- Addition of Electron-Rich Aromatics to Azafullerenium Carbocation. A Stepwise Electrophilic Substitution Mechanism
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(Matrix presented) The reaction between the C59N+ carbocation and the electron-rich aromatic compounds toluene and anisole has been mechanistically studied. The measured intermolecular kinetic isotope effects are consistent with an electrophilic aromatic substitution mechanism in which the arenium cation is formed by electrophilic attack of C 59N+ on the aromatic ring in the first step of the reaction, followed by hydrogen abstraction in a rate-determining second step.
- Vougioukalakis, Georgios C.,Chronakis, Nikos,Orfanopoulos, Michael
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Read Online
- Palladium-Catalyzed Nondirected Late-Stage C-H Deuteration of Arenes
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We describe a palladium-catalyzed nondirected late-stage deuteration of arenes. Key aspects include the use of D2O as a convenient and easily available deuterium source and the discovery of highly active N,N-bidentate ligands containing an N-acylsulfonamide group. The reported protocol enables high degrees of deuterium incorporation via a reversible C-H activation step and features extraordinary functional group tolerance, allowing for the deuteration of complex substrates. This is exemplified by the late-stage isotopic labeling of various pharmaceutically relevant motifs and related scaffolds. We expect that this method, among other applications, will prove useful as a tool in drug development processes and for mechanistic studies.
- Farizyan, Mirxan,Mondal, Arup,Mal, Sourjya,Deufel, Fritz,Van Gemmeren, Manuel
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supporting information
p. 16370 - 16376
(2021/10/21)
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- Entry to 1,2,3,4-Tetrasubstituted Arenes through Addressing the " Meta Constraint" in the Palladium/Norbornene Catalysis
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Arenes with four different contiguous substituents, i.e. 1,2,3,4-tetrasubstituted arenes, are commonly found in bioactive compounds, but they are nontrivial to access via conventional methods. Through addressing the "meta constraint" in the palladium/norbornene (Pd/NBE) cooperative catalysis, which is the difficulty of tolerating a sizable meta substituent in aryl halide substrates, here a modular and regioselective approach is realized for preparing 1,2,3,4-tetrasubstituted arenes. One key is the use of a C2-amide-substituted NBE, and a combined experimental and computational study reveals its role in promoting the NBE insertion and the ortho C-H metalation steps. The scope is broad: A variety of electrophiles and nucleophiles could be introduced to the ortho and ipso positions, respectively, with 1,4-disubstituted aryl halides, leading to diverse unsymmetrical contiguous tetrasubstituted arenes. Application of this approach has been demonstrated in streamlined syntheses of several bioactive compounds.
- Dong, Guangbin,Liu, Peng,Wang, Jianchun,Xu, Xiaolong,Zhou, Yun
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supporting information
p. 3050 - 3059
(2020/03/10)
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- Deuterium modified C-glycoside derivatives of benzyl-4-chlorophenyl
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The invention belongs to the technical field of medicine, and in particular, relates to deuterium modified C-glycoside derivatives of benzyl-4-chlorophenyl or pharmaceutically acceptable salts thereof, a method for preparing the compounds, pharmaceutical
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Paragraph 0072; 0074-0076
(2019/12/25)
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- Catalytic arene H/D exchange with novel rhodium and iridium complexes
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Three novel pendant acetate complexes, [Rh(bdmpza)Cl3] -M+, [Rh(bdmpza)Cl2(py)], and [Ir(bdmpza)Cl3]-M+ (bdmpza = bis(3,5-dimethylpyrazol-1-yl) acetate, M+ = Li+, Na +), were synthesized. Abstraction of halide from these complexes with silver salts yielded species capable of C-H activation of arenes. The catalytic H/D exchange reaction between benzene and trifluoroacetic acid-d was optimized, and these conditions were used to evaluate H/D exchange in other arenes. Branched alkyl substituents in alkyl aromatics showed an affinity toward deuterium exchange in the β-alkyl position only. DFT calculations were performed to determine the mechanism of H/D exchange.
- Rhinehart, Jennifer L.,Manbeck, Kimberly A.,Buzak, Sara K.,Lippa, Geoffrey M.,Brennessel, William W.,Goldberg, Karen I.,Jones, William D.
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experimental part
p. 1943 - 1952
(2012/04/23)
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- SUBSTITUTED UREAS
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Disclosed herein are urea-based 5-HT receptor modulators, pharmaceutically acceptable salts and prodrugs thereof, the chemical synthesis thereof, and medical use of such compounds for the treatment and/or management of 5-HT receptor-mediated disorders.
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Page/Page column 28
(2008/12/08)
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- trans-resveratrol-d4, a molecular tracer of the wild-type phytoalexin; synthesis and spectroscopic properties
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A convenient, six-step synthesis of the so far unknown trans-resveratrol- d4, (E)-3′,4,5′-trihydroxy-2,3,5,6-tetradeuterostilbene, starting from commercially available phenol-d6, with an overall yield of 25%, is described. The final
- Gabriele, Bartolo,Benabdelkamel, Hicham,Plastina, Pierluigi,Fazio, Alessia,Sindona, Giovanni,Di Donna, Leonardo
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experimental part
p. 2953 - 2956
(2009/04/07)
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- Synthesis of [2,3,3,2'3',5',6' -2H7]-L-tyrosine from phenol-d6
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An enantioselective synthesis of [2,3,3,2'3',5',6'-2H7]-L-tyrosine is described. Z-3-(4-acetoxy-2,3,5,6-2H4-phenyl)-3-2H-2-acetylamino acrylic acid was prepared in five steps from phenol-d6. Chiral reduction of the olefin followed by removal of the acetate protecting groups furnished the d7-amino acid in high ee.
- Kendall, John T.
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p. 917 - 924
(2007/10/03)
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- A Linear Free Energy Relationship for an Equilibrium Isotope Effect
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The solution electron affinities of a series of monosubstituted phenyl-d5 benzenes relative to their perprotiated analogues were measured via electron paramagnetic resonance studies.The equilibrium constant for the electron transfer X-C6H5.- + X-C6D5 X-C6H5 + X-C6D5.-, where X = H, C6D5, CN, NO2, OCH3, tert-butyl, was found to be less than unity for all cases.However, this equilibrium constant is closer to unity for those systems where the substituent is electron withdrawing in nature, and it deviates further from unity for those systems that have an electron-donating group as the substituent.A linear free energy relationship was found, and the positive ρ value (0.34) is presumably due to the fact that there is a smaller excess charge and spin density from the antibonding electron in the area of the molecule where isotopic substitution takes place, for those systems where the ? value of the substituent is positive.
- Stevenson, Gerald R.,Wehrmann, Glenn C.,Reiter, Richard C.
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p. 901 - 905
(2007/10/02)
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- Electroreductive Dehalogenation of Chlorinated Aromatic Ethers. Unexpected Electrogenerated Base Catalyzed Reactions
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The electroreductive dehalogenation of several mono- and polychlorinated aromatic ethers that serve as models of dioxins has been studied.The dechlorination was achieved by a simple constant-current electrolysis using a lead cathode in dimethylformamide.It was shown that 2,4,6-trichloroanisole undergoes successive dechlorination and the chlorine in the 2-position is selectively eliminated.Competitive reactions and cyclic voltammetric measurements suggested the increasing reactivity order of mono- di- trichloride for the reductive dechlorination.Use of allyl 2-chloro phenyl ether as a probe for radical cyclization indicated that free radical intermediates are of little importance.Thus, incipient radicals are immediately reduced to anionic intermediates.The electrolyses in the presence of deuterium oxide revealed proton sources for the present dechlorination.In these attempts, novel phenomena due to electrogenerated base (EGB) were found: di- and trichlorides underwent an unexpected overincorporation of deuterium in their dechlorinated products; a selective formation of Z-enol ethers from the allylic ethers was encountered.The mechanistic features of the present electroreductive dechlorination are discussed.
- Kimura, Makoto,Miyahara, Hiroyoshi,Moritani, Noriyuki,Sawaki, Yasuhiko
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p. 3897 - 3902
(2007/10/02)
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- Stable Negative-Ion Isomers in the Gas Phase. C7H7O- Species
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The C7H7O- ions formed by deprotonation of benzyl alcohol, norbornadien-7-ol and quadricyclin-7-ol are discrete species which all fragment by competitive losses of H., H2, CH2O and C6H6 on collisional activation.The isomeric ion from
- Eichinger, Peter C. H.,Bowie, John H.,Hayes, Roger N.
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p. 865 - 874
(2007/10/02)
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- Synthesis of i)(PR3)2H3>i)(Pri2PCH2CH2PPri2)H3>, and Analogues and Their Ability to catalyse the Photoinduced Hydrogen-Deuterium Exchange of Carbon-Hydrogen Bonds; Crystal Structure of i)(η-Cl)2>2>
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Hydrochlorination of 5-C5H4CMe2)> gives i)(μ-Cl)2>2> for which the crystal structure has been determined.This compound is a precursor to i)(PR3)2Cl2> (R3 = Me3 or Me2Ph), i)(Pri2PCH2CH2PPri2)2Cl2>, i)(Me2PCH2CH2PMe2)2>, i)(Me2PCH2CH2PMe2)2H>, i)-trans-(PMe3)2Cl-cis-H2>, i)(PR3)2H3>, and i)(PMe3)2O>.Photolysis of in deuteriobenzene together with the substrates (CH3)2O, CH3CO2CH3, toluene, mesitylene, ferrocene, bis(η-toluene)tungsten, and other organometallic compounds causes hydrogen-deuterium exchange between the C6D6 and some of all of the substrate hydrogens.The i)(PR3)2H3> derivatives are less active catalysts towards photoinduced H-D exchange reactions.
- Grebenik, Peter D.,Green, Malcolm L. H.,Izquierdo, Alejandro,Mtetwa, Victor S. B.,Prout, K.
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