- Electrolysis of trichloromethylated organic compounds under aerobic conditions catalyzed by the B12 model complex for ester and amide formation
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The electrolysis of benzotrichloride at -0.9 V vs. Ag/AgCl in the presence of the B12 model complex, heptamethyl cobyrinate perchlorate, in ethanol under aerobic conditions using an undivided cell equipped with a platinum mesh cathode and a zinc plate anode produced ethylbenzoate in 56% yield with 92% selectivity. The corresponding esters were obtained when the electrolysis was carried out in various alcohols such as methanol, n-propanol, and i-propanol. Benzoyl chloride was detected by GC-MS during the electrolysis as an intermediate for the ester formation. When the electrolysis was carried out under anaerobic conditions, partially dechlorinated products, 1,1,2,2-tetrachloro-1,2-diphenylethane and 1,2-dichlorostilibenes (E and Z forms), were obtained instead of an ester. ESR spin-trapping experiments using 5,5,-dimethylpyrroline N-oxide (DMPO) revealed that the corresponding oxygen-centered radical and carbon-centered radical were steadily generated during the electrolyses under aerobic and anaerobic conditions, respectively. Applications of the aerobic electrolysis to various organic halides, such as substituted benzotrichlorides, are described. Furthermore, the formation of amides with moderate yields by the aerobic electrolysis of benzotrichloride catalyzed by the B12 model complex in the presence of amines in acetonitrile is reported.
- Shimakoshi, Hisashi,Luo, Zhongli,Inaba, Takuya,Hisaeda, Yoshio
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supporting information
p. 10173 - 10180
(2016/07/06)
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- Oxygen-Controlled Catalysis by Vitamin B12-TiO2: Formation of Esters and Amides from Trichlorinated Organic Compounds by Photoirradiation
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An oxygen switch in catalysis of the cobalamin derivative (B12)-TiO2 hybrid catalyst for the dechlorination of trichlorinated organic compounds has been developed. The covalently bound B12 on the TiO2 surface transformed trichlorinated organic compounds into an ester and amide by UV light irradiation under mild conditions (in air at room temperature), while dichlorostilbenes (E and Z forms) were formed in nitrogen from benzotrichloride. A benzoyl chloride was formed as an intermediate of the ester and amide, which was detected by GC-MS. The substrate scope of the synthetic strategy is demonstrated with a range of various trichlorinated organic compounds. A photo-duet reaction utilizing the hole and conduction band electron of TiO2 in B12-TiO2 for the amide formation was also developed.
- Shimakoshi, Hisashi,Hisaeda, Yoshio
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p. 15439 - 15443
(2016/01/26)
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- Chromium-carbyne complexes: Intermediates for organic synthesis
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(Chemical Equation Presented) On the same route: Chromium-carbyne complexes are readily prepared by treatment of 1,1,1-trichloromethyl reagents with chromium(II) chloride. They serve as intermediates in the selective formation of a wide variety of products, such as alkynes, alkenes, β-hydroxy ketones, aldehydes, allylic alcohols, and allenes (see scheme, E = electrophile).
- Bejot, Romain,He, Anyu,Falck, John R.,Mioskowski, Charles
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p. 1719 - 1722
(2008/02/13)
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- Tandem Pd/C-catalyzed reductive coupling and dehalogenation of benzylic halides
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High-yield reductive homocoupling of benzotrichloride and benzal chloride followed by consecutive reductive dechlorination to 1,2-dichlorostilbene and stilbene is effected in the presence of sodium formate as the reducing agent and Pd/C catalysts. Copyright Taylor & Francis, Inc.
- Joshi, Ashutosh V.,Baidossi, Mubeen,Taha, Nimer,Mukhopadhyay, Sudip,Sasson, Yoel
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p. 2715 - 2722
(2007/10/03)
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- Inter- and innermolecular reactions of chloro(phenyl)carbene
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Supramolecular photolyses of 3-chloro-3-phenyl-3H-diazirine (8) were performed within cyclodextrin (CyD) hosts to determine whether these toroidal inclusion compounds could alter the reactivity of the ensuing carbene reaction intermediate, chloro(phenyl)carbene (9). Remarkably, no intramolecular products stemming from carbene 9 could be detected. Instead, modified CyDs were formed via so-called innermolecular reactions. Hence, diazirine 8 was photolyzed in various conventional solvents to gauge the intermolecular reactivity of carbene 9. Relevant results were used to rationalize the CyD innermolecular reaction products.
- Rosenberg, Murray G.,Brinker, Udo H.
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p. 4819 - 4832
(2007/10/03)
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- Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCI (HBr) Acetonitrile Reagent
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Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields.
- Liu, Lilian Kao,Lin, Ching-Shan
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- A laser flash photolysis study of carbonyl ylides of arylchlorocarbenes: Kinetics and reversibility of the formation, cyclization, and cycloaddition
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Carbonyl ylides formed from (p-nitrophenyl)chlorocarbene or phenylchlorocarbene and acetone or benzaldehyde have been studied by laser flash photolysis. The rate constants for the formation of these ylides, for their cyclization to oxiranes, and for some addition reactions have been measured. Electron-withdrawing substituents on the carbene increase the rate of ylide formation and decrease the rate of cyclization. The trapping of carbonyl ylide and para-substituted benzaldehydes gave a Hammett's ρ value equal to +1.0. The dual role of benzaldehyde, first as a constituent of the ylide and second as a trapping agent, has been demonstrated. Kinetic analysis indicates that an equilibrium exists between the phenylchlorocarbene, the acetone, and the corresponding ylide, with an equilibrium constant around 0.27 M-1 at 300 K.
- Bonneau,Liu
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p. 744 - 747
(2007/10/02)
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- Reductive Coupling by Chromium(0) - (Bibenzyl)- and (Stilbene)tricarbonylchromium(0) Complexes by a One-Pot Reaction from Benzylic Halides
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Reaction of Cr(CO)3(NH3)3 with benzylic mono-, di-, and trihalides leads to the formation of 1,2-diarylethanes, -ethenes, and diphenylethyne in satisfactory yields.Di(halomethyl)benzene derivatives yield product mixtures containing both reduction products and coupling products.With a higher excess in chromium(0), under otherwise unchanged reaction conditions, the corresponding (arene)tricarbonylchromium(0) complexes of the coupling products are formed in a one-pot reaction from the benzylic halides.
- Wey, Hans G.,Butenschoen, Holger
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- A PHENYLCARBENE TRANSFER SYSTEM
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Treatment of (α,α-dichlorobenzyl)trimethylsilane with potassium fluoride/18-crown-6 ether/diglyme transfers phenylchlorocarbene to a number of carbenophiles at room temperature.
- Cunico, Robert F.,Chu, Kuang S.
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p. 271 - 278
(2007/10/02)
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- Electrochemical Reduction of Trichloromethylbenzene
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The electrochemical reduction of trichloromethylbenzene (benzotrichloride) has been investegated by cyclic voltammetry, pulse polarography, and preparative scale reductions.Depending on conditions, benzal chloride, benzyl chloride, 1,2-diphenyl-1,1,2,2-tetrachloroethane, Z- and E-1,2-dichloro-1,2-diphenylethylene, and diphenylacetylene may be obtained.At a mercury electrode at the potential of the prewave the main products are 1,2 -diphenyl-1,1,2,2-terachloroethane (ca.60 percent) and diphenylacetylene (ca.25 percent); at a more negative potential benzal chloride is the main product with low yields of dimerized products. 1,2-Diphenyl-1,1,2,2-tetrachloroethane is reduced to a mixture of Z- and E-1,2,-dichloro-1,2-diphenylethene which in turn is reduced to diphenylacetylene.
- Gisselbrecht, Jean-Paul,Lund, Henning
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p. 773 - 778
(2007/10/02)
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- Electrochemical Reduction of Trichloromethylbenzene II Reduction in the Presence of Electrophiles
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Electrochemical reduction of trichloromethylbenzene at a mercury electrode in DMF/TBABF4 in the presence of acetic anhydride gives 1,2-diacetoxy-1-phenylpropene as major product; minor products are dichloromethylbenzene and dimerized products.During the reduction 1,1-dichloro-1-phenyl-2-propane and 2-acetoxy-1-chloro-1-phenylpropene can be detected.With sodium perchlorate as supporting electrolyte 1-chloro-1-phenyl-2-propanone and 1-acetoxy-1-phenyl-2-propanone are formed; these products are also formed during the reduction of benzal chloride in the presence of acetic anhydride.Reductive carboxylation of trichloromethylbenzene gives 2,2-dichloro-2-phenylacetic acid.
- Gisselbrecht, Jean-Paul,Lund, Henning
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p. 823 - 828
(2007/10/02)
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- Highly Reactive Metallic Nickel: Reductive Homocoupling Reagent for Benzylic Mono- and Polyhalides
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Metallic nickel, prepared by the reduction of nickel halides with lithium in glyme using naphthalene as an electron carrier, was found to be a useful reagent for the homocoupling of benzylic mono- and polyhalides.Benzyl halides reacted with metallic nickel at room temperature to give the corresponding 1,2-diarylethanes in good to high yields and functional groups on the aromatic ring such as methoxy, chloro, bromo, nitro, cyano, and alkoxycarbonyl groups were not affected under the conditions employed.Benzylic monohalides (1-(chloromethyl)- or 2-(bromomethyl)naphthalene, chlorodiphenylmethane, and 9-bromofluorene) also underwent coupling reactions with metallic nickel at room temperature to give the corresponding ethane derivatives.On the other hand, benzylic di- and trihalides such as α,α-dibromotoluene and α,α,α-trichlorotoluene yielded mixtures of cis and trans isomers of substituted ethenes.The intermediate of the reaction, benzylnickel complex, was trapped with electron deficient olefins such as methyl acrylate and acrylonitrile.
- Inaba, Shin-ichi,Matsumoto, Hideyuki,Rieke, Reuben D.
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p. 2093 - 2098
(2007/10/02)
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- CONVERSION OF DISILANES TO FUNCTIONAL MONOSILANES. XIII. THE PALLADIUM CATALYZED REDUCTIVE COUPLING OF BENZYLIDENE DICHLORIDES AND BENZYLIDYNE TRICHLORIDES USING DISILANES AS REDUCING AGENTS.
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The reaction of benzylidene dichlorides or benzylidene trichlorides with 1,2-dichloro-1,1,2,2-tetramethyl-disilane or hexamethyldisilane proceeded smoothly in the presence of a catalytic amount of Pd(PPh//3)//4 to give (E)-stilbenes or (E)- and (Z)- alpha beta -dichlorostilbenes in high yields, respectively. Also, in the presence of the palladium (0) catalyst, alpha , alpha -dichlorobenzyltrimethylsilanes reacted with hexamethyldisilane yielding (E)- alpha , beta -bis(trimethylsilyl)stilbenes in quantitative yield.
- Matsumoto,Arai,Takahashi,Ashizawa,Nakano,Nagai
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p. 3009 - 3014
(2007/10/02)
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- HAMMETT-KORRELATION VON PHENYLCHLORCARBEN - TEMPERATURABHAENGIGKEIT, SELEKTIVITAET
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Phenylchlorcarbene 2 reacts as an electrophile as deduced from a Hammett-plot; the ρ-values in the addition reaction with styrenes are clearly temperature dependent.
- Brueck, Wolfgang,Duerr, Heinz
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p. 2175 - 2178
(2007/10/02)
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- METALLIC NICKEL AS A REAGENT FOR THE COUPLING OF AROMATIC BENZYLIC HALIDES
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The oxidative addition of aromatic and benzylic halides to activated metallic nickel occured under mild conditions to give the corresponding dehalogenative coupled products in good yields.
- Inaba, Shin-ichi,Matsumoto, Hideyuki,Rieke, Reuben D.
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p. 4215 - 4216
(2007/10/02)
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- Vinyl Cation Intermediates in Electrophilic Additions to Triple Bonds. 1. Chlorination of Arylacetylenes
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The products of ionic addition of chlorine to phenylacetylene, β-methylphenylacetylene, 4-methylphenylacetylene, β-ethylphenylacetylene, and tolan have been investigated in anhydrous acetic acid.The major products are the α,β-dichlorostyrenes arising from simple 1,2-addition, but significant yields of solvent-incorporated products are also found.In some cases significant yields of β-chlorophenylacetylenes are found, presumably arising from an addition-elimination process.No products arising from addition of 2 mol of Cl2 were observed.The reactions are clearlynonstereospecific and show only weak stereoselectivity varying from predominant syn to predominant anti addition.However, the reactions are all completely regiospecific in the Markovnikov sense.In the presence of low concentrations of added salts such as lithium chloride, acetate, and perchlorate, the product distribution and stereochemistry are hardly affected.Only at high concentrations of these salts is there any significant change in product distribution.The second-order rates of addition have been measured for five additional phenyl-substituted compounds.The seven ring-substituted phenylacetylenes show an excellent correlation with ?+, giving a large negative ρ value (-4.19).The effects of β-substitution on the rate of chlorination are very small.The results are interpreted in terms of a simple Ad-E2 process, in which the rate-determining transition state is an open vinyl-cation-like species, with most of the positive charge being developed at Cα.The subsequent product-determining intermediate is considered to be a tight ion pair between an open α-phenylvinyl cation and a chloride counterion.This ion pair can react by ion-pair collapse, solvent attack, or internal proton elimination.Activation parameters determined for three of the above compounds show that the higher rates of chlorination (over bromination) of the acetylene system are due almost entirely to lower Δ H(excit.) values.
- Yates, Keith,Go, T. Andrew
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p. 2377 - 2384
(2007/10/02)
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- Peroxide-induced α-Elimination of Organic Halides from Organotellurium(IV) Halides
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Treatment of organotellurium(IV) halides with t-butyl hydroperoxide in 1,4-dioxan, acetic acid, or acetonitrile affords the corresponding organic halides in good to moderate yields presumably as the result of a 1,2-halogen shift.
- Uemura, Sakae,Fukuzawa, Shin-ichi
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p. 1033 - 1034
(2007/10/02)
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