- Perdeuteration of Deactivated Aryl Halides by H/D Exchange under Superelectrophile Catalysis
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Superelectrophilic silylium/arenium ions are shown to be highly effective H/D exchange promoters for the exhaustive deuteration of electron-deficient aryl halides. Several of the resulting perdeuterated aryl halides have been previously inaccessible with existing deuterium-labeling procedures. Using inexpensive C6D6as the deuterium source, excellent degrees of deuterium incorporation were achieved under ambient reaction conditions. Importantly, the perdeuteration remains unaffected on multigram scale, even at a reduced catalyst loading of 0.1 mol %. By this method, otherwise expensive or noncommercially available NMR solvents such as 1,2-dichloro- and 1,2-difluorobenzene can be prepared.
- He, Tao,Klare, Hendrik F. T.,Oestreich, Martin
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supporting information
p. 4734 - 4738
(2022/03/27)
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- Catalytic deuteration of C(sp2)-H bonds of substituted (Hetero)arenes in a Pt(II) CNN-pincer complex/2,2,2Trifluoroethanol-d1 system: Effect of substituents on the reaction rate and selectivity
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Thirty four (hetero)arene derivatives have been tested in catalytic H/D exchange reactions involving their C(sp2)- H bonds and 2,2,2-trifluoroethanol-d1 (TFE-d1) in the presence of the homogeneous Pt(II) complex 1 supported by a sulfonated CNN-pincer ligand at 80 °C. The 18 substrates, including one pharmaceutical (naproxen), that are stable in the presence of 1 and are active in the H/D exchange reaction have been characterized by their position-specific extent of deuteration and, in a number of cases, the reaction kinetic selectivity. For the most reactive substrates the extent of deuteration approaches the expected statistical distribution of the exchangeable H and D atoms: e.g., 67-69% for phenol after 23 h and 88% for indole β-CH bonds after 45 min. For a few substrates (N,N-dimethylaniline, indole, nitrobenzene) the H/D exchange is highly position selective. No satisfactory correlation was found between the position-specific (meta, para) H/D exchange rate constants for X-monosubstituted benzenes and Hammett σX constants. This observation was proposed to be related to the concerted nature of the CH bond activation, the rate-determining CH bond oxidative addition at a Pt(II) center. A novel scale of Hammett σMX constants was introduced to characterize the reactivity of C(sp2)-H bonds in transition-metal-mediated reactions. The experimentally determined position-specific Gibbs energies of activation of the H/D exchange in substituted benzenes (meta and para positions) as well as in thiophene (α and β positions) were matched satisfactorily using DFT calculations.
- Kramer, Morgan,Watts, David,Vedernikov, Andrei N.
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supporting information
p. 4102 - 4114
(2020/11/30)
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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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- 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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supporting information
p. 10514 - 10520
(2019/07/12)
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- Pd(II)-Catalyzed Synthesis of Alkylidene Phthalides via a Decarbonylative Annulation Reaction
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An unprecedented Pd(II)-catalyzed decarbonylative C-H/C-C activation and annulation reaction, which proceeds via intramolecular cyclization, is reported. This reaction of hydroxynaphthoquinones with disubstituted alkynes provides good yields of substituted alkylidene phthalides, which are the key intermediates for the synthesis of bioactive natural products.
- Borthakur, Somadrita,Baruah, Swagata,Sarma, Bipul,Gogoi, Sanjib
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supporting information
p. 2768 - 2771
(2019/04/16)
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- Ruthenium(II)-Catalyzed Synthesis of Spirobenzofuranones by a Decarbonylative Annulation Reaction
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The first decarbonylative insertion of an alkyne through C?H/C?C activation of six-membered compounds is reported. The Ru-catalyzed reaction of 3-hydroxy-2-phenyl-chromones with alkynes works most efficiently in the presence of the ligand PPh3 to provide spiro-indenebenzofuranones. Unlike previously reported metal-catalyzed decarbonylative annulation reactions, in the present decarbonylative annulation reaction, the annulation occurs before extrusion of carbon monoxide.
- Kaishap, Partha P.,Duarah, Gauri,Sarma, Bipul,Chetia, Dipak,Gogoi, Sanjib
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supporting information
p. 456 - 460
(2018/02/21)
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- Directed: Ortho C-H borylation catalyzed using Cp?Rh(iii)-NHC complexes
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Cp?Rh(NHC) complexes with bulky chiral bidentate NHC-carboxylate ligands were efficiently synthesized and fully characterized including solid-state structures. These unprecedented rhodium(iii) complexes demonstrated high selectivity in pyridine-directed ortho-C-H borylation of arenes under mild conditions.
- Thongpaen, Jompol,Schmid, Thibault E.,Toupet, Loic,Dorcet, Vincent,Mauduit, Marc,Baslé, Olivier
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supporting information
p. 8202 - 8205
(2018/07/29)
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- A stable isotope labeled 2 - isopropyl thioxanthone and its synthesis method
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The invention relates to stable isotopic labeled 2-isopropylthioxanthone and a synthetic method thereof. The stable isotopic labeled 2-isopropylthioxanthone is 2-isopropylthioxanthone labeled by D or 13C. The synthetic method comprises the following steps of using benzene and acetone which are labeled by stable isotopic D or 13C as raw materials; reacting the benzene and the acetone with magnesium to obtain Grignard reagent after benzene bromination; performing reduction and hydroxide radical bromination on the acetone to obtain 2-bromic propane; performing Grignard reaction to obtain isopropyl benzene; reacting the isopropyl benzene with dithio-salicylic acid; and synthesizing to obtain the 2-isopropylthioxanthone labeled by the stable isotopic D or 13C. Compared with the prior art, the stable isotopic labeled 2-isopropylthioxanthone has the advantages that a process route is simple, the 2-isopropylthioxanthone is easy to synthesize, products are easy to separate and purify, the chemical purity of the products is above 99.0%, isotope abundance is above 98.0% atom, requirements of trace detection in the field of food safety can be met fully, and economical efficiency and using value are excellent.
- -
-
Paragraph 0051; 0072; 00732; 0080; 0081; 0199
(2018/04/21)
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- Cp?CoIII-Catalyzed syn-Selective C-H Hydroarylation of Alkynes Using Benzamides: An Approach Toward Highly Conjugated Organic Frameworks
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Hydroarylation of internal alkynes by cost-effective CoIII-catalysis, directed by N-tert-butyl amides, is achieved to avail mono- or dihydroarylated amide products selectively in an atom and step economic way. Several important functional groups were tolerated under the reaction conditions, and syn-hydroarylation products were exclusively isolated. Notably, a 4-fold C-H hydroarylation provided a highly conjugated organic framework in one step. Kinetic study with extensive deuterium labeling experiments were performed to support the proposed mechanism.
- Bera, Sourav Sekhar,Debbarma, Suvankar,Ghosh, Avick Kumar,Chand, Santanu,Maji, Modhu Sudan
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supporting information
p. 420 - 430
(2017/04/26)
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- Synthesis of isotopically labelled 2-isopropylthioxanthone from 2,2′-dithiosalicylic acid and deuterium cumene
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Two efficient synthetic routes of stable deuterium labelled 2-isopropylthioxanthone were presented with 98.1% and 98.8% isotopic abundance in acceptable yields and excellent chemical purities. Their structures and the isotope-abundance were confirmed according to proton nuclear magnetic resonance and liquid chromatography–mass spectrometry.
- Fang, Chao,Yang, Weicheng,Yang, Chao,Wang, Haoran,Sun, Kai,Luo, Yong
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p. 313 - 316
(2016/07/11)
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- Palladium-catalyzed trifluoromethylthiolation of aryl C-H bonds
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A method for monotrifluoromethylthiolation of arenes via palladium-catalyzed directed C-H bond activation was described. The reaction was compatible with a variety of functional groups. Initial mechanistic studies disclosed that the turnover limiting step of the catalytic cycle did not involve C-H activation.
- Xu, Chunfa,Shen, Qilong
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supporting information
p. 2046 - 2049
(2014/05/06)
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- Ruthenium-catalyzed direct C-H amidation of arenes: A mechanistic study
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We report mechanistic studies of C-H activitation/amidation reactions using azides as the amino source catalyzed by [RuCl2(p-cymene)] 2. We have achieved two intermediates in the catalytic cycle (C 5H4NC6H4)Ru(p-cymene)Cl and (C 5H4NC6H4)NArRu(p-cymene)Cl (Ar = NO2C6H4SO2). Furthermore, the process from (C5H4NC6H4)Ru(p-cymene) Cl to (C5H4NC6H4)NArRu(p-cymene)Cl was monitored by 19F NMR and a ruthenium-imido species was proposed to explain the formation of the azacyclopropane analogue.
- Zhang, Lu,Li, Lian-Hua,Wang, Yu-Qi,Yang, Yan-Fang,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 1905 - 1908
(2014/05/20)
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- An efficient Rh/O2 catalytic system for oxidative C-H activation/annulation: Evidence for Rh(I) to Rh(III) oxidation by molecular oxygen
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A novel and efficient Rh/O2 catalytic system has been developed and shown to catalyze highly efficient oxidative C-H activation/annulation reactions, producing a broad range of isoquinolinium salts with high turnover numbers (up to 740). Mechanistic studies provided strong evidence of facile oxidation of Rh(I) to Rh(III) by molecular oxygen facilitated by acid.
- Zhang, Guoying,Yang, Lei,Wang, Yanyu,Xie, Yinjun,Huang, Hanmin
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supporting information
p. 8850 - 8853
(2013/07/25)
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- Synthesis of all-deuterated tris(2-phenylpyridine)iridium for highly stable electrophosphorescence: The "deuterium effect"
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Device stability and life-time rank the key issues for PhOLEDs. We synthesized deuterated Ir(ppy)3-D24. A device based on it has a current density twenty times higher than and a life-time six times longer than devices based on Ir(ppy)3. The more stable C-D bond is found to be the main contributing factor, called the "deuterium effect".
- Wang, Ping,Wang, Fei-Fei,Chen, Yi,Niu, Qiang,Lu, Lei,Wang, Hong-Ming,Gao, Xi-Cun,Wei, Bin,Wu, Hong-Wei,Cai, Xin,Zou, De-Chun
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p. 4821 - 4825
(2013/09/23)
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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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- Ruthenium-catalyzed hydroarylation of methylenecyclopropanes through C-H bond cleavage: Scope and mechanism
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Intermolecular hydroarylation reactions of highly strained methylenecyclopropanes 2-phenylmethylenecyclopropane (1), 2,2- diphenylmethylenecyclopropane (2), methylenespiropentane (3), bicyclopropylidene (4), (dicyclopropylmethylene)cyclopropane (5), and benzhydrylidenecyclopropane (6) through C-H bond functionalization of 2-phenylpyridine (7 a) and other arenes with directing groups were studied. The reaction was very sensitive to the substitution on the methylenecyclopropanes. Although these transformations involved (cyclopropylcarbinyl)-metal intermediates, substrates 1 and 4 furnished anti-Markovnikov hydroarylation products with complete conservation of all cyclopropane rings in 11-93 % yield, whereas starting materials 3 and 5 were inert toward hydroarylation. Methylenecyclopropane 6 formed the products of formal hydroarylation reactions of the longest distal C-C bond in the methylenecyclopropane moiety in high yield, and hydrocarbon 2 afforded mixtures of hydroarylated products in low yields with a predominance of compounds that retained the cyclopropane unit. As byproducts, Diels-Alder cycloadducts and self-reorganization products were obtained in several cases from substrates 1-3 and 5. The structures of the most important new products have been unambiguously determined by X-ray diffraction analyses. On the basis of the results of hydroarylation experiments with isotopically labeled 7 a-[D5], a plausible mechanistic rationale and a catalytic cycle for these unusual ruthenium-catalyzed hydroarylation reactions have been proposed. Arene-tethered ruthenium-phosphane complex 53, either isolated from the reaction mixture or independently prepared, did not show any catalytic activity. Copyright
- Ackermann, Lutz,Kozhushkov, Sergei I.,Yufit, Dmitry S.
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supporting information
p. 12068 - 12077
(2012/10/29)
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- Synthesis of fluorenone derivatives through Pd-catalyzed dehydrogenative cyclization
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Palladium-catalyzed dual C-H functionalization of benzophenones to form fluorenones by oxidative dehydrogenative cyclization is reported. This method provides a concise and effective route toward the synthesis of fluorenone derivatives, which shows outstanding functional group compatibility.
- Li, Hu,Zhu, Ru-Yi,Shi, Wen-Juan,He, Ke-Han,Shi, Zhang-Jie
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supporting information
p. 4850 - 4853,4
(2012/12/12)
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- Gold-catalyzed halogenation of aromatics by N-halosuccinimides
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(Chemical Equation Presented) Golden bromination: A highly efficient and mild AuCl3-catalyzed bromination of aromatic rings with Nbromosuccinimide (NBS) has been developed. This method works with a low catalyst loading (down to 0.01 mol %) and can be combined with transition metal catalyzed transformations to deliver various aryl products.
- Mo, Fanyang,Yan, Jerry Mingtao,Qiu, Di,Li, Fei,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 2028 - 2032
(2010/06/17)
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- Ruthenium-catalyzed hydroarylations of methylenecyclopropanes: Mild C-H bond functionalizations with conservation of cyclopropane rings
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(Chemical Equation Presented) Ring conservation was observed in the first catalytic intermolecular hydroarylation of methylenecyclopropanes via C-H bond functionalization, a remarkable reactivity mode for a transformation proceeding through (cyclopropylcarbinyl)metal intermediates.
- Kozhushkov, Sergei I.,Yufit, Dmitry S.,Ackermann, Lutz
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supporting information; experimental part
p. 3409 - 3412
(2009/04/21)
-
- Resonance Raman investigation on the interaction of styrene and 4-methyl styrene oligomers on sulphated titanium oxide
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In order to understand the nature of the interaction that gives rise to the yellow-orange colour observed when styrene or 4-methyl styrene are put in contact with sulphated TiO2, the resonance Raman spectra of such systems, including deuterated styrene (ring-deuterated d5 and perdeuterated d8) and allylbenzene were investigated. In all cases a substantial enhancement of the ring v(CC) stretching mode was observed. A charge transfer process involving a transition from the ring π-electrons to the empty d-π orbitals of titanium was ascribed responsible for the absorption in the visible. Two types of resonance Raman spectra were observed depending on the excitation wavelength, which can be explained by the presence of two kinds of oligomers, saturated and unsaturated, on the surface of the oxide with the former giving rise to a Raman enhancement at a higher excitation energy.
- Noda,Sala
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p. 145 - 155
(2007/10/03)
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- Vibrational spectra and normal coordinate analysis of p-bis(dimethyl-hydroxy-silil)benzene-d0 and -d4
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The i.r. and Raman spectra of p-bis(dimethyl-hydroxy-silil)tetradeuterobenzene have been obtained and compared with data of the corresponding normal compound.Complete normal mode calculations of both -d0 and -d4 derivatives have been carried out using a set of valence force constants transferred from suitable molecules and refined to account for the observed i.r. and Raman data.Results of a model calculation, in which substituents are considered as point masses, are also discussed in order to provide a convenient starting point to study the chain conformation of a polymer obtained through polycondensation of the investigated molecule.
- Sbrana, G.,Neto, N.,Muniz-Miranda, M.,Nocentini, M.
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p. 295 - 304
(2007/10/02)
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- Skeletal Rearrangements on Chemical Ionization of Dibenzyl Ether and Derivatives
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Protonated molecular ions of dibenzyl ether, formed by chemical ionization using hydrogen and isobutane as reagent gases, undergo skeletal rearrangements to lose water and formaldehyde, both in the ion source and the flight path.The rearrangements have been elucidated by deuterium labelling and chemical substitution.The water lost contains the reagent proton and an aromatic hydrogen atom, and the aromatic hydrogen atoms have been shown to be mobile prior to the reaction.It is proposed that the skeletal rearrangement for water loss is initiated by protonation on the other oxygen atom, followed by benzyl migration.The formaldehyde loss contains benzylic hydrogen atoms exclusively, and it is proposed that the skeletal rearrangement is preceded by hydrogen rearrangement of an oxygen protonated molecular ion to a ring protonated molecular ion.Daughter ion structures are supported by comparisons of their collision induced dissociation spectra with those of isomeric ions prepared by alternative routes.
- Kingston, Eric E.,Shannon, James S.,Diakiw, Vladimir,Lacey, Michael J.
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p. 428 - 440
(2007/10/02)
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- Relaxation in an A2 coupled spin system dissolved in a perdeuterated liquid crystal: The intermolecular dipolar random field cross relaxation term
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A perdeuterated nematic liquid crystal N-(p-ethoxybenzylidene)-p-n-butylaniline (EBBA-d23, 98percent deuterium) was synthesized to study relaxation of small molecules dissolved in anisotropic solvents.Proton spin-lattice relaxation in the coupled A2 spin system of methylene chloride (CH2Cl2) was studied using both perhydro and perdeutero EBBA as the solvent.The relaxation was modeled as intramolecular dipole-dipole interactions plus other mechanisms that were treated collectively as fluctuating external random magnetic fields.Comparison of relaxation in EBBA and EBBA-d23 allowed the first experimental measurement of the correlation coefficient between external random fields at the two protons due to dipolar interactions of the methylene protons with the protons or deuterons of the solvent (78percent correlated).The selective nuclear Overhauser effect was also studied.
- Courtieu, J.,Jullien, J.,Lai, Nguyen Thoi,Guillois, A.,Gonord, P.,et al.
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p. 953 - 959
(2007/10/02)
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