- Photochemical Sandmeyer-type Halogenation of Arenediazonium Salts
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Trihalide salts were found to efficiently promote photochemical dediazotizing halogenations of diazonium salts. In contrast to classical Sandmeyer reactions, no metal catalysts are required to achieve high yields and outstanding selectivities for halogena
- Belitz, Florian,Goo?en, Lukas J.,Manu Martínez, ángel,Schmid, Rochus,Sivendran, Nardana,Sowa Prendes, Daniel
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supporting information
(2022/01/19)
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- Visible-Light-Photosensitized Aryl and Alkyl Decarboxylative Functionalization Reactions
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Despite significant progress in aliphatic decarboxylation, an efficient and general protocol for radical aromatic decarboxylation has lagged far behind. Herein, we describe a general strategy for rapid access to both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters followed by their successive use in divergent carbon–heteroatom and carbon–carbon bond-forming reactions. Identification of a suitable activator for carboxylic acids is the key to bypass a competing single-electron-transfer mechanism and “switch on” an energy-transfer-mediated homolysis of unsymmetrical σ-bonds for a concerted fragmentation/decarboxylation process.
- Patra, Tuhin,Mukherjee, Satobhisha,Ma, Jiajia,Strieth-Kalthoff, Felix,Glorius, Frank
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p. 10514 - 10520
(2019/07/12)
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- Ligand-free nickel-catalyzed Kumada couplings of aryl bromides with tert-butyl Grignard reagents
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A ligand-free nickel-catalyzed Kumada cross-coupling of aryl bromides and tert-butyl Grignard reagents led to the formation of a series of tert-butyl aryls in moderate to good yields, excellent tBu/iBu ratios, and good functional group compatibility. A radical coupling process is indicated and a mechanism with a Ni(I)-Ni(III) catalytic cycle is proposed.
- Wu, Zhenghan,Si, Tengda,Xu, Guangqing,Xu, Bin,Tang, Wenjun
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supporting information
p. 597 - 600
(2019/01/05)
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- Benzo polyaza and phosphole oxygen ligand and complex containing same, preparation method and application
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The invention discloses a benzo polyaza and phosphole oxygen ligand and a complex containing same, a preparation method and application. The invention provides a benzo polyaza and phosphole oxygen ligand as shown in formula I and a complex containing same. A complex of the benzo polyaza and phosphole oxygen ligand and a transition metal halide enables direct coupling of carbon-carbon bonds betweenbig steric hindrance alkyl and aryl; the reaction conditions are gentle; the catalyzing efficiency is high; the coupling reaction process of the carbon-carbon bonds between big steric hindrance alkyland aryl can be extremely simplified; the practicability is high; the reaction cost can be obviously decreased, and the reaction period is reduced; the complex is free from other side products without being required in the catalyzing process. The formula refers to the description.
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Paragraph 0152; 0153; 0154; 0155; 0156
(2019/01/16)
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- Iron(III)-mediated photocatalytic selective substitution of aryl bromine by chlorine with high chloride utilization efficiency
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An iron(III)-mediated photocatalytic method for the conversion of aryl, heteroaryl and polycyclic aromatic bromides to the corresponding chlorides with high selectivity has been achieved successfully. The mild reaction conditions and high chloride utilization efficiency promise a bright future for chlorination reactions. The Royal Society of Chemistry 2014.
- Wang, Ying,Li, Lina,Ji, Hongwei,Ma, Wanhong,Chen, Chuncheng,Zhao, Jincai
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supporting information
p. 2344 - 2346
(2014/03/21)
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- Halogen exchange via a halogenation of diaryliodonium salts with cuprous halide
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An efficient halogenation reaction has been developed with diaryliodonium salts and cuprous halides. Various diaryliodonium salts 1 could perform the reaction with readily available CuBr or CuCl in CH3CN at 80°C, assembling bromoarenes or chloroarenes in up to 92% yields. This provides us a method for the transformation from iodoarenes to other haloarenes.
- Li, Jian,Liu, Li,Ding, Dong,Sun, Jiang-Tao
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p. 541 - 548
(2014/01/06)
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- Microwave-assisted silica-supported aluminum chloride-catalyzed Friedel-Crafts alkylation
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Microwave irradiation is a popular method in organic synthesis to achieve high yields in shorter reaction times. This decreases total 'man-hours' in a synthetic setting. Another technique used in organic chemistry to decrease manual manipulations, is solid support reagents. The benefits of this approach is that upon completion of a reaction, a simple filtration can be performed which expedites the work-up and also produces less organic waste. Friedel-Crafts alkylation has been explored using microwave chemistry as well as with solid-supported reagents. In comparison with traditional heating, as well as with AlCl3, superior yields were observed with silica-gel bound aluminum chloride (Si-AlClx) when microwave irradiated for only 5 min.
- Zupp, Laurine R.,Campanella, Veronica L.,Rudzinski, Diandra M.,Beland, Franois,Priefer, Ronny
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p. 5343 - 5346
(2012/10/30)
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- Ultrasound assisted Friedel-Crafts acylation of aromatics using ferric sulphate as catalyst
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The use of ultrasound in the acylation reactions of various aromatics and polyaromatics with different acyl chlorides, in the presence of catalytic amount of ferric sulphate at room temperature, gives good yields of the respective ketones with a short reaction time. A facile and simple synthesis of various aromatic ketones using Friedel-Crafts acylation has been established from the corresponding acid chlorides and aromatic or polyaromatic compounds, respectively under mild reaction conditions with shorter reaction times (30-45 min) and in reasonable yields. This method offers the advantage of low cost and ease of purification of the products because of the small amount of ferric sulphate used in these reactions.
- Sridharan, Anandhi,Gopalakrishnan, Geetha
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experimental part
p. 1192 - 1195
(2011/10/18)
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- Metal-free chlorodeboronation of organotrifluoroborates
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A mild and metal-free method for the chlorodeboronation of organotrifluoroborates using trichloroisocyanuric acid (TCICA) was developed. Aryl-, heteroaryl-, alkenyl-, alkynyl-, and alkyltrifluoroborates were converted into the corresponding chlorinated products in good yields. This method proved to be tolerant of a broad range of functional groups.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 7195 - 7203
(2011/10/13)
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- Hypochlorite-induced ipso-substitution reactions of aromatic alcohols and related compounds
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Organic solvent extracts derived from aqueous hypochlorite/phase-transfer catalyst solutions induce rapid and efficient ipso substitution of aromatic carbinols and related substrates. The key parameter impacting rates and yields is pH of the original hypochlorite/phase-transfer catalyst component. Georg Thieme Verlag Stuttgart - New York.
- Carrillo, Hector V.,Rodriguez, Angelica Y.,Landolt, Robert G.,Hendrickson, William H.
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experimental part
p. 2069 - 2071
(2011/10/09)
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- Nickel-catalyzed Kumada cross-coupling reactions of tertiary alkylmagnesium halides and aryl bromides/triflates
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We report a Ni-catalyzed process for the cross-coupling of tertiary alkyl nucleophiles and aryl bromides. This process is extremely general for a wide range of electrophiles and generally occurs with a ratio of retention to isomerization >30:1. The same procedure also accommodates the use of aryl triflates, vinyl chlorides, and vinyl bromides as the electrophilic component.
- Joshi-Pangu, Amruta,Wang, Chao-Yuan,Biscoe, Mark R.
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supporting information; experimental part
p. 8478 - 8481
(2011/06/25)
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- Non-catalytic conversion of C-F bonds of benzotrifluorides to C-C bonds using organoaluminium reagents
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A facile method for the conversion of C-F bonds of benzotrifluorides to C-C bonds has been developed using aluminium reagents in the absence of catalysts.
- Terao, Jun,Nakamura, Misaki,Kambe, Nobuaki
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supporting information; experimental part
p. 6011 - 6013
(2010/11/16)
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- The conversion of phenols to the corresponding aryl halides under mild conditions
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Mild, novel procedures have been developed for the syntheses of aryl halides from the corresponding phenols in modest to good yields via boronate ester intermediates.
- Thompson, Alicia L. S.,Kabalka, George W.,Akula, Murthy R.,Huffman, John W.
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p. 547 - 550
(2007/10/03)
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- meta- rather than ortho-directed metalations: Buttressing effects prejudicing the proton abstraction from (2,6-dihalophenyl)silanes
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(2,6-Dichlorophenyl)trimethyl- and -triethylsilane exhibit untypical reactivity patterns toward strong bases. When treated at -100°C with lithium 2,2,6,6-tetramethylpiperidide, they give rise to two, with sec- or tert-butyllithium even three, different organometallic intermediates which can be intercepted with standard electrophiles. The trialkylsilyl group intervenes in two respects. Exerting steric pressure on the neighboring chlorine atoms, it facilitates the permutational displacement of one of them against lithium, a side reaction which occurs whenever alkyllithium compounds are employed. At the same time it impedes the attack of hydrogen atoms by the base in the immediate vicinity of the halogens due to relay transmission of steric hindrance. As a consequence, deprotonation occurs preferentially or exclusively at the 5-("meta") rather than the 4-("ortho")position. 4-Lithiated species, generated as by-products or separately by permutational halogen/metal interconversion, eliminate lithium chloride at -75°C to set free didehydrobenzenes ("arynes") which are trapped by their aryllithium precursors. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Heiss, Christophe,Cottet, Fabrice,Schlosser, Manfred
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p. 5236 - 5241
(2007/10/03)
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- PROCESS FOR HALOGENATION OF BENZENE AND BENZENE DERIVATIVES
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In a process of halogenation of benzene or benzene derivatives, di-substituted halobenzene derivatives having para-aromatic compounds or tri-substituted halobenzene derivatives having 1,2,4-substituted aromatic compounds are selectively produced. In halogenation of benzene or benzene derivatives, a fluorine-containing zeolite catalyst such as L-type zeolite, or a zeolite catalyst having the crystal size of at most 100 nm is used. The reaction is preferably effected in the presence of a solvent, and the solvent is preferably a halogenated compound.
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Page/Page column 19; 20
(2008/06/13)
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- Electrophilic aromatic chlorination and haloperoxidation of chloride catalyzed by polyfluorinated alcohols: A new manifestation of template catalysis
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We have demonstrated that a polyfluorinated alcohol, 2,2,2-trifluoroethanol, solvent enables haloperoxidase type activity and the oxychlorination of arenes (benzene and its alkylated derivatives) without a metal catalyst. The polyfluorinated alcohol has a dual function; it catalyzes electrophilic chlorination of less reactive arenes by several orders of magnitude and oxidation of chloride at lower H+ concentrations. DFT calculations show that a complementary charge template in the transition state explains the catalysis of the electrophilic chlorination. Copyright
- Ben-Daniel, Revital,De Visser, Samuel P.,Shaik, Sason,Neumann, Ronny
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p. 12116 - 12117
(2007/10/03)
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- Facile synthesis of pivalophenones by an ultrasound assisted iodine catalysed Friedel-Crafts acylation reaction
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The use of ultrasound in the acylation reactions of various aromatics and heterocyclics with pivaloyl chloride in the presence of catalytic amount of iodine, without any added solvent and at room temperature, gives excellent yields of the respective pivalophenones in a short reaction time.
- Gopalakrishnan, Geetha,Anandhi,Narasimhan
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p. 1197 - 1198
(2007/10/03)
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- A facile synthesis of pivalophenones by ultrasound assisted AlCl3 catalysed Friedel-Crafts reaction
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Pivalophenones have been prepared by the acylation reaction of various aromatic and heterocyclic compounds with pivaloyl chloride using AlCl3 as catalyst under sonochemical conditions in a short reaction time and in reasonable yields.
- Gopalakrishnan, Geetha,Anandhi,Narasimhan
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p. 1194 - 1196
(2007/10/03)
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- Studies on the synthesis of chiral 2-(p.chlorophenyl)-3-methylbutanoic acid, a key-precursor of Fenvalerate, by hydrocarbonylation reactions
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The preparation of racemic 2-(p.chlorophenyl)-3-methylbutanoic acid (2), a building block for (S,S)-Fenvalerate (an important broad spectrum insecticide), was effected by rhodium catalyzed hydroformylation of 2-methyl-1 -(p.chlorophenyl) propene (4) in the presence of excess of triphenylphosphine to inhibit substrate isomerization followed by mild oxidation of the resulting aldehyde 6; an overall yield of 88% was reached. Olefin 4 exhibits a very low tendency to undergo both hydrocarboethoxylation and hydrocarboxylation in the presence of palladium complexes as catalysts. Enantioselective hydrocarbonylation reactions carried out on olefin 4 afford unsatisfactory chemical and optical yields of the optically active ester 5 or acid 2. Springer-Verlag 1996.
- Botteghi, Carlo,Bona, Denis Dalla,Paganelli, Stefano,Marchetti, Mauro,Sechi, Barbara
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p. 101 - 107
(2007/10/03)
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- Hydrocarbons and chloroaromatics from anilines and n-butyl nitrite
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A single reagent, i.e. n-butyl nitrite, can be used to oxidize an aromatic amine, or the corresponding N-methylene derivative, to a diazo compound followed by its subsequent reduction to hydrocarbon in a single batch.Alternatively, a chloro derivative can be obtained if carbon tetrachloride is used as the solvent.The reactions appear to be general and complete product identification was accomplished.
- Giumanini, Angelo G.,Verardo, Giancarlo,Gorassini, Fausto,Strazzolini, Paolo
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p. 311 - 316
(2007/10/02)
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- Initiation of Cationic Polymerization of Cyclic Ethers by Redox Radical-Chain Reactions of Onium Salts
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Redox radical-chain reactions of diaryliodonium halides (Ar2I(+)X(-)) with tetrahydrofuran (THF) and 1,3-dioxolane to give arenes (ArH) and iodoarenes (ArI) are reported.When the reactions are initiated by irradiation at 313 nm, the quantum yield for the formation of iodoarene is substantially greater than 1 (Φ ca. 2-20).Nonphotochemical radical initiators give the same reaction, showing that the photochemical step is simply an initiation step.The key propagation step in these reactions is a single-electron reduction of the onium salts by ether-derived radicals.The photoinitiated reaction with THF follows zero-order kinetics, showing that termination does not compete with electron transfer.In addition, the same nonphotochemical conditions that give radical-chain reduction of the diaryliodonium halides give rapid cationic polymerization of the ethers when the iodonium hexafluorophosphates are used.These observations establish the connection between the redox chemistry of the iodonium salt and the cationic polymerization of the eters.The polymerization of THF by iodonium salt in the presence of free radicals is accelerated by the addition of trimethyl phosphite (TMP).Furthermore, triarylsulfonium salts will initiate polymerization of THF in the presence of TMP and radical sources.Therefore, redox-chain reduction of these onium salts by TMP can also initiate cationic polymerization of the cyclic ethers.
- Kampmeier, J. A.,Nalli, Thomas W.
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p. 1381 - 1388
(2007/10/02)
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- Versatility of Zeolites as Catalysts for Ring or Side-Chain Aromatic Chlorinations by Sulfuryl Chloride
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Zeolites catalyze chlorination of aromatics by sulfuryl chloride SO2Cl2.It is possible by an appropriate choice of the catalyst to effect at will, with very high selectivity, either the ring or the side-chain chlorination.Zeolite ZF520 is the choice catalyst for the former, because of its high Broensted acidity.Zeolite NaX (13X) is a fine catalyst for the latter, free-radical chlorination; the reaction is best effected in the presence of a light source; the catalyst can be reused many times with no loss in activity.Both reaction modes, the ionic (ring chlorination)and the radical (side-chain substitution), are likely to occur outside of the channel network in the microporous solid.The effects of various experimental factors - such as the nature of the solvent, the reaction time and temperature, the Broensted acidity of the solid support, the presence of radical inhibitors, and the quantity of catalysts - were investigated.The procedures resulting from this study are very easy to implement in practice and are quite effective.
- Delaude, Lionel,Laszlo, Pierre
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p. 5260 - 5269
(2007/10/02)
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- Halogenation Using Quaternary Ammonium Polyhalides. XIX. Aromatic Chlorination of Arenes with Benzyltrimethylammonium Tetrachloroiodate
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The reaction of arenes with a calculated amount of benzyltrimethylammonium tetrachloroiodate in acetic acid at room temperature or at 70 deg C gave nuclear chloro-substituted arenes in fairly good yields.
- Kajigaeshi, Shoji,Ueda, Yasuhiro,Fujisaki, Shizuo,Kakinami, Takaaki
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p. 2096 - 2098
(2007/10/02)
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- 2-aryl-ethyl ether derivatives and insecticidal and acaricidal agents containing said derivatives
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The present invention relates to 2-arylethyl ether or thioether derivatives represented by the following general formula [I]: STR1 wherein Ar stands for an aryl group, R1 stands for straight or branched chain alkyl group of 1 to 6 carbons, R2 stands for a hydrogen atom, or a methyl or ethyl group, R3 stands for a halogen atom, or a methyl or methoxyl group, R4 stands for a hydrogen or halogen atom, or a lower alkyl or lower alkoxy group, and n is an integer of 1 or 2 with the proviso that when n is 2, the groups R4 may be the same or different, and Y stands for an oxygen or sulfur atom, and also to processes for the preparation of these ethers or thioethers and a use of these ethers or thioethers. These compounds of the present invention have excellent insecticidal and acaricidal activities while the toxicity of these compounds are very low.
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- New Reagent Systems for Electrophilic Chlorination of Aromatic Compounds: Organic Chlorine-Containing Compounds in the Presence of Silica
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In the presence of silica, a number of chlorine-containing organic compounds, such as N,N-dichlorourethane, dichloramine-T, and t-butyl hypochlorite, become active electrophilic reagents capable of controlled monochlorination of aromatic compounds under mild conditions; for example, t-butyl hypochlorite/silica chlorinates alkylbenzenes, naphthalene, and anisole readily at 25 deg C; N,N-dichlorourethane/silica chlorinates benzene within 2 days 50 deg C.
- Smith, Keith,Butters, Michael,Paget, Walter E.,Nay, Barry
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p. 1155 - 1156
(2007/10/02)
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- Highly para-Selective Mono-Chlorination of Aromatic Compounds Under Mild Conditions by t-Butyl Hypochlorite in the Presence of Zeolites
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t-Butyl hypochlorite supported on H(1+), Na(1+) faujasite X (zeolite X) produces para-selective monochlorination of alkyl-, phenyl-, and halobenzenes under mild conditions; for example, chlorobenzene in acetonitrile (at 40 deg C) is chlorinated in high yield of isolated product (92percent) to give dichlorobenzene with an isomer ratio 97percent para/3percent ortho.
- Smith, Keith,Butters, Michael,Nay, Barry
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p. 1157 - 1158
(2007/10/02)
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- 2-Arylpropyl ether or thioether derivatives and insecticidal and acaricidal agents containing said derivatives
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The present invention relates to 2-arylpropyl ether or thioether derivatives represented by the following general formula [I]: STR1 wherein Ar stands for an aryl group, R stands for a methyl or ethyl group, Y stands for an oxygen or sulfur atom, and B stands for a group represented by the following formula [II]: STR2 or the following general formula [III]: STR3 wherein Z stands for an oxygen or sulfur atom or a carbonyl or methylene group, R1 stands for a hydrogen or halogen atom or a lower alkyl group or a lower alkoxy group, and n is an integer of from 1 to 5 with the proviso that when n is 2 or more, the groups R1 may be the same or different, and also to processes for the preparation or these ethers of thioethers and a use of these ethers or thioethers. These compounds of the present invention have excellent insecticidal and acaricidal activities while the toxicity of these compounds are very low.
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- Complexation of Arenediazonium Ions by Macrocyclic Multidentate Compounds
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A kinetic technique is utilized to determine the relative complexing abilities of 40 macrocyclic multidentate compounds for p-tert-butylbenzenediazonium tetrafluoroborate in 1,2-dichloroethane.The influence of ligand structure variations, such as ring size, nature of heteroatoms, and substituent effects, upon complexation efficiency is assessed.Maximum complexation is achieved with a 21-membered polyether macrocycle.
- Bartsch, Richard A.,Juri, Pedro N.
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p. 1011 - 1014
(2007/10/02)
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- REGIOSELECTIVE PARA-CHLORINATION OF ALKYLBENZENES ON CHEMICALLY-MODIFIED SILICA SURFACES
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Chlorination of alkylbenzenes was carried out with chlorine in carbon tetrachloride in the presence of chemically-modified silica catalysts.The para/ortho ratios were remarkably higher than those obtained in the FeCl3-catalyzed chlorination. t-Butylbenzene was chlorinated at para-position almost exclusively.The catalyst could be reused several times.
- Konishi, Hisatoshi,Yokota, Kiyoshi,Ichihashi, Yuji,Okano, Tamon,Kiji, Jitsuo
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p. 1423 - 1426
(2007/10/02)
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