohammadpoor-Baltork, Iraj
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p. 2319 - 2326
(2007/10/03)
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- New Method for Generation of β-Oxido Carbenoid via Ligand Exchange Reaction of Sulfoxides: A Versatile Procedure for One-Carbon Homologation of Carbonyl Compounds
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A new procedure for one-carbon homologation of carbonyl compounds is described.The method is based on the rearrangement of β-oxido carbenoid which is generated via the ligand exchange reaction of the sulfinyl group of α-chloro β-hydroxy sulfoxide with tert-butyllithium.Addition of the carbanion of aryl 1-chloroalkyl sulfoxides to carbonyl compounds gave the adducts in good yields.The β-oxido carbenoid rearrangement of the adducts gave one-carbon homologated carbonyl compounds having an α-alkyl substituent.A similar reaction of the adducts derived from carbonyl compounds with chloromethyl p-tolyl sulfoxide yielded a procedure for a methylene insertion.The stereochemistry of the β-oxido carbenoid rearrangenment is also discussed.
- Satoh, Tsuyoshi,Itoh, Norifumi,Gengyo, Kaoru,Takada, Sae,Asakawa, Naoyuki,et al.
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p. 11839 - 11852
(2007/10/02)
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- Fragmentation of α-Acetoximino Ketoesters in Polyphosphoric Acid
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Fragmentations of various α-acetoximino ketoesters in neat polyphosphoric acid medium to form acylium ions were studied.The resulting acylium ions were trapped by benzene rings either intermolecularly or intramolecularly. - Key Words α-Acetoximinoketoester; Acylation
- Zee, Sheng-Hsu,Chou, Shan-Yen
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p. 573 - 578
(2007/10/03)
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- Lewis acid promoted reactions. IV. Oxidation deprotection of trimethylsilyl ethers with silver and sodium bromates; AgBrO3, NaBrO3
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Primary and secondary benzylic and saturated trimethylsilyl ethers are converted to their carbonyl compounds with AgBrO3/AlCl3 efficiently. p-Hydroquinonetrimethylsilyl ether is also converted with both AgBrO3/AlCl3 and NaBrO3/AlCl3 to p-benzoquinone. AgBrO3/AlCl3 is also able to oxidize primary trimethylsilyl ethers to their carboxylic acids. Primary and secondary benzylic trimethylsilyl ethers are also converted to their carbonyl compounds with NaBrO3/AlCl3; AgBrO3 is more efficient and selective oxidant than NaBrO3.
- Firouzabadi,Mohammadpoor-Baltork
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p. 1065 - 1077
(2007/10/02)
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- Bacterial oxidation of benzocyloalkenes to yield monol, diol and triol metabolites
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Benzylic monooxygenation of benzocycloalkenes, 2-4, by enzymes in intact cultures of Pseudomonas putida UV4 yielded exclusively the [R] enantiomers, 6-8, and the derived ketones 10-12; by contrast, biotransformation of benzocyclobutene, 1, yielded both monooxygenation (5 and 9), dioxygenation (13,14 and 15), and trioxygenation (16) products.
- Boyd, Derek R.,Sharma, Narain D.,Stevenson, Paul J.,Chima, Jagdeep,Gray, David J.,Dalton, Howard
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p. 3887 - 3890
(2007/10/02)
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- Photochemistry of α-fluorocycloalkanones and α-bromo- α- fluorocycloalkanones
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Uv irradiation of a cyclohexane solution of 2-fluoro-1-indanone, 2-fluoro-1-tetralone, or 2-fluoro-1-benzosuberone resulted in the formation of a radical product (1-indanone, 1-tetralone, or 1-benzosuberone), and the degree of conversion depended on the ring size of the cycloalkanone. On the other hand, both radical as well as ionic products were formed when 2-bromo-2-fluoro derivatives of 1-indanone, 1-tetralone, or 1-benzosuberone were irradiated.
- Sket,Zupancic,Zupan
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p. 313 - 321
(2007/10/02)
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- Reactions of Carboxylic Acids with "Phosphonium Anhydrides"
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General considerations are outlined for a reagent to extract oxygen from organic molecules by an equivalent of dehydration.Reagents, (R3P+)2O, 2OTf-, were created for the purpose and subjected to a preliminary study.They were found to convert carboxylic acids readily and rapidly to anhydrides, esters, amides, amidines, benzimidazoles, and cyclic aryl ketones in good yields.
- Hendrickson, James B.,Hussoin, Md. Sajjat
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p. 1144 - 1149
(2007/10/02)
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- Novel reactions of S,S'-bis(1-phenyl-1H-tetrazol-5-yl) dithiocarbonate
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S,S'-Bis(1-phenyl-1H-5-yl) dithiocarbonate (1) was synthesized in good yield from 1-phenyl-5-mercapto-5H-tetrazole (2) and trichloromethyl chloroformate (TCF).The structure of 1 was confirmed by using X-ray crystal analysis.The reagent (1) could be applied to the formation of amides, Friedel-Crafts type reactions, isothiocyanate syntheses, and carbonyl group insertion reactions.Keywords - S,S'-bis(1-phenyl-1H-tetrazol-5-yl) dithiocarbonate; X-ray crystal analysis; amide; isothiocyanate; Friedel-Crafts reaction; carbonyl group insertion reaction.
- Takeda, Kazuyoshi,Tsuboyama, Kanoko,Takayanagi, Hiroaki,Shirokami, Rie,Takeura, Masumi,Ogura, Haruo
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p. 2334 - 2337
(2007/10/02)
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