- Trityl tetraphenylborate as a reagent in organometallic chemistry
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Trityl tetraphenylborate, prepared from trityl triflate and sodium tetraphenylborate, is shown to be a useful hydride and methyl anion abstraction reagent for organometallic compounds.It reacts with (η5-C5Me5)(PMe3)2RuMe to give the fulvene com
- Straus, Daniel A.,Zhang, Cheng,Tilley, T. Don
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- The stable pentamethylcyclopentadienyl cation
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More than 100 years after the cyclopentadienyl anion appeared in the literature, the first cyclopentadienyl cation, the pentamethyl derivative C5Me5+, has now been prepared in a single step as the tetrakis(pentafluoropheny
- Lambert, Joseph B.,Lin, Lijun,Rassolov, Vitaly
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- Synthesis and characterization of a gold vinylidene complex lacking π-conjugated heteroatoms
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Abstract Hydride abstraction from the gold (disilyl)ethylacetylide complex [(P)Au{η1-C≡CSi(Me)2CH2CH2SiMe2H}] (P=P(tBu)2o-biphenyl) with triphenylcarbenium tetrakis(pentafluorophenyl)borate at -20 °C formed the cationic gold (β,β-disilyl)vinylidene complex [(P)Au=C=CSi(Me)2CH2CH2Si(Me)2]+B(C6F5)4- with ≥90% selectivity. 29Si NMR analysis of this complex pointed to delocalization of positive charge onto both the β-silyl groups and the (P)Au fragment. The C1 and C2 carbon atoms of the vinylidene complex underwent facile interconversion (ΔG≠=9.7 kcal mol-1), presumably via the gold π-disilacyclohexyne intermediate [(P)Au{η2-C≡CSi(Me)2CH2CH2Si(Me)2}]+B(C6F5)4-. Good as gold: Cationic gold (β,β-disilyl)vinylidene complex 1 was generated by addition of a pendant silylium ion to the C≡C bond of a gold acetylide complex (see scheme, P=PtBu2(o-biphenyl)). The vinylidene C1 and C2 atoms of 1 undergo facile interconversion, presumably via a π-disilacyclohexyne intermediate. 29Si NMR analysis of 1 indicates delocalization of positive charge onto both the β-silyl groups and the (P)Au fragment.
- Harris, Robert J.,Widenhoefer, Ross A.
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- N-Heterocyclic Phosphenium Dihalido-Aurates: On the Borderline between Classical Coordination Compounds and Ion Pairs
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2-Bromo- and 2-chloro-1,3,2-diazaphospholenes react with (tht)AuCl to afford isolable N-heterocyclic phosphenium (NHP) dihalido-aurates, which were characterized by analytical and spectroscopic data and in one case by a single-crystal X-ray diffraction study. The T-shaped metal coordination sphere found in the crystal consists of a pseudo-linear AuX2 unit that is perturbed by a weakly bound NHP unit. DFT studies indicate that the subunits interact mainly through electrostatic and dispersion forces, with negligible covalent contributions, and that the phosphenium dibromido-aurate is slightly more stable than an isomeric complex with an intact bromophosphane ligand. NMR studies reveal that the NHP-AuX2 pairs persist in solution but are kinetically labile and readily undergo halide scrambling. The hydride/fluoride exchange reaction between a secondary phosphane-AuCl complex and [Ph3C][BF4] implies that a gold complex with an intact 2-halogeno-1,3,2-diazaphospholene ligand may be more stable than its phosphenium dihalido-aurate isomer when covalent P–X bonding contributions are strengthened.
- Nickolaus, Jan,Schlindwein, Simon H.,Nieger, Martin,Gudat, Dietrich
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- STOICHIOMETRIC HYDRODEHALOGENATION AND FORMYLATION OF ORGANIC HALIDES USING TETRACARBONYL COBALTATE(-I)
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Methanolic solutions of tetracarbonyl cobaltate(-I) in the presence of an acid bring about replacement of organic halogens by hydrogen or the formyl group.In general, hydrogenolysis is the main (often the only) reaction, but formylation becomes significant with aliphatic and benzyl halides.
- Ungvary, Ferenc,Marko, Laszlo
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- Stable silylnitrilium ions
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Trityl tetrakis[bis(3,5-trifluoromethyl)phenyl]borate, Ph3C+B[3,5-(CF3)2C6H 3]4-, abstracts hydride from hydridosilanes, producing Ph3CH. Use of a weakly co
- Bahr, Steven R.,Boudjouk, Philip
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- 'Redox-switch' catalysis of C-C bond formation with H2: One-electron reduction of the trityl cation
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Different products are formed from the electron transfer reaction between the ruthenium hydride 1 and the trityl cation when 1 is employed as a 'redox-switch' catalyst or as stoichiometric reducing agent. In the first case 1 converts H2 into a one-electron reducing agent for C-C bond formation, thus yielding the product known as Gomberg's dimer. In contrast, only triphenylmethane is produced in the stoichiometric reactions, by an electron-transfer/hydride-transfer mechanism.
- Hembre,McQueen
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- Superacid-catalyzed condensation of benzaldehyde with benzene. Study of protonated benzaldehydes and the role of superelectrophilic activation
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Under superacid conditions benzaldehyde reacts readily with benzene to give triphenylmethane in high yield. Experimental evidence supports the involvement of diprotonated benzaldehyde in the reaction. Ab initio calculations at the correlated MP2/6-31G* le
- Olah, George A.,Rasul, Golam,York, Chentao,Prakash, G. K. Surya
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- Protonation of a Cobalt Phenylazopyridine Complex at the Ligand Yields a Proton, Hydride, and Hydrogen Atom Transfer Reagent
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Protonation of the Co(I) phenylazopyridine (azpy) complex [CpCo(azpy)] 2 occurs at the azo nitrogen of the 2-phenylazopyridine ligand to generate the cationic Co(I) complex [CpCo(azpyH)]+ 3 with no change in oxidation state at Co. The N-H bond of 3 exhibits diverse hydrogen transfer reactivity, as studies with a variety of organic acceptors demonstrate that 3 can act as a proton, hydrogen atom, and hydride donor. The thermodynamics of all three cleavage modes for the N-H bond (i.e., proton, hydride, and hydrogen atom) were examined both experimentally and computationally. The N-H bond of 3 exhibits a pKa of 12.1, a hydricity of ΔG°H- = 89 kcal/mol, and a bond dissociation free energy (BDFE) of ΔG°H? = 68 kcal/mol in CD3CN. Hydride transfer from 3 to the trityl cation (ΔG°H- = 99 kcal/mol) is exergonic but takes several hours to reach completion, indicating that 3 is a relatively poor hydride donor, both kinetically and thermodynamically. Hydrogen atom transfer from 3 to 2,6-di-tert-butyl-4-(4′-nitrophenyl)phenoxyl radical (tBu2NPArO·, ΔG°H? = 77.8 kca/mol) occurs rapidly, illustrating the competence of 3 as a hydrogen atom donor.
- McLoughlin, Elizabeth A.,Waldie, Kate M.,Ramakrishnan, Srinivasan,Waymouth, Robert M.
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- Trapping of an NiII Sulfide by a CoI Fulvene Complex
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The reaction of [LtBuNiII(SCPh3)] (LtBu = {(2,6-iPr2C6H3)NC(tBu)}2CH) with Cp*2Co yields a NiI cobaltocenium thiolate complex, [LtBuNiI(SCH2Me4C5)Co(Cp*)] (1), along with HCPh3. Formation of this complex is proposed to occur via the reaction of a transient NiII sulfide, [Cp*2Co][LtBuNiII(S)], with a CoI fulvene complex, [CoCp*(C5Me4CH2)]. The latter complex is formed in situ by reaction of [Cp*2Co]+ with [CPh3]?. Control experiments, as well as cyclic voltammetry measurements of 1, are used to support the proposed mechanism.
- Hartmann, Nathaniel J.,Wu, Guang,Hayton, Trevor W.
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- CATALYTIC ACTIVITY OF TRIVALENT LANTHANIDE SALTS IN THE ALKYLATION REACTIONS OF AROMATIC HYDROCARBONS BY THE ACTION OF A MIXTURE OF AN ACYL HALIDE AND BENZALDEHYDE
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A study was carried out on the electrophilic substitution reactions of benzene and toluene by the action of a mixture of an acyl halide and benzaldehyde in the presence of trivalent lanthanide salts LnCl3, where Ln = Ce, Dy, Er, Sm, Yb, and Yb(O3SCF3)3, a
- Davydov, D. V.,Vinogradov, S. A.,Beletskaya, I. P.
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- Substituent effects on the reaction of trityl chlorides with Grignard reagents
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The result of the substitution of trityl chlorides with Grignard reagents was found to be highly dependent on the solvent and the nature of the substituents on the trityl group. In THF, electron donating substituents were found to give high yields of Grig
- Oyler,Ketz,Glass
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- An Intramolecular NADH Model Containing an Activating Acidic Group
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The acridan derivative (1) as a model for NADH reduces alcohols and imines without any external activation by acids whereas similar models such as (2) with equimolar amounts of acetic acid in neutral solvents did not effect any reduction; an analogy with
- Singh, Serjinder,Nagrath, Sarita,Chanana, Minakshi
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- Hydride reduction of o-(fluorosilyl)benzodifluorides for subsequent C-F transformations
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An efficient method for sequential C-F transformations of o-hydrosilyl-substituted benzotrifluorides is disclosed. A key to the success is hydride reduction of o-fluorosilyl-substituted difluoromethylenes prepared by a single C-F transformation of o-hydrosilyl-substituted benzotrifluorides. We succeeded in further C-F transformations via hydride abstraction of the resulting o-hydrosilyl group, enabling us to synthesize a wide variety of organofluorine compounds.
- Hosoya, Takamitsu,Idogawa, Rika,Kim, Youngchan,Kobayashi, Akihiro,Shimomori, Ken,Yoshida, Suguru
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supporting information
p. 3521 - 3524
(2022/03/31)
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- Deoxygenation of tertiary and secondary alcohols with sodium borohydride, trimethylsilyl chloride, and potassium iodide in acetonitrile
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The deoxygenation of tertiary and secondary alcohols to give the corresponding alkanes is conventionally performed using an organosilane and a strong acid. In this study, a deoxygenation method was developed for tertiary and secondary alcohols, using trimethylsilane and trimethylsilyl iodide generated in situ from sodium borohydride and trimethylsilyl chloride, and trimethylsilyl chloride and potassium iodide, respectively. With our method, tertiary and secondary alcohols, which provided stable carbocations, were converted into the corresponding alkanes. This paper also presents the optimization of the reaction conditions, the reaction mechanism, as well as the scope and limitations of the method.
- Kato, Yuichi,Inoue, Tomoka,Furuyama, Yuuki,Ohgane, Kenji,Sadaie, Mahito,Kuramochi, Kouji
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supporting information
(2021/11/16)
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- A Mild, General, Metal-Free Method for Desulfurization of Thiols and Disulfides Induced by Visible-Light
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A visible-light-induced metal-free desulfurization method for thiols and disulfides has been explored. This radical desulfurization features mild conditions, robustness, and excellent functionality compatibility. It was successfully applied not only to the desulfurization of small molecules, but also to peptides.
- Qiu, Wenting,Shi, Shuai,Li, Ruining,Lin, Xianfeng,Rao, Liangming,Sun, Zhankui
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supporting information
p. 1255 - 1258
(2021/05/05)
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- Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki-Miyaura Reactions of Diarylmethyl Esters
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The synthesis of triarylmethanes via Pd-catalyzed Suzuki-Miyaura reactions between diarylmethyl 2,3,4,5,6-pentafluorobenzoates and aryl boronic acids is described. The system operates under mild conditions and has a broad substrate scope, including the coupling of diphenylmethanol derivatives that do not contain extended aromatic substituents. This is significant as these substrates, which result in the types of triarylmethane products that are prevalent in pharmaceuticals, have not previously been compatible with systems for diarylmethyl ester coupling. Furthermore, the reaction can be performed stereospecifically to generate stereoinverted products. On the basis of DFT calculations, it is proposed that the oxidative addition of the diarylmethyl 2,3,4,5,6-pentafluorobenzoate substrate occurs via an SN2 pathway, which results in the inverted products. Mechanistic studies indicate that oxidative addition of the diarylmethyl 2,3,4,5,6-pentafluorobenzoate substrates to (IPr)Pd(0) results in the selective cleavage of the O-C(benzyl) bond in part because of a stabilizing η3-interaction between the benzyl ligand and Pd. This is in contrast to previously described Pd-catalyzed Suzuki-Miyaura reactions involving phenyl esters, which involve selective cleavage of the C(acyl)-O bond, because there is no stabilizing η3-interaction. It is anticipated that this fundamental knowledge will aid the development of new catalytic systems, which use esters as electrophiles in cross-coupling reactions.
- Dardir, Amira H.,Casademont-Reig, Irene,Balcells, David,Ellefsen, Jonathan D.,Espinosa, Matthew R.,Hazari, Nilay,Smith, Nicholas E.
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p. 2332 - 2344
(2021/06/28)
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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- The Trityl-Cation Mediated Phosphine Oxides Reduction
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Reduction of phosphine oxides into the corresponding phosphines using PhSiH3 as a reducing agent and Ph3C+[B(C6F5)4]? as an initiator is described. The process is highly efficient, reducing a broad range of secondary and tertiary alkyl and arylphosphines, bearing various functional groups in generally good yields. The reaction is believed to proceed through the generation of a silyl cation, which reaction with the phosphine oxide provides a phosphonium salt, further reduced by the silane to afford the desired phosphine along with siloxanes. (Figure presented.).
- Landais, Yannick,Laye, Claire,Lusseau, Jonathan,Robert, Frédéric
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supporting information
p. 3035 - 3043
(2021/05/10)
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- Strongly Entangled Triplet Acyl-Alkyl Radical Pairs in Crystals of Photostable Diphenylmethyl Adamantyl Ketones
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Radical pairs generated in crystalline solids by bond cleavage reactions of triplet ketones offer the unique opportunity to explore a frontier of spin dynamics where rigid radicals are highly entangled as the result of short inter-radical distances, large
- Garcia-Garibay, Miguel A.,Hipwell, Vince M.,Park, Jin H.,Rivera, Edris A.
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supporting information
p. 8886 - 8892
(2021/06/28)
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- Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
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The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
- Albrecht, Martin,Alshakova, Iryna D.
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p. 8999 - 9007
(2021/07/31)
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- Synthesis of Bis(trityl)iron(II) and Formation of the Iron(0)-Stabilized o, o-Isomer of Gomberg's Dimer
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Treatment of Fe(OAc)2 in THF with 2 equiv of Li(CPh3) at -25 °C results in the formation of [Fe(ν5-CPh3)2] (1) in 22% yield. Complex 1 was characterized by X-ray crystallography, NMR spectroscopy, and 57Fe M?ssbauer spectroscopy and features an ν5 binding
- Hayton, Trevor W.,Touchton, Alexander J.,Wu, Guang
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supporting information
p. 4045 - 4049
(2021/12/13)
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- Efficient heterogeneous palladium-catalyzed transfer hydrogenolysis of benzylic alcohols by formic acid
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An efficient heterogeneous palladium-catalyzed transfer hydrogenolysis- of primary, secondary, and tertiary benzylic alcohols using formic acid as hydrogen source has been developed. The resulting hydrocarbon products were obtained in excellent yields. Moreover, the system exhibits high chemoselectivity, reacting only with the hydroxy groups in the presence of other functional groups, and excellent re-cyclability.
- Afewerki, Samson,Córdova, Armando,Palo-Nieto, Carlos
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supporting information
p. 2330 - 2336
(2020/08/19)
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- Reductive Deamination with Hydrosilanes Catalyzed by B(C6F5)3
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The strong boron Lewis acid tris(pentafluorophenyl)borane B(C6F5)3 is known to catalyze the dehydrogenative coupling of certain amines and hydrosilanes at elevated temperatures. At higher temperature, the dehydrogenation pathway competes with cleavage of the C?N bond and defunctionalization is obtained. This can be turned into a useful methodology for the transition-metal-free reductive deamination of a broad range of amines as well as heterocumulenes such as an isocyanate and an isothiocyanate.
- Fang, Huaquan,Oestreich, Martin
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supporting information
p. 11394 - 11398
(2020/05/25)
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- Chemoselective Homologation-Deoxygenation Strategy Enabling the Direct Conversion of Carbonyls into (n+1)-Halomethyl-Alkanes
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The sequential installation of a carbenoid and a hydride into a carbonyl, furnishing halomethyl alkyl derivatives, is reported. Despite the employment of carbenoids as nucleophiles in reactions with carbon-centered electrophiles, sp3-type alkyl halides remain elusive materials for selective one-carbon homologations. Our tactic levers on using carbonyls as starting materials and enables uniformly high yields and chemocontrol. The tactic is flexible and is not limited to carbenoids. Also, diverse carbanion-like species can act as nucleophiles, thus making it of general applicability.
- Citarella, Andrea,Holzer, Wolfgang,Ielo, Laura,Langer, Thierry,Miele, Margherita,Pace, Vittorio,Urban, Ernst,Zehl, Martin
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supporting information
p. 7629 - 7634
(2020/10/12)
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- Direct Conversion of N-Alkylamines to N-Propargylamines through C-H Activation Promoted by Lewis Acid/Organocopper Catalysis: Application to Late-Stage Functionalization of Bioactive Molecules
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An efficient catalytic method to convert an α-C-H bond of N-alkylamines into an α-C-alkynyl bond was developed. In the past, such transformations were carried out under oxidative conditions, and the enantioselective variants were confined to tetrahydroisoquinoline derivatives. Here, we disclose a method for the union of N-alkylamines and trimethylsilyl alkynes, without the presence of an external oxidant and promoted through cooperative actions of two Lewis acids, B(C6F5)3 and a Cu-based complex. A variety of propargylamines can be synthesized in high diastereo-and enantioselectivity. The utility of the approach is demonstrated by the late-stage site-selective modification of bioactive amines. Kinetic investigations that shed light on various mechanistic nuances of the catalytic process are presented.
- Chan, Jessica Z.,Yesilcimen, Ahmet,Cao, Min,Zhang, Yuyang,Zhang, Bochao,Wasa, Masayuki
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supporting information
p. 16493 - 16505
(2020/10/26)
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- A Free-Radical Reduction and Cyclization of Alkyl Halides Mediated by FeCl2
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Iron mediated catalytic reactions are of great interest in the field of organic synthesis because they are economic and naturally abundant. However, the use of iron catalyst in the field of free radical cyclization or reduction of alkyl halides remains limited. Here we describe the use of an unprecedented combination of iron and zinc in the reduction and 5-exo-trig radical cyclization of alkyl halides under mild condition in the absence of added ligands or additives. The method is distinguished by its wide scope, functional group tolerance and the use of 1,4-cyclohexadiene as the source of hydrogen, which aids easy purification.
- Pulikottil, Feba Thomas,Pilli, Ramadevi,Murugesan, Vetrivelan,Krishnan, Chandu G.,Rasappan, Ramesh
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p. 2438 - 2442
(2019/04/30)
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- Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides
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For the first time, by using H3PO3/I2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H3PO3, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.
- Gao, Jing,Han, Li-Biao,Ma, Yonghao,Tang, Zilong,Wu, Xiaofang,Xiao, Jing
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p. 22343 - 22347
(2019/07/31)
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- Iron-catalyzed protodehalogenation of alkyl and aryl halides using hydrosilanes
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A simple and efficient iron-catalyzed protodehalogenation of alkyl and aryl halides using phenylhydrosilane is disclosed. The reaction utilizes FeCl3 without the requirement of ligands. Unactivated alkyl and aryl halides were successfully reduced in good yields; sterically hindered tertiary halides were also reduced including the less reactive chlorides. The scalability of this methodology was demonstrated by a gram-scale synthesis with a catalyst loading as low as 0.5 mol%. Notably, disproportionation of phenylsilane leads to diphenylsilane that further reduces the halides. Preliminary mechanistic studies revealed a non-radical pathway and the source of hydrogen is PhSiH3via deuterium labeling studies. Our methodology represents simplicity and provides a good alternative to typical tin, aluminum and boron hydride reagents.
- Pilli, Ramadevi,Balakrishnan, Venkadesh,Chandrasekaran, Revathi,Rasappan, Ramesh
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supporting information
p. 1749 - 1753
(2019/02/20)
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- Desulfurization method of organic compounds containing mercapto or disulfide bond
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The invention relates to a desulfurization method of organic compounds, in particular, organic compounds containing mercapto or a disulfide bond. The method comprises following steps: dissolving organic compounds containing mercapto or a disulfide bond by a solvent; adding a phosphine reagent and an initiator; and carrying out reactions in the presence of light to convert the substrate into corresponding desulfurization products. The organic compounds containing mercapto or a disulfide bond is R-SH or R-S-S-R; wherein R represents a primary carbon group, a secondary carbon group, a tertiary carbon group, an aryl group, or an acyl group. The reactions do not need any metal, and the reaction conditions are mild. Moreover, the desulfurization method has the advantages of high yield, wide substrate application range, and multiple suitable solvents, and is widely suitable for multiple kinds of mercapto-removing reactions and desulfurization reactions of disulfide.
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Paragraph 0026
(2019/10/01)
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- Method for constructing carbon-hydrogen bond by catalyzing alcohol dehydroxylation with palladium/platinum
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The invention discloses a method for constructing a carbon-hydrogen (deuterium) bond. The method comprises the following step: in the presence of a palladium/platinum catalyst and aryl halide, an alcohol hydroxyl group of an alcohol and hydrogen (deuterium) gas is replaced by hydrogen (deuterium) to construct the carbon-hydrogen (deuterium) bond. According to the method, the palladium/platinum catalyst is used as a catalyst, the green hydrogen (deuterium) gas is used as a hydrogen (deuterium) source, efficient alcohol dehydroxylation is performed at room temperature to construct the carbon-hydrogen (deuterium) bond, and the method is particularly suitable for constructing the carbon-deuterium bond and can be widely applied to synthesis of deuterated drugs.
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Paragraph 0104-0110; 0112
(2019/12/25)
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- Earth-Abundant Metal Catalysis Enabled by Counterion Activation
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A precatalyst activation strategy has been developed for earth-abundant metal catalysis enabled by counterion dissociation and demonstrated through alkene hydroboration. Commercially available iron and cobalt tetrafluoroborate salts were found to catalyze
- Agahi, Riaz,Challinor, Amy J.,Carter, Neil B.,Thomas, Stephen P.
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supporting information
p. 993 - 997
(2019/02/14)
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- Metal-Free Transfer Hydrobromination of C-C Triple Bonds
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A transfer hydrobromination of C-C triple bonds inititated by Br?nsted acids is reported. Hydrogen bromide is released stepwise from a bench-stable cyclohexa-1,4-diene-based surrogate, generating biphenyl and ethylene as waste. A range of vinyl bromides was prepared from terminal and internal, mainly acceptor-substituted alkynes with good functional-group tolerance.
- Chen, Weiqiang,Oestreich, Martin
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p. 4531 - 4534
(2019/06/27)
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- Rh(iii)-Catalysed solvent-free hydrodehalogenation of alkyl halides by tertiary silanes
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Efficient catalytic reduction of CDCl3 and other alkyl halides, including persistent organic pollutants, by different tertiary silanes using the unsaturated silyl-hydrido-Rh(iii) complex {Rh(H)[SiMe2(o-C6H4SMe)](PPh3)2}[BArF4] as a pre-catalyst is accomplished. The reactions are performed in a solvent-free manner. On account of experimental evidence, a simplified catalytic cycle is suggested for the hydrodehalogenation of CDCl3.
- Almenara,Azpeitia,Garralda,Huertos
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supporting information
p. 16225 - 16231
(2018/11/30)
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- Homogeneous Palladium-Catalyzed Transfer Hydrogenolysis of Benzylic Alcohols Using Formic Acid as Reductant
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We report the first homogeneous palladium-based transfer hydrogenolysis of benzylic alcohols using an in situ formed palladium-phosphine complex and formic acid as reducing agent. The reaction requires a catalyst loading as low as only 1 mol % of palladium and just a slight excess of reductant to obtain the deoxygenated alkylarenes in good to excellent yields. Besides demonstrating the broad applicability for primary, secondary and tertiary benzylic alcohols, a reaction intermediate could be identified. Additionally, it could be shown that partial oxidation of the applied phosphine ligand was beneficial for the course of the reaction, presumably by stabilizing the active catalyst. Reaction profiles and catalyst poisoning experiments were used to characterize the catalyst, the results of which indicate a homogeneous metal complex as the active species.
- Ciszek, Benjamin,Fleischer, Ivana
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supporting information
p. 12259 - 12263
(2018/08/28)
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- An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
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This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
- Sai, Masahiro
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supporting information
p. 4330 - 4335
(2018/10/15)
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- Unmodified Fe3O4 nanostructure promoted with external magnetic field: safe, magnetically recoverable, and efficient nanocatalyst for N- and C-alkylation reactions in green conditions
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Transition metal compounds have emerged as suitable catalysts for organic reactions. Magnetic compounds as soft Lewis acids can be used as catalysts for organic reactions. In this report, the Fe3O4 nanostructures were obtained from Fe2+ and Fe3+-salts, under an external magnetic field (EMF) without any protective agent. The X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy tools were used to characterize these magnetic compounds. The two-dimensional (2-D, it showed nanometric size in the two dimensions, nanorod structure) Fe3O4 compound showed high catalytic activity and stability in N- and C-alkylation reactions. A diverse range of N- and C-alkylation products were obtained in moderate to high yield under green and mild conditions in air. Also the N- and C-alkylation products can be obtained with different selectivity and yield by exposure reactions with EMF. Results of alkylation reactions showed that the presence of Fe(II) and Fe(III) species on the surface of magnetic catalysts (phase structure of magnetic compounds) are essential as very cheap active sites. Also, morphology of magnetic catalysts had influence on their catalytic performances. After the reaction, the catalyst/product(s) separation could be easily achieved with an external magnet and more than 95% of catalyst could be recovered. The catalyst was reused at least four times without any loss of its high catalytic activity for N- and C-alkylation reactions.
- Rafiee, Ezzat,Joshaghani, Mohammad,Abadi, Parvaneh Ghaderi-Shekhi
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p. 2503 - 2522
(2018/01/04)
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- Aromatization modulates the activity of small organic molecules as promoters for carbon-halogen bond activation
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The combination of small organic molecules and a base serves as a unique system for the activation carbon-halogen bonds in haloarenes by single electron transfer (SET). However, most of the molecules employed as promoters only allow for the activation of aryl iodides, and efficient activation of aryl bromides and chlorides under this mode is still rather challenging. Herein, we report the discovery of a structurally simple yet powerful promoter molecule, indoline, which exhibits unusually high activity in promoting the activation of haloarenes by SET. In the presence of t-BuOK and a trace amount of oxygen, indoline promotes the formation of aryl radicals not only from aryl iodides and bromides, but also from unactivated aryl chlorides (e.g., chlorobenzene) under relatively mild conditions. Mechanistic studies reveal the molecular basis for its high activity, for which the aromatization process plays a key role in modulating the electron transfer process.
- Yang, Huan,Chu, De-Zhao,Jiao, Lei
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p. 1534 - 1539
(2018/02/14)
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- Azaborines: Synthesis and use in the generation of stabilized boron-substituted carbocations
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A formal N-heterocyclic carbene insertion into the B-H bond of 9-BBN followed by a ring expansion reaction is reported. NHC-9-BBN adducts were reacted in one or two steps to give the corresponding di- or triazaborines. Hydride abstraction of selected species with [Ph3C]+ is facile, giving rise to 6π-aromatic cations with Lewis acidity comparable to Lewis acids commonly employed in frustrated Lewis pairs.
- Clarke,Eisenberger,Piotrkowski,Crudden
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supporting information
p. 1791 - 1795
(2018/02/17)
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- Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki Coupling of Trimethylammonium Salts and Arylboronic Acids
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An efficient palladium-catalyzed Suzuki coupling of 1,1-diarylmethyl-trimethylammonium triflates with arylboronic acids is reported. This reaction offers a novel approach to triarylmethane derivatives in good to excellent yields with the palladium-catalyzed C-N bond cleavage as the key feature. Broad substrate scope regarding both reaction partners are observed. Moreover, reactive functional groups such as vinyl and formyl groups are conserved in this transformation.
- Zhang, Zhenming,Wang, Hui,Qiu, Nianli,Kong, Yujing,Zeng, Wenjuan,Zhang, Yongquan,Zhao, Junfeng
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p. 8710 - 8715
(2018/07/21)
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- Carbenium ion formation by fragmentation of electrochemically generated oxonium ions
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Fragmentation of electrochemically generated oxonium ions can be exploited to form carbenium ions at a low oxidation potential in the presence of a nucleophile. The application of this concept is demonstrated for the allylation of carbenium ions generated by the anodic oxidation of stannylmethylethers.
- Lielpetere, Anna,Jirgensons, Aigars
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supporting information
p. 5094 - 5096
(2018/07/29)
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- Selective formation of heterocyclic: Trans -cycloalkenes by alkyne addition to a biphenylene-based phosphane/borane frustrated Lewis pair
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The intramolecular 1-PMes2/8-B(C6F5)2 substituted biphenylene frustrated Lewis pair 4 shows some behavior reminiscent of intermolecular FLP systems. It undergoes trans-1,2-addition to a series of 1-alkynes to give the respective heterocyclic eight-membered E-alkenes 8. The P/B FLP 4 also reacts with triplet dioxygen to yield the [P]-O-[B](OC6F5) containing oxygenation product.
- Li, Jun,Daniliuc, Constantin G.,Kehr, Gerald,Erker, Gerhard
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supporting information
p. 6344 - 6347
(2018/06/22)
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- Synthesis method of triphenylmethane
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The invention discloses a synthesis method of triphenylmethane. The synthesis method sequentially comprises the following steps: under the protection of inert gas, adding higher fatty acid or higher fatty acid salt and sodium into an organic solvent; drop
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Paragraph 0057-0064; 0072-0099
(2019/01/14)
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- Synthesis of tetraarylmethanes via a Friedel-Crafts cyclization/desulfurization strategy
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Tetraarylmethanes are an important class of molecules that contain four aryl groups bonded to a central carbon atom. The shape/three-dimensionality of these molecules makes them suitable for organic light-emitting diodes (OLEDs), organic solar cells, hydrogen storage, and even drug-delivery. Despite their importance, there are only a few methods available for their preparation. Herein, we report a simple procedure for the preparation of tetraarylmethanes that involves a bismuth-catalyzed Friedel-Crafts cyclization followed by a desulfurization reaction mediated by Raney nickel.
- Griffin, Paul J.,Fava, Matthew A.,Whittaker, St. John T.,Kolonko, Kristopher J.,Catino, Arthur J.
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p. 3999 - 4002
(2018/10/02)
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- Selective reaction of benzyl alcohols with HI gas: Iodination, reduction, and indane ring formations
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Reactions of benzyl alcohols with HI in solvent-free conditions were examined. Three types of reactions (iodination, reduction, and ring formation) occurred depending on the degree of crowding around the benzyl position and the benzylic stabilization of substrates. Results also showed that the ring formation to give indanes proceeded efficiently when HI was used, and that compounds with electron-rich aromatic rings gave indane derivatives in good yields.
- Matsumoto, Shoji,Naito, Masafumi,Oseki, Takehisa,Akazome, Motohiro,Otani, Yasuhiko
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p. 7254 - 7259
(2017/11/24)
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- Plant cell division inhibitor
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PROBLEM TO BE SOLVED: To provide a plant cell division inhibitor. SOLUTION: A plant cell division inhibitor comprises a triarylmethane derivative having a furan ring. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0083; 0084; 0085; 0088
(2017/12/07)
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- Copper-catalyzed cross-coupling reactions of non-activated primary, secondary or tertiary alkyl chlorides with phenylmagnesium bromide
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Efficient copper-catalyzed cross-coupling reactions of non-activated alkyl chlorides, including primary, secondary, and tertiary alkyl chlorides, with phenyl Grignard reagents were achieved. Preparation of phenylmagnesium bromide in 2-methyltetrahydrofuran is critical for the success of the reaction. This protocol expands the synthetic toolbox for the construction of C[sbnd]C bonds of non-activated primary, secondary, and tertiary alkyl chlorides via copper-catalyzed cross-coupling.
- Tao, Chuanzhou,Sun, Lei,Wang, Bin,Liu, Zhou,Zhai, Yadong,Zhang, Xiulian,Shi, Dahua,Liu, Weiwei
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supporting information
p. 305 - 308
(2017/01/03)
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- Synthesis of Di- and Triarylmethanes through Palladium-Catalyzed Reductive Coupling of N -Tosylhydrazones and Aryl Bromides
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A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)-C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.
- Xia, Yamu,Hu, Fangdong,Xia, Ying,Liu, Zhenxing,Ye, Fei,Zhang, Yan,Wang, Jianbo
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p. 1073 - 1086
(2017/02/24)
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- Efficient access to triarylmethanes through decarboxylation
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A new synthetic approach has been developed for efficient access to triarylmethanes by palladium catalyzed decarboxylative cross coupling reactions. The reaction features sp2-sp3 coupling where benzoic acids upon decarboxylation reac
- Saha, Tiash,Kumar, M. Srinivas Lavanya,Bera, Saurav,Karkara, Bidhu Bhusan,Panda, Gautam
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p. 6966 - 6971
(2017/02/05)
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- Synthesis of π-Extended Fluoranthenes via a KHMDS-Promoted Anionic-Radical Reaction Cascade
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An unprecedented KHMDS-promoted domino reaction to furnish hydroxyfluoranthenes is described. Biaryl compounds bearing acyl and naphthylalkenyl moieties are transformed into 9-hydroxydibenzo[j,l]fluoranthenes in a single step through the formation of an aromatic and a pentagonal ring system. A variety of fluoranthenes including those with extended π-conjugation, a heteroaromatic ring, and unsymmetrical substituents could be synthesized. Mechanistic studies reveal a unique reaction cascade where KHMDS acts as both a base and a single-electron donor.
- Ogawa, Naoki,Yamaoka, Yousuke,Yamada, Ken-Ichi,Takasu, Kiyosei
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supporting information
p. 3327 - 3330
(2017/06/23)
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- Perfluoroalkylated Main-Group Element Lewis Acids as Catalysts in Transfer Hydrogenation
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Transfer hydrogenation plays an important part in organic chemistry. Recently, strong Lewis acids like B(C6F5)3 have been introduced as a catalyst for these reactions. We successfully employed the Lewis acid (C2F5)3PF2 as a catalyst in the transfer hydrogenation between 1,3,5-trimethylcyclohexa-1,4-diene and 1,1-diphenylethylene. Surprisingly, the treatment of the diene alone with a catalytic amount of (C2F5)3PF2 led to a quantitative dismutation to mesitylene and 1,3,5-trimethylcyclohexane. With B(C6F5)3, there was a solvent-dependency: in CH2Cl2 mainly the dismutation products were obtained, while in toluene the evolution of H2 was observed. Additionally, the catalytic activity of various perfluoroalkylated germanes and silanes was tested.
- Bader, Julia,Maier, Alexander F. G.,Paradies, Jan,Hoge, Berthold
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p. 3053 - 3056
(2017/07/04)
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- FLP reactivity of [Ph3C]+ and (: O -tolyl)3P and the capture of a Staudinger reaction intermediate
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The frustrated Lewis pair (FLP) derived from the trityl cation and (o-tolyl)3P effects the activation of 1,4-cyclohexadiene and 1-bromo-4-ethynylbenzene and heterolytically cleaves the S-S bond of diphenyl disulfide. The FLP also captures pentafluorophenyl azide as the Staudinger reaction intermediate, a species that reacts with Ph3SiH to give the silyl analog.
- Zhou, Jiliang,Cao, Levy L.,Liu, Liu,Stephan, Douglas W.
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supporting information
p. 9334 - 9338
(2017/08/02)
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- Hydride Reduction by a Sodium Hydride-Iodide Composite
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Sodium hydride (NaH) is widely used as a Br?nsted base in chemical synthesis and reacts with various Br?nsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with unprecedented and unique hydride-donor chemical reactivity.
- Too, Pei Chui,Chan, Guo Hao,Tnay, Ya Lin,Hirao, Hajime,Chiba, Shunsuke
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supporting information
p. 3719 - 3723
(2016/03/26)
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- Oxo-rhenium catalyzed reductive coupling and deoxygenation of alcohols
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Representative benzylic, allylic and α-keto alcohols are deoxygenated to alkanes and/or reductively coupled to alkane dimers by reaction with PPh3 catalyzed by (PPh3)2ReIO2 (1). The newly discovered catalytic reductive coupling reaction is a rare C-C bond-forming transformation of alcohols.
- Kasner, Gabrielle R.,Boucher-Jacobs, Camille,Michael McClain,Nicholas, Kenneth M.
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supporting information
p. 7257 - 7260
(2016/06/09)
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- SO3H-functionalized organic-inorganic ionic liquids based on polyoxometalates characterization and their application in C-C coupling reaction
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Different ionic liquids (ILs) with SO3H as functional group were achieved by combining SO3H-functionalized organic cations and polyoxometalates (POM). The obtained salts were characterized and their catalytic activities investigated
- Rafiee, Ezzat,Mirnezami, Fakhrosadat,Kahrizi, Masoud
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p. 332 - 339
(2016/05/19)
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- Copper-mediated arylation with arylboronic acids: Facile and modular synthesis of triarylmethanes
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A facile and modular synthesis of triarylmethanes was achieved in good yield via a two-step sequence in which the final step is the copper(II)-catalyzed arylation of diarylmethanols with arylboronic acids. By using this protocol a variety of symmetrical and unsymmetrical triarylmethanes were synthesized. As an application of the newly developed methodology, we demonstrate a highyielding synthesis of the triarylmethane intermediate towards an anti-breast-cancer drug candidate.
- Rao, H. Surya Prakash,Rao, A. Veera Bhadra
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supporting information
p. 496 - 504
(2016/04/05)
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- Arylative Desulfonation of Diarylmethyl Phenyl Sulfone with Arenes Catalyzed by Scandium Triflate
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A scandium-triflate-catalyzed arylative desulfonation of diarylmethyl phenyl sulfones with arenes and heteroarenes was established. A variety of both sulfone and arene substrates were reacted to afford symmetric and nonsymmetric triarylmethanes in good yields. Further transformations of the resulting triarylmethanes and application to the concise synthesis of a bactericidal agent analogue were also demonstrated.
- Nambo, Masakazu,Ariki, Zachary T.,Canseco-Gonzalez, Daniel,Beattie, D. Dawson,Crudden, Cathleen M.
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supporting information
p. 2339 - 2342
(2016/06/09)
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- The Concise Synthesis of Unsymmetric Triarylacetonitriles via Pd-Catalyzed Sequential Arylation: A New Synthetic Approach to Tri- and Tetraarylmethanes
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The selective synthesis of multiarylated acetonitriles via sequential palladium-catalyzed arylations of chloroacetonitrile is reported. The three aryl groups are installed via a Pd-catalyzed Suzuki-Miyaura cross coupling reaction followed by back-to-back C-H arylations to afford triarylacetonitriles in three steps with no over-arylation at any step. The triarylacetonitrile products can be converted into highly functionalized species including tetraarylmethanes. This new strategy provides rapid access to a variety of unsymmetrical tri- and tetraarylmethane derivatives from simple, readily available starting materials. (Chemical Presented)
- Nambo, Masakazu,Yar, Muhammad,Smith, Joel D.,Crudden, Cathleen M.
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supporting information
p. 50 - 53
(2015/07/28)
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- Ethers as hydrogen sources in BF3·OEt2 promoted reduction of diphenylmethyl alcohols, ethers and esters to hydrocarbons
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A novel ether/BF3 reductive system has been described, in which diphenylmethanols and their ether and ester derivatives are used as starting materials. Reductions are performed in ether under reflux and an argon atmosphere, and the addition of extra water is beneficial to this reduction. A series of alkanes are able to be prepared with good to excellent yields. A deuterated experiment exhibits that the reductive hydrogen is generated from ether. The mechanism is discussed in detail to explain the observed reactivity.
- Li, Jiaqiang,Liu, Qing,Shen, Hang,Huang, Ruofeng,Zhang, Xiaohui,Xiong, Yan,Chen, Changguo
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p. 85291 - 85295
(2015/11/02)
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- Benzylation of arenes with benzyl halides synergistically promoted by in situ generated superacid boron trifluoride monohydrate and tetrahaloboric acid
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To examine the assembly methodology of diarylmethanes, a benzylation of (hetero)arenes with benzyl halides has been developed and various diarylmethanes were furnished with yields of up to 98% and regioselectivities of up to >99%. The complexation of the by-product halogen hydride with BF3·OEt2 generated the Bronsted acid BF3·HX (HBF3X, X=Cl or Br) in situ to synergistically promote the benzylation.
- Huang, Ruofeng,Zhang, Xiaohui,Pan, Jing,Li, Jiaqiang,Shen, Hang,Ling, Xuege,Xiong, Yan
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supporting information
p. 1540 - 1546
(2015/03/04)
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