- The room temperature formation of gold nanoparticles from the reaction of cyclohexanone and auric acid; A transition from dendritic particles to compact shapes and nanoplates
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A new straightforward method for the synthesis of gold nanoparticles from addition of cyclohexanone to aqueous solutions of auric acid at room temperature is presented. By understanding this process we have discovered a new organic chemistry transformation reaction for converting cyclic ketones to α-chloro ketones and a mechanism for the nanoparticle formation. Contrary to conventional gold nanoparticle syntheses, the reaction self- initiates at room temperature and forms an increasingly red solution over ≈60 minutes. By studying the gold colloid's formation using transmission electron microscopy it was observed that large dendritic (63 ± 21 nm diameter) structures made of clustered particles (6 ± 1 nm) were initially formed. These dendritic particles then compacted into an array of denser shapes that slowly increase in size until the reaction is complete. The most prominent shapes observed were spheres (43 ± 7 nm); other shapes included dodecahedra (39 ± 10 nm) triangular (≈50 nm in height) and hexagonal (≈70 nm wide) nanoplates. The solution was stable to precipitation for over 3 months. During this period the nanoplate structures substantially increased in size (triangular ≈ 250 nm, hexagonal ≈ 320 nm) whereas other structures showed no further growth. X-ray diffraction studies demonstrated that the gold nanoparticles were crystalline. The formation of the 2-chlorocyclohexanone by-product was observed in solution phase 1H & 13C NMR, gas phase chromatography and IR spectroscopy. A mechanism is presented to account for this by-product and the reduction of auric acid to gold. The Royal Society of Chemistry 2013.
- Uppal, Madeeha A.,Kafizas, Andreas,Ewing, Michael B.,Parkin, Ivan P.
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Read Online
- Synthesis of Ti-Al binary oxides and their catalytic application for C-H halogenation of phenols, aldehydes and ketones
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Traditional C–H halogenation of organic compounds often requires corrosive agent or harsh condition, and current researches are focused on the use of noble metals as catalyst. In order to give an efficient, benign, activity-adjustable and cost-effective system for halogenation, a series of Ti-Al mixed oxides are prepared as catalyst through sol-gel in this work. Characterizations reveal all catalysts contain more aluminum than titanium, but preparative conditions affect their composition and crystallinity. Monitoring of particle size, zeta potential and UV–vis of preparative solution reveals that formation of catalyst colloids undergoes chemical reaction, affecting catalyst morphology. In halogenation, all catalysts show moderate to high activities, copper chloride proves to be an effective halogen source rather than sodium chloride. The chlorination and bromination are better than iodization, phenol and ketone appear to be more appropriate substrates than aldehyde. Additionally, oxide backbone of catalyst is more durable than its organic components during recycling. This study may provide new catalytic materials for progress of C–H activation.
- Su, Peigen,Fan, Chao,Yu, Heng,Wang, Wanqin,Jia, Xin,Rao, Qifan,Fu, Chenxi,Zhang, Donghua,Huang, Benhua,Pan, Cheng,Zheng, Aqun,Sun, Yang
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- Efficient α-chlorination of carbonyl containing compounds under basic conditions using methyl chlorosulfate
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An efficient method for the α-chlorination of ketones under basic conditions is described using methyl chlorosulfate. Its applicability for the chlorination of other functional groups has also been studied and it is equally useful for the synthesis of α-chloroesters and amides. Methyl chlorosulfate is described for the first time as a positive chlorine source. Some aldol reactions which occur during the chlorination of some substrates are also reported.
- Silva, Saúl,Maycock, Christopher D.
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supporting information
p. 1233 - 1238
(2018/02/27)
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- Method for preparing o-chlorocyclohexanone by using cyclohexanone by-product lightweight oil
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The invention discloses a method for preparing o-chlorocyclohexanone through lightweight oil, wherein the lightweight oil is the by-product obtained from cyclohexanone preparation through oxidation ofcyclohexane, and the o-chlorocyclohexanone is prepared in the presence of an auxiliary agent and a catalyst by completely utilizing the cyclohexene oxide in the lightweight oil through ring opening,oxidation and other reactions. According to the present invention, with the method, the disadvantages of more impurities, harsh reaction condition or complex product purification and the like in the prior art are solved. The method comprises: in the presence of an auxiliary agent, carrying out a reaction on lightweight oil containing 1 mole of cyclohexene oxide and 1-2 moles of a hydrogen chloridesolution for 1-4 h at a temperature of 10-60 DEG C to generate 2-chlorocyclohexanol, distilling to remove the relatively low boiling point components to obtain high-purity 2-chlorocyclohexanol, carrying out a reaction on the high-purity 2-chlorocyclohexanol as a raw material and a certain amount of an oxidizing agent, washing, separating, rectifying, and collecting the distillate at a temperatureof 203-204 DEG C to obtain the o-chlorocyclohexanone with the purity of more than 99%, wherein the yield of the o-chlorocyclohexanone is more than 90%.
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Paragraph 0016; 0017; 0018; 0019; 0020
(2018/04/01)
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- Ammonium Tungstate as an Effective Catalyst for Selective Oxidation of Alcohols to Aldehydes or Ketones with Hydrogen Peroxide under Water - A Synergy of Graphene Oxide
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Ammonium tungstate was found to be a facile and efficient catalyst for selective oxidation of alcohols to the corresponding carbonyl compounds with hydrogen peroxide as oxidant. Heterogeneous graphene oxide as acid effectively intensified the transformations and resulted in excellent yields. The use of water as solvent rendered the reactions promising both economically and environmentally.
- Fu, Huihui,Hu, Chuanfeng,Huang, Zhida,Zhou, Jianhao,Peng, Xinhua
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supporting information
p. 447 - 451
(2017/11/27)
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- Rearrangement Reaction Based on the Structure of N-Fluoro- N-alkyl Benzenesulfonamide
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A novel rearrangement reaction based on the structure of N-fluoro-N-alkyl benzenesulfonamide was developed. The reaction proceeded readily at 50 °C in formic acid and generated a variety of benzenesulfonamides and aldehydes or ketones simultaneously. The reaction mechanism is believed to be a concerted mechanism that consist of 1,2-aryl migration with the departure of fluorine anion via an SN2 mechanism. This rearrangement reaction features an interesting reaction mechanism, mild reaction conditions, simple operations, and a broad substrate scope.
- Wang, Han-Ying,Pu, Xiao-Qiu,Yang, Xian-Jin
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p. 13103 - 13110
(2018/10/20)
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- Trichloromethanesulfonyl chloride: A chlorinating reagent for aldehydes
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Trichloromethanesulfonyl chloride (CCl3SO2Cl), a commercially available reagent, has been found to perform efficiently in the α-chlorination of aldehydes, including its catalytic asymmetric version, under very mild reaction conditions. Under our reaction conditions, this compound outperforms typical chlorinating reagents for organic synthesis, facilitates workup and purification of the product, and minimizes the formation of toxic, chlorinated organic waste.
- Jimeno, Ciril,Cao, Lidong,Renaud, Philippe
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p. 1251 - 1255
(2016/02/19)
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- Direct conversion of alcohols to α-chloro aldehydes and α-chloro ketones
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Direct conversion of primary and secondary alcohols into the corresponding α-chloro aldehydes and α-chloro ketones using trichloroisocyanuric acid, serving both as stoichiometric oxidant and α-halogenating reagent, is reported. For primary alcohols, TEMPO has to be added as an oxidation catalyst, and for the transformation of secondary alcohols (TEMPO-free protocol), MeOH as an additive is essential to promote chlorination of the intermediary ketones.
- Jing, Yuanyuan,Daniliuc, Constantin G.,Studer, Armido
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supporting information
p. 4932 - 4935
(2015/04/27)
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- Development of a generic activation mode: Nucleophilic α-substitution of ketones via oxy-allyl cations
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Oxy-allyl cations have been known as transient electrophilic species since they were first proposed as intermediates in the Favorskii rearrangement in 1894. Since that time, they also have been used as a mode of activation for [4 + 3] cycloadditions in a variety of natural product syntheses. In this manuscript, we describe a method for the interception of oxy-allyl cations with a diverse range of common nucleophiles, thereby demonstrating the value of this intermediate as a generic mode of activation. This simple, mild, room temperature protocol allows for the formation of a variety of high value carbon-carbon and carbon-heteroatom bonds that are readily incorporated within a series of cyclic and acyclic ketone systems. Initial efforts into the development of an enantioselective catalytic variant are also described.
- Vander Wal, Mark N.,Dilger, Andrew K.,Macmillan, David W. C.
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p. 3075 - 3079
(2013/07/26)
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- Iridium-catalyzed 1,3-hydrogen shift/chlorination of allylic alcohols
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Tandem: Allylic alcohols react with N-chlorosuccinimide (NCS) in a tandem 1,3-H shift/C-Cl bond formation leading to α-chloroketones and α-chloroaldehydes. The reactions proceed with complete selectivity to give single constitutional isomers of monochlorinated carbonyl compounds. The utility of the transformation is illustrated by the straightforward synthesis of 4,5-disubstituted 2-aminothiazoles from allylic alcohols. Copyright
- Ahlsten, Nanna,Gomez, Antonio Bermejo,Martin-Matute, Belen
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supporting information
p. 6273 - 6276
(2013/07/05)
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- METHOD FOR SYNTHESIS OF N-ALKYL CARBAZOLE AND DERIVATIVES THEREOF
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Disclosed is a process for the preparation of N-alkyl carbazole. Said process comprises: a) chlorinating cyclohexanone to form 2-chlorocyclohexanone; b) reacting 2-chlorocyclohexanone with N-ethyl aniline to form 2-(N-ethyl anilino) cyclohexanone; c) cyclizing 2-(N-ethyl anilino) cyclohexanone by refluxing with simultaneous water removal to obtain 9-ethyltetrahydrocarbazole; d) treating 9-ethyl-tetrahydrocarbazole with concentrated hydrochloric acid followed by water wash for removing N-ethyl aniline; e) dehydrogenating 9-ethyltetrahydrocarbazole by heating 9-ethyltetrahydrocarbazole in a solvent, in presence of a catalyst to obtain N-alkyl carbazole.
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Page/Page column 10-11
(2011/04/14)
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- Rate coefficients and products for gas-phase reactions of chlorine atoms with cyclic unsaturated hydrocarbons at 298 K
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Rate coefficients for the reaction of Cl atoms with cycloalkenes have been determined using the relative rate method, at 298 K and atmospheric pressure of N2. Reference molecule was n -hexane, and the concentrations of the organics were followed by gas chromatographic analysis. Cl atoms were prepared by photolysis of trichloroacetyl chloride at 254 nm. The relative rates of reactions of Cl atoms with cycloalkenes, with, respect to M-hexane, are measured as 1.12 ±0.38, 1.31 ±0.14, and 1.69±0.18forcyclopentene, cyclohexene, and cycloheptene, respectively. Considering the absolute value of the rate coefficient of the reaction of Cl atom with n-hexane as 3.03 ± 0.06 × 10-10 cm3 molecule-1 s -1, the rate coefficient values for cyclopentene, cyclohexene, and cycloheptene are calculated, to be (3.39 ± 1.08) × 10 -10, (3.97 ±0.43) × 10-10, and (5.12 ± 0.55) × 10-10 cm3 molecule-1 S -1', respectively. The experiments for each, molecule were repeated six to eight times, and the slopes and the rate coefficients given above are the average values of these measurements, and the quoted error includes 2σ as well as all other uncertainties in the measurement and calculations. The rate coefficient increases linearly with the number of carbon atoms, with an increment per additional CH2 group being (8.7 ± 1.6) × 11-12 cm3 molecule-1 s-1. Chloroketones and chloroalcohols, along with unsaturated, ketones and alcohols, were found to be the major products of Cl-atom-initiated oxidation of cycloalkenes in the presence of air. The atmospheric implications of these results are discussed, along with a comparison with the reported structure activity relationships.
- Sharma,Pushpa,Dhanya,Naik,Bajai
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body text
p. 98 - 105
(2011/06/21)
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- Rapid and catalyst-free α-halogenation of ketones using N-halosuccinamides in DMSO
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α-Halogenation of various carbonyl compounds such as β-keto-esters, cyclic ketones, and lactams with N-halosuccinamides (NBS, NCS, NIS) in the presence of DMSO proceeded very smoothly to give the corresponding α-monohalogenated products in good to excellent yields with high selectivity under catalyst-free conditions. Copyright Taylor & Francis Group, LLC.
- Sreedhar,Reddy, P. Surendra,Madhavi
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p. 4149 - 4156
(2008/03/13)
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- Halogenation of carbonyl compounds by an ionic liquid, [AcMIm]X, and Ceric Ammonium Nitrate (CAN)
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An ionic liquid, acetylmethylimidazolium halide ([AcMIm]X), in combination with ceric ammonium nitrate promotes halogenations of a wide variety of ketones and 1,3-keto esters at the ?-position. The ionic liquid acts here as reagent as well as reaction medium, and thus the reaction does not require any organic solvent or conventional halogenating agent. The reaction is completely arrested when the radical quencher TEMPO is used. A plausible radical mechanism is also suggested. CSIRO 2007.
- Ranu, Brindaban C.,Adak, Laksmikanta,Banerjee, Subhash
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p. 358 - 362
(2008/02/13)
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- A green approach for efficient α-halogenation of β-dicarbonyl compounds and cyclic ketones using N-halosuccinimides in ionic liquids
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Room temperature ionic liquids (ILs) are used as a green recyclable reaction media for the α-monohalogenation of 1,3-diketones, β-keto-esters and cyclic ketones with N-halosuccinimides in excellent yields in the absence of a catalyst. The recovered ionic liquid was reused five to six times with consistent activity.
- Meshram,Reddy,Vishnu,Sadashiv,Yadav
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p. 991 - 995
(2007/10/03)
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- Selenium-catalyzed oxidative halogenation
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Organoselenides catalyze the oxidation of halides by H2O2. Furthermore, these selenides catalyze the transfer of oxidized halogens from N-halosuccinimides to olefins and ketones. Thus, organoselenides catalyze oxidative halogenation reactions including halolactonization, α-halogenation of ketones, and allylic halogenation. The ability of selenium to undergo reversible 2e- oxidation-reduction chemistry facilitates halogenation through selenium-bound halogen intermediates.
- Mellegaard-Waetzig, Shelli R.,Wang, Chao,Tunge, Jon A.
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p. 7191 - 7198
(2007/10/03)
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- Microwave-assisted synthesis of α-hydroxy ketone and α-diketone and pyrazine derivatives from α-halo and α,α′-dibromo ketone
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A novel reaction of α-halo ketone (α-bromo and α-chloro ketone) with irradiation under microwave gave the corresponding α-hydroxyketone and pyrazine derivative in good yields. In the case of α,α′-dibromo ketone, α-diketone was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxyketone, α-diketone, α-chloro ketone and pyrazine derivative.
- Utsukihara, Takamitsu,Nakamura, Hiroaki,Watanabe, Masashige,Akira Horiuchi
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p. 9359 - 9364
(2008/01/27)
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- Amberlyst-15-promoted efficient 2-halogenation of 1,3-keto-esters and cyclic ketones using N-halosuccinimides
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A simple and rapid process has been developed for the α- monohalogenation of 1,3-keto-esters with N-halosuccinimides catalyzed by Amberlyst-15 at room temperature to produce the corresponding 2-halo 1,3-keto-esters in high yields. This protocol also extended to α-halogenation of cyclic ketones.
- Meshram,Reddy,Sadashiv,Yadav
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p. 623 - 626
(2007/10/03)
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- Efficient microwave induced direct α-halogenation of carbonyl compounds
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A novel and direct method for the synthesis of α-halocarbonyl compounds using sequential treatment of carbonyl compounds with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation conditions is described.
- Lee, Jong Chan,Park, Jin Young,Yoon, So Young,Bae, Yong Hun,Lee, Seung Jun
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p. 191 - 193
(2007/10/03)
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- Highly enantioselective direct organocatalytic α-chlorination of ketones
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A C2-symmetric diamine serves as the organocatalyst in an asymmetric α-chlorination reaction of simple ketones (e.g., cyclohexanone, diethyl ketone). Optically active α-chloroketones are formed with excellent enantioselectivities using N-chlorosuccinimide (NCS) as the chlorine source (see scheme). These products have broad synthetic utility, in particular for pharmaceutical applications.
- Marigo, Mauro,Bachmann, Stephan,Halland, Nis,Braunton, Alan,Jorgensen, Karl Anker
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p. 5507 - 5510
(2007/10/03)
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- Oxidative transformation of 1,3-dioxacycloalkanes induced by chlorine dioxide
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The products and kinetic regularities of the reactions of 1,3-dioxacycloalkanes with chlorine dioxide were studied. The effects of the nature of solvent and the temperature on the reaction rate were considered and the activation parameters were determined.
- Abdrakhmanova,Kabal'nova,Rol'nik,Yagafarova,Shereshovets
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p. 1755 - 1760
(2007/10/03)
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- Conformational analysis of 2-halocyclohexanones: An NMR, theoretical and solvation study
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The conformational equilibria of 2-fluoro-, 2-chloro- and 2-iodo-cyclohexanone have been determined in various solvents by measurement of the J2-3 couplings. The observed couplings were analysed using theoretical and solvation calculations to give both the conformer energies in the solvents studied plus the vapour phase energies and the coupling constants in the distinct conformers. These plus previous results for the 2-bromo compound give the conformer energies and couplings of all the 2-halocyclohexanones. In the 2-fluoro compound the axial conformation is the most stable one in the vapour phase (Eeq - Eax = 0.45 kcal mol-1), while the equatorial conformer predominates in all the solvents studied. The other haloketones show similar behaviour, but the energy difference in the vapour phase is larger (Eeq - Eax = 1.05, 1.50 and 1.90 kcal mol-1, for the chloro, bromo and iodo compounds respectively) and the axial conformer is still the prevailing conformer in CCl4 solution for the chloro and bromo ketones and is the major form in all solvents for the iodo compound. The vapour state conformer energies for the fluoro and chloro compounds are in complete agreement with the ab initio calculated energies, but those for the bromo and iodo are not in such good agreement. Both the ab initio calculations and molecular mechanics are used to discuss the origins of the conformer energies. It is shown that the interaction between the C2 halogen and the C=O oxygen in the equatorial conformer is strongly attractive for fluorine, much less so for chlorine, ca. zero for bromine and repulsive for iodine. Comparison of the conformer couplings obtained here with calculated values show generally good agreement.
- Yoshinaga, Fabiana,Tormena, Claudio F.,Freitas, Matheus P.,Rittner, Roberto,Abraham, Raymond J.
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p. 1494 - 1498
(2007/10/03)
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- Palladium(II)-catalyzed oxidation of aldehydes and ketones. 1. Carbonylation of ketones with carbon monoxide catalyzed by palladium(II) chloride in methanol
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Unsubstituted or alkyl-substituted cyclic ketones react with PdCl2 in methanol under a CO atmosphere to give mainly acyclic diesters along with some acyclic chloro-substituted monoesters. The monosubstituted cyclic ketones, 2-hydroxy- and 2-methoxycyclohexanone, do not give ring cleavage but rather produce 2-(carbomethoxy)cyclohex-2-en-1-one. 13CO labeling experiments indicate one CO is inserted in forming the diester product so the second ester group must arise from the original ketone group. Two mechanisms are possible for the diester reaction. One involves initial Pd(II)-CO2CH3 insertion across the double bond of the enol form of the ketone while the second involves initial addition of Pd(II)-OCH3 followed by CO insertion into the new Pd(II) carbon bond formed. Pd(II) elimination and acid-catalyzed ring cleavage produce the second methyl ester group in both routes. The chloro-substituted monoester is formed by initial Pd(II)-Cl insertion across the double bond followed by the acid-catalyzed ring cleavage. The 2-(carbomethoxy)cyclohex-2-en-1-one must result from elimination of water or methanol from the α-ketoester product formed by the initial methoxycarbonylation of the enol form of the ketone. As expected, the acyclic ketone 2-decanone, formed methyl acetate and a mixture of methyl nonanoate and products.
- Hamed,El-Qisairi,Henry
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p. 180 - 185
(2007/10/03)
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- Addition of NOCl to cyclic vinylsilanes: An unexpected reversal of regiochemistry
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NOCl adds to cyclic vinylsilanes in a syn manner with NO+ bonding to the β-carbon and Cl- to the α-carbon, which is a reversal of the regiochemistry expected from the β-silicon effect. The adducts dimerize to a single diastereomer containing enantiomeric pairs and/or give secondary products on further reaction.
- Mallya, M. Narendra,Nagendrappa, Gopalpur,Shashidhara Prasad,Sridhar,Lokanath,Begum
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p. 2565 - 2568
(2007/10/03)
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- α-chlorination of ketones using p-toluenesulfonyl chloride
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Treatment of a variety of ketones with lithium diisopropylamide followed by p-toluenesulfonyl chloride gives α-chloroketones in good yields. In addition, a polymer bound tosyl chloride reagent has also been shown to effect this transformation.
- Brummond, Kay M.,Gesenberg, Kirsten D.
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p. 2231 - 2234
(2007/10/03)
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- Chlorination of substituted alkenes using trichloroisocyanuric acid
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This invention relates to a process for the selective monochlorination or dichlorination of certain substituted alkenes using trichloroisocyanuric acid. The chlorinated alkenes can be easily hydrolyzed to provide α-monochloroketones or α,α-dichloroketones with a high degree of selectivity. The resulting α-monochloroketones or α,α-dichloroketones have utility as fungicides or function as useful intermediates for fungicides.
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- α-chlorination of ketones with sodium chlorite, Mn(acac)3, and alumina in dichloromethane
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Chlorination of a variety of aliphatic, alicyclic, and aromatic ketones with a reagent combination of NaC1O2 and Mn(acac)3 catalyst can be readily performed in dichloromethane to afford α-chloroketones in good yield under mild and neutral conditions with the aid of chromatographic neutral alumina.
- Yakabe, Shigetaka,Hirano, Masao,Morimoto, Takashi
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p. 131 - 138
(2007/10/03)
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- New Enzyme Models of Chloroperoxidase: Improved Stability and Catalytic Efficiency of Iron Porphyrinates Containing a Thiolato Ligand
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The heme-thiolate protein chloroperoxidase (CPO) catalyzes the chlorination of activated C-H bonds. A reaction mechanism is proposed for this enzymatic transformation (Scheme 1), and a new iron(III) porphyrinate complex 13 is synthesized containing pentafluorophenyl groups at two meso-positions and a thiophenolato ligand coordinating to the Fe-atom (Schemes 2 and 3). Due to the presence of the electron-withdrawing substituents, the catalyst 13 is appreciably resistant to oxidants (HOCl) and chlorinates, e.g., monochlorodimedone (5), with turnover numbers up to 1530. The redox potential of 13, E0 = - 134 mV, and the Soret band (λmax 448 nm) of the CO adduct of the reduced state of 13 are close to the corresponding values of the enzyme CPO.
- Wagenknecht, Hans-Achim,Claude, Cécile,Woggon, Wolf-Dietrich
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p. 1506 - 1520
(2007/10/03)
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- Chlorination of substituted alkenes using trichloroisocyanuric acid
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This invention relates to a process for the selective monochlorination or dichlorination of certain substituted alkenes using trichloroisocyanuric acid. The chlorinated alkenes can be easily hydrolyzed to provide α-monochloroketones or α,α-dichloroketones with a high degree of selectivity. The resulting α-monochloroketones or α,α-dichloroketones have utility as fungicides or function as useful intermediates for fungicides.
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- A Convenient Halogenation Procedure for the Preparation of α-Halocarbonyl Compounds
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Except for substituted acetophenones (p-Y-C6H4COCH3, Y=H, Br, CH3O), simple ketones, α-ketoesters and 1,3-diketones reacted smoothly with a preformed homogeneous mixture of hydrochloric acid and potassium permanganate in acetonitrile to give moderate to good yields of the corresponding α-chlorocarbonyl compounds.Mixtures of α-chloro- and α,α-dichlorocarbonyl compounds were obtained for substituted acetophenones.Brominations proceeded similarly with higher yields when the hydrochloric acid was replaced with hydrobromic acid. - Key words: α-chlorocarbonyl compounds; α-bromocarbonyl compounds; potassium permanganate; chlorination; bromination.
- Cheng, Sheng-Fan,Lin, Ching-Shan,Liu, Lilian Kao
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p. 309 - 312
(2007/10/03)
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- Reactions of α-Chloro-β-oxoaldehydes with Dialkyl Phosphites
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Sodium dialkyl phosphites react with α-chloro- and α,α-dichloro-β-oxoaldehydes exclusively at the aldehyde carbonyl group with rupture of the C-CHO bond. The primary products are corresponding α-chloro- and α,α-dichloroenolates and unstable phosphinoylformaldehydes; the latter decompose into dialkyl hydrogen phosphites and carbon monoxide. Condensation products of α-halo-β-oxoaldehydes with dialkyl hydrogen phosphites in the presence of sodium hydride undergo similar transformations.
- Guseinov,Burangulova,Moskva
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p. 1564 - 1567
(2007/10/03)
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- Extending the haloform reaction to non-methyl ketones: Oxidative cleavage of cycloalkanones to dicarboxylic acids using sodium hypochlorite under phase transfer catalysis conditions
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Cyclohexanone is readily oxidized to adipic, α,α-dichloroadipic, glutaric and succinic acids by sodium hypochlorite under phase transfer conditions. The selectivity is highly dependent on the pH of the reacting system. A consecutive chlorination-hydrolysis mechanism is proposed in which only cyclohexanone is a reactive substrate leading in parallel to the melange of oxidized products. Cyclooctanone and cyclopentanone are similarly oxidized.
- Rothenberg, Gadi,Sasson, Yoel
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p. 13641 - 13648
(2007/10/03)
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- Reactions of α-Chloro- and α,α-dichloro-β-oxoaldehydes with Anionic Nucleophiles
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The reaction of α-chloro and α,α-dichloro-β-oxoaldehydes with anionic nucleophiles (NaOH, MeONa, PhONa, MeCOOK) proceeds mainly via haloform splitting with elimination of the formyl group; only with the most nucleophilic sodium methoxide, the reaction at the β-carbon atom partially occurs.The intermediate anions react with benzaldehyde to give difficulty accessible polyfunctional compounds.
- Guseinov, F. I.,Tagiev, S. Sh.,Moskva, V. V.
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- Ligand Exchange Reaction of Sulfoxides in Organic Synthesis: A New Synthesis of α-Chloroketones from Carbonyl Compounds with One-Carbon Homologation
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A new procedure for one-carbon homologation of carbonyl compounds to α-chloroketones is described.Addition of the carbanion of dichloromethyl phenyl sulfoxide with ketones and aldehydes gave the adducts, chloro alcohols, in good yields.Treatment of the chloro alcohols with EtMgBr or lithium diisopropylamide gave one-carbon homologated α-chloroketones via β-oxido carbenoid rearrangement in moderate to good yields.One-carbon homologation of esters to α-chloroketones was realized via the ligand exchange reaction of the sulfinyl group of α-chloro α-sulfinyl ketones, which were synthesized from methyl esters and chloromethyl phenyl sulfoxide, with EtMgBr.
- Satoh Tsuyoshi,Mizu, Yasuhiro,Kawashima, Taku,Yamakawa, Koji
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p. 703 - 710
(2007/10/02)
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- Reaction of epoxides with activated DMSO reagent. General method for synthesis of α-chlorocarbonyl compounds: Application in asymmetric synthesis of (3S)-2,3-oxidosqualene
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Reaction of a variety of epoxides with DMSO-Oxalyl chloride in the presence of a catalytic amount of methanol and a base was studied. Disubstituted epoxides gave α-chloroketones in high yields. Aliphatic terminal epoxide underwent opening reaction to provide α-chloroketone as a major product. Trisubstituted epoxides provided α-chloroketones as major products through the formation of more stable carbocation. In case of a homoallylic alcohol, enedione was obtained. The efficiency of the method was shown by applying it to the enantioselective synthesis of (3S)-2,3-oxidosqualene.
- Raina, Sushil,Singh, Vinod K.
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p. 2467 - 2476
(2007/10/02)
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- C-H bond activation by metal oxo species: Oxidation of cyclohexane by chromyl chloride
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Chromyl chloride (CrO2Cl2) reacts with cyclohexane solvent at 75 °C to give a dark precipitate along with chlorocyclohexane and a small amount of cyclohexene (in 10.0 and ca. 0.3% yields based on chromium). Hydrolysis of the precipitate, or treatment with a coordinating organic solvent such as acetonitrile, yields cyclohexanone (8.0%) and chlorocyclohexanone (2.5%). Spectroscopic studies of the precipitate indicate that the ketone products are present intact as σ-only ligands. Iodometric titrations of the complex show the average chromium oxidation state to be 3.41. The observed organic products account for only 26% of the chromium oxidizing equivalents used in the reaction; the remainder are most likely consumed in the formation of ring-opened products such as adipic acid. The three major organic products grow in concurrently during the course of the reaction and are not substantially oxidized further under the reaction conditions. Cyclohexene, however, is readily oxidized by CrO2Cl2 to give mostly ring-opened products with some 2-chlorocyclohexanone and cyclohexanone. The rate of reaction of CrO2Cl2 with cyclohexane, monitored via the optical absorbance of the CrO2Cl2 vapor above the solution, is first order in chromium; assuming first-order behavior in cyclohexane as well gives k = 1.07 × 10-5 M-1 s-1 at 75 °C, ΔH* = 26.6 (8) kcal/mol, and ΔS* = -5 (2) eu. Rates were reproducible with no sign of an induction period. Reaction in the presence of the radical trap CBrCl3 gave some bromocyclohexane. The data indicate that the reaction proceeds by initial hydrogen atom transfer from cyclohexane to CrO2Cl2. The cyclohexyl radical is rapidly trapped by oxidizing chromium species via one of three pathways: (i) chlorine atom abstraction, (ii) formation of a C-O bond, and (iii) transfer of a second hydrogen atom. The mass balance of the reaction and results from reactions of cyclohexane-d12 are consistent with this mechanism. The ability of CrO2Cl2 to abstract a hydrogen atom from cyclohexane is remarkable, as it is a closed-shell diamagnetic species, not a radical. It is proposed that the hydrogen atom abstracting ability derives from the ability of CrO2Cl2 to make a strong O-H bond by accepting a hydrogen atom. The strength of the analogous O-H bond made by permanganate can be calculated from a thermodynamic cycle to be 80 kcal/mol. Using this value for CrO2Cl2 provides both a qualitative and a quantitative understanding of the hydrogen atom transfer step. The implications of this perspective for transition metal mediated hydrogen atom transfer reactions are discussed.
- Cook, Gerald K.,Mayer, James M.
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p. 1855 - 1868
(2007/10/02)
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- A mild method for conversion of epoxides into α-chloro ketones
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Epoxides on treatment with DMSO, oxalyl chloride, and 10 mole % of methanol in the presence of triethylamine at -60°C are converted to α-chloro ketones in high yield.
- Raina,Bhuniya,Singh
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p. 6021 - 6022
(2007/10/02)
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- CHEMISTRY OF α-NITROEPOXIDES: SYNTHESIS OF USEFUL INTERMEDIATES VIA NUCLEOPHILIC RING OPENING OF α-NITROEPOXIDES
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Various α-nitroepoxides are converted into corresponding 1,2-diketones via two different ways of ring opening viz. with Pd(O) and with DMSO/BF3*EtO2 (or ClSiMe3).In addition to this, a variety of nucleophiles are reacted with α-nitrocyclopentene oxide 6 and α-nitrocyclohexene oxide 7 to form the corresponding α-substituted ketones which are useful intermediates in organic synthesis.Two of the products so obtained viz. 32 and 33 are also transformed further into optically active thialactones 38 and 39 respectively via baker's yeast reduction followed by lactonisation.
- Vankar, Yashwant D.,Shah, Kavita,Bawa, Anita,Singh, Surendra P.
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p. 8883 - 8906
(2007/10/02)
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- OXIDATION OF OLEFINS USING CHROMIC ANHYDRIDE-CHLOROTRIMETHYLSILANE. A CONVENIENT SYNTHESIS OF α-CHLORO KETONES.
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Disubstituted internal olefins are oxidized selectively to α-chloro ketones in excellent yields from the reaction with chromic anhydride-chlorotrimethylsilane in carbon tetrachloride.
- Lee, Jong Gun,Ha, Dong Soo
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p. 193 - 196
(2007/10/02)
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- THE CHLORINATION OF KETONES USING TRIMETHYLCHLOROSILANE AND DIMETHYLSULFOXIDE WITH BROMIDE ION CATALYSIS
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Chlorination using trimethylchlorosilane and dimerthylsulfoxide with bromide ion catalysis afforded almost quantitative yields for 1,3-diphenylacetone, benzoylacetone and propiophenone, and acceptable yields for acetophenone, acetylacetone and cyclohexanone.
- Fraser, Robert R.,Kong, Fanzuo
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p. 1071 - 1078
(2007/10/02)
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- OXYCHLORINATION OF ALKENES BY CHLOROCHROMATE REAGENTS: A FACILE PREPARATION OF α-CHLOROKETONES, AND COMPETITION BY SUBSTITUENT-DIRECTED OXIDATION.
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Cyanopyridinium chlorochromate effects a facile preparation of α-chloroketones from simple alkenes, cycloocta-1,5-diene and cyclododeca-1,5,9-triene; 1-methylcaclooct-4-en-1-ol undergoes oxidative cyclization.
- Guerrero, Angel F.,Kim, Ho-jin,Schlecht, Matthew F.
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p. 6707 - 6710
(2007/10/02)
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- sis- and trans-Dioxo complexes of chlororuthenium(VI)
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Dioxoruthenium(VI) complexes are prepared as the chloro derivatives O2RuCl42- and O2RuCl3- and isolated as the crystalline phosphonium and ammonium salts. Quantitative spectral studies (IR and UV-vis) establish the ready interconversion of the 6-coordinate O2RuCl42- to the 5-coordinate analogue with a dissociation constant K = 5.3 × 10-3 M for chloride loss in dichloromethane. The octahedral structure of O2RuCl42- is established by X-ray crystallography of the (Ph3P)2N+ salt to consist of trans-dioxo ligands with the asymmetric (A2u) stretching band at 830 cm-1 in the IR spectrum. [(Ph3P)2N+]2[O2RuCl 42-]: space group P1 (triclinic) with lattice constants a = 10.916 (2) A?, b = 12.378 (2) A?, c = 13.788 (2) A?, α = 105.65 (1)°, β = 93.16 (1)°, γ = 92.60 (1)°, and Z = 1. The coordinatively unsaturated trichloro derivative O2RuCl3- represents a rare example of a mononuclear dioxo complex whose solid-state structure is dependent on the counterion. Thus, the X-ray crystallography of the (Ph3P)2N+ salt establishes a trigonal-bipyramidal structure of O2RuCl3- with the cis-dioxo ligands absorbing as a single, strong IR band at 882 cm-1. [(Ph3P)2N+][O2RuCl3 -]: space group P21/n (monoclinic) with lattice constants a = 10.629 (4) A?, b = 15.636 (5) A?, c = 21.026 (7) A?, β = 99.60 (2)°, and Z = 4. The O2RuCl3- ion in the Ph4P+ salt is disordered between trigonal-bipyramidal and square-pyramidal geometries, which can be refined by using an occupancy ratio of 6:4 with R = 0.042 in the final refinement. The square-pyramidal component of O2RuCl3- is assigned with trans-dioxo ligands that account for the appearance of the unusual IR band at 891 cm-1 (together with the band at 878 cm-1) in crystalline [O2RuCl3-][Ph4P+] [tetragonal space group P4/n with lattice constants a = 12.672 (2) A?, c = 7.788 (2) A?, and Z = 2]. The (Ph3P)2N+, Ph4P+, Et4N+, and n-Bu4N+ salts of O2RuCl3- all show a single, sharp IR band at 885 cm-1 in solutions of dichloromethane or acetonitrile.
- Perrier,Kochi
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p. 4165 - 4173
(2008/10/08)
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- Mercury(II) Chloride-Iodine: A Useful Reagent for the Direct and Regiospecific Synthesis of α-Iodocarbonyl Compounds
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α-Iodoaldehydes and α-iodoketones are obtained by direct iodination of the corresponding carbonyl compounds with mercury(II) chloride-iodine in a regiospecific manner.
- Barluenga, Jose,Martinez-Gallo, Jose M.,Najera, Carmen,Yus, Miguel
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p. 678 - 680
(2007/10/02)
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- Ring Contraction of 2-Chlorocyclohexanone with Grignard Reagents
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The reaction of 2-chlorocyclohexanone with phenylmagnesium bromide in refluxing tetrahydrofuran unexpectedly afforded the ring-contracted product, cyclopentyl phenyl ketone, as the main product in moderate yield.The reactivities of several cyclic 2-haloketones were examined.Keywords - 2-chlorocyclohexanone; Grignard reaction; ring contraction; cyclopentyl phenyl ketone; solvent effect; THF; conformational isomer
- Hori, Mikio,Kataoka, Tadashi,Shimizu, Hiroshi,Imai, Eiji,Iwamura, Tatsunori,Maeda, Kaori
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p. 3599 - 3605
(2007/10/02)
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- REACTIONS OF ENOL SILYL ETHERS WITH N-HALOSUCCINIMIDE - A STEPWISE PROCESS.
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The N-chlorosuccinimide (NSC) reaction of a number of cyclic and acyclic trimethylsilyl enol ethers was investigated.Based on product analyses, the mechanism of the reaction is postulated to involve a step-wise process.
- Hambly, G. F.,Chan, T. H.
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p. 2563 - 2566
(2007/10/02)
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