- Chromium-Catalyzed Selective Cross-Electrophile Coupling between Unactivated C(aryl)-F and C(aryl)-O Bonds
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Chemically inert C(aryl)-F bonds have rarely been used to couple with other unactivated bonds, and this remains a challenge because of the difficulty of the successive cleavage of two unactivated bonds by metal catalysis. We report here the chromium-catalyzed cleavage of chemically inert C(aryl)-F bonds for coupling with unactivated C(aryl)-O bonds, allowing cross-electrophile coupling between unreactive aryl fluorides and aryl esters to be achieved in high regio- and chemoselectivity. The reactive Cr, which was formed in situ by reducing CrCl2, enables cleavage of the o-C(aryl)-F bonds to afford monovalent and quartet cyclochromate; subsequent bipyridyl-enabled insertion into the ester C(aryl)-O bond followed by reductive elimination allowed the orthogonal coupling of these two different and unactivated bonds. Mechanistic studies indicate that the bipyridyl ligand greatly enhances the reactivity of Cr in the cleavage of C(aryl)-O bonds, and the second oxidative addition may occur sluggishly compared with the reductive elimination in the catalytic cycle.
- Fan, Fei,Zhao, Lixing,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 561 - 568
(2022/03/15)
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- Palladium-Catalyzed Dehydrogenative Fluoroalkoxylation of Benzaldehydes
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A direct and efficient palladium-catalyzed oxidative dehydrogenative fluoroalkoxylation of benzaldehydes is reported here for the first time. The method features mild reaction conditions, good tolerance of functional groups, and a broad substrate scope. The protocol employs the transient directing group strategy, thereby avoiding the additional installation and removal of directing groups, endowing the method with great advantages of atom and step economy. The approach should find broad applications in drug synthesis and discovery processes.
- Jin, Long,Zhang, Xing-Long,Guo, Rui-Li,Wang, Meng-Yue,Gao, Ya-Ru,Wang, Yong-Qiang
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supporting information
p. 1921 - 1927
(2021/03/08)
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- Selective Cross-Dehydrogenative C(sp3)-H Arylation with Arenes
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Selective C(sp3)-C(sp2) bond construction is of central interest in chemical synthesis. Despite the success of classic cross-coupling reactions, the cross-dehydrogenative coupling between inert C(sp3)-H and C(sp2)-H bonds represents an attractive alternative toward new C(sp3)-C(sp2) bonds. Herein, we establish a selective inter-and intramolecular C(sp3)-H arylation of alcohols with nondirected arenes that thereby provides a general pathway to access a wide range of β-arylated alcohols, including tetrahydronaphthalen-2-ols and benzopyran-3-ols, with high to excellent chemo-and regioselectivity.
- Hao, Hong-Yan,Mao, Yang-Jie,Xu, Zhen-Yuan,Lou, Shao-Jie,Xu, Dan-Qian
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p. 2396 - 2402
(2020/03/13)
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- A Bu4N[Fe(CO)3(NO)]-Catalyzed Hemetsberger–Knittel Indole Synthesis
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The nucleophilic Fe complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the direct intramolecular amination of aryl vinyl azides to give the corresponding indole derivatives in good to excellent yields.
- Baykal, Aslihan,Plietker, Bernd
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supporting information
(2020/02/20)
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- Generation of Donor/Donor Copper Carbenes through Copper-Catalyzed Diyne Cyclization: Enantioselective and Divergent Synthesis of Chiral Polycyclic Pyrroles
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The generation of metal carbenes from readily available alkynes represents a significant advance in metal carbene chemistry. However, most of these transformations are based on the use of noble-metal catalysts and successful examples of such an asymmetric version are still very scarce. Here a copper-catalyzed enantioselective cascade cyclization of N-propargyl ynamides is reported, enabling the practical and atom-economical construction of diverse chiral polycyclic pyrroles in generally good to excellent yields with wide substrate scope and excellent enantioselectivities (up to 97:3 e.r.). Importantly, this protocol represents the first copper-catalyzed asymmetric diyne cyclization. Moreover, mechanistic studies revealed that the generation of donor/donor copper carbenes is presumably involved in this 1,5-diyne cyclization, which is distinctively different from the related gold catalysis, and thus it constitutes a novel way for the generation of donor/donor metal carbenes.
- Hong, Feng-Lin,Wang, Ze-Shu,Wei, Dong-Dong,Zhai, Tong-Yi,Deng, Guo-Cheng,Lu, Xin,Liu, Rai-Shung,Ye, Long-Wu
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supporting information
p. 16961 - 16970
(2019/10/16)
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- Rh-Catalyzed Annulation of ortho-C?H Bonds of 2-Arylimidazoles with 1,4,2-Dioxazol-5-ones toward 5-Arylimidazo[1,2-c]quinazolines
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A Rh-catalyzed unique and direct approach for constructing a series of 5-arylimidazo[1,2-c]quinazolines in moderate to excellent yields from simple and readily available 2-arylimidazoles and 3-phenyl-1,4,2-dioxazol-5-ones was described. This procedure pro
- Wu, Xiaopeng,Sun, Song,Xu, Shengbo,Cheng, Jiang
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supporting information
p. 1111 - 1115
(2018/01/27)
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- Weakly Coordinating, Ketone-Directed Cp?Co(III)-Catalyzed C-H Allylation on Arenes and Indoles
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Weakly coordinating, ketone-directed, regioselective monoallylation of arenes and indoles is reported using a stable and cost-effective high-valent cobalt(III)-catalyst to access several important molecular building blocks. The allylation proceeds smoothl
- Sk, Md Raja,Bera, Sourav Sekhar,Maji, Modhu Sudan
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p. 134 - 137
(2018/01/17)
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- Nitrate-promoted Selective C-H Fluorination of Benzamides and Benzeneacetamides
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A versatile and site-selective nitrate-promoted C-H bond fluorination using various weak coordinating amides as intrinsic directing groups was developed. Diverse tertiary and secondary amides underwent selective aromatic C-H bond fluorination, which featu
- Ning, Xing-Qian,Lou, Shao-Jie,Mao, Yang-Jie,Xu, Zhen-Yuan,Xu, Dan-Qian
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p. 2445 - 2448
(2018/04/27)
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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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p. 420 - 430
(2017/04/26)
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- Rh(III)-Catalyzed bilateral cyclization of aldehydes with nitrosos toward unsymmetrical acridines proceeding with C-H functionalization enabled by a transient directing group
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A Rh(iii)-catalyzed bilateral cyclization was developed for the efficient construction of acridines proceeding with C-H functionalization whereby in situ formation and removal of an imino transient directing group in the presence of catalytic amount of BnNH2 are achieved. In this transformation, a sequential Rh(iii)-catalyzed C-H amination, cyclization, and aromatization process was involved.
- Hu, Weiming,Zheng, Qingheng,Sun, Song,Cheng, Jiang
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supporting information
p. 6263 - 6266
(2017/07/07)
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- Hypervalent iodine(III)-mediated benzannulation of enamines with alkynes: An efficient synthesis of substituted aminonaphthoic acid derivatives
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An intermolecular two C-C bond formation procedure for the synthesis of carbocycles mediated by hypervalent iodine(III) reagents was developed. This metal free protocol provided a new approach for the synthesis of useful substituted 1-amino-2-naphthoic ac
- Gao, Peng,Fan, Mingjin,Bai, Zijing,Wei, Yunyang
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p. 479 - 485
(2015/04/22)
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- Zinc-Catalyzed Alkyne Oxidation/C-H Functionalization: Highly Site-Selective Synthesis of Versatile Isoquinolones and β-Carbolines
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An efficient zinc(II)-catalyzed alkyne oxidation/C£H functionalization sequence was developed, thus leading to highly site-selective synthesis of a variety of isoquinolones and β-carbolines. Importantly, in contrast to the well-established gold-catalyzed intermolecular alkyne oxidation, over-oxidation can be completely suppressed in this system and the reaction most likely proceeds by a Friedel-Crafts-type pathway. Mechanistic studies and theoretical calculations are described.
- Li, Long,Zhou, Bo,Wang, Yong-Heng,Shu, Chao,Pan, Yi-Fei,Lu, Xin,Ye, Long-Wu
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supporting information
p. 8245 - 8249
(2015/07/07)
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- PROCESS FOR THE ACTIVATION OF THE C-H BOND OF ORGANIC COMPOUNDS AND A REACTIONS SYSTEM SERVING THE PROCESS
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A process is disclosed for the activation of the single covalent carbon-hydrogen bond of organic substrate compounds, and for the reaction, in particular deuteratrion thereof within mild reaction conditions, wherein said organic substrate compound is contacted with a Rutenium-complex, a phosphine, and a source of a hydrogen-substituent, thus the hydrogen of the C-H-bond is substituted by a hydrogen-substituent through the activation of the C-H bond by an in situ prepared Ru-phosphine catalyst. A reaction system for reacting of the C-H-bond is also disclosed. The process makes possible the selective reaction of the C-H-bond.
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Page/Page column 8
(2014/01/18)
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- Palladium-catalyzed intramolecular amidation of C(sp2)-H bonds: Synthesis of 4-aryl-2-quinolinones
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Figure presented A catalytic synthetic approach for the synthesis of 2-quinolinone compounds through a Pd-catalyzed C(sp2)-H functionalization/intramolecular amidation sequence is described. The cyclization process efficiently proceeds in the p
- Inamoto, Kiyofumi,Saito, Tadataka,Hiroya, Kou,Doi, Takayuki
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supporting information; experimental part
p. 3900 - 3903
(2010/07/05)
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- Examination of the mechanism of Rh2(II)-catalyzed carbazole formation using intramolecular competition experiments
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(Chemical Equation Presented) The use of a rhodium(II) carboxylate catalyst enables the mild and stereoselective formation of carbazoles from biaryl azides. Intramolecular competition experiments of triaryl azides suggested the source of the selectivity. A primary intramolecular kinetic isotope effect was not observed, and correlation of the product ratios with Hammett σ+ values produced a plot with two intersecting lines with opposite ρ values. These data suggest that electronic donation by the biaryl π-system accelerates the formation of rhodium nitrenoid and that C-N bond formation occurs through a 4π-electron-5-atom electrocyclization.
- Stokes, Benjamin J.,Richert, Kathleen J.,Driver, Tom G.
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supporting information; experimental part
p. 6442 - 6451
(2009/12/24)
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- Mechanistical studies on C-H activation reactions of benzaldimines using selectively deuterated ligands: Synthesis and crystal structures of [μ2-η3-(R)N-CH 2-C=C-C(H)=C(H)-C(H)=C(H)]Fe2(CO)6
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The reaction of Fe2(CO)9 with imine ligands derived from benzaldehyde leads to the formation of dinuclear iron cluster compounds of the general formula [μ2-η3-N-CH 2-C=C-C(H)=C(H)-C(H)=C(H)]Fe2(CO)6 by a C-H activation/1,3-hydrogen shift reaction sequence. Six cluster compounds with alkyl and aryl substituents bound to nitrogen have been synthesised and characterised, five of them also by means of X-ray crystallography. The mechanism of the reaction has been investigated by the use of ligands being selectively deuterated in the 2-position. By several NMR experiments including deuterium spectra it can be demonstrated that the hydrogen/deuterium atom of the activated aromatic C-H bond is transferred to the former imine carbon atom producing a methylene group instead and that this reaction strictly follows an intramolecular pathway.
- Imhof, Wolfgang,Goebel, Angela,Ohlmann, Dietmar,Flemming, Joachim,Fritzsche, Hartmut
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- Structural dependence of isotope effects in 1H and 13C nuclear magnetic resonance spectra of the trans-N-benzylideneaniline imino group
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Deutrium- and 15N-induced isotope effects on 1H and 13C chemical shifts of the imino moiety of 16 trans-N-benzylideneaniline (tBA) isotopomers were determined and analysed. These effects appear to be a sensitive probe of m
- Novak, Predrag,Meic, Zlatko,Vikic-Topic, Drazen,Smrecki, Vilko,Plavec, Janez
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p. 327 - 333
(2007/10/03)
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- 1,2,4,6-CYCLOHEPTATETRAENE: THE KEY INTERMEDIATE IN ARYLCARBENE INTERCONVERSIONS AND RELATED C7H6 REARRANGEMENTS
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Thermolysis or photolysis of phenyldiazomethane (2) produces phenylmethylene (3), which ring-expands to give 1,2,4,6-cycloheptatetraene (6).Spectroscopic and chemical evidence rule out bicyclo(4.1.0)hepta-2,4,6-triene (4), cycloheptatrienylidene (5), and bicyclo(3.2.0)hepta-1,3,6-triene (11) intermediates.The strained allene in cycloheptatetraene (6) exhibits infrared absorption at 1824 and 1816 cm-1.Deuterium substitution produces the expected 10-cm-1 shift in the allene absorption.Fluorine or chlorine substitution substantially enhances the allene absorption intensity.Deuterium labeling studies reveal that the intramolecular chemistry of cycloheptatetraene (6) involves reversible thermal or photochemical equilibriation with phenylmethylene (3).The intermolecular chemistry of 6 involves dimerization.At temperatures as low as 10 K, 6 forms a labile (2+2) dimer,7, which undergoes thermally allowed, electrocyclic ring opening to give heptafulvalene (8) upon warming to room temperature.The rearrangements of 7-acetoxynorbornadiene (9), 2-diazobicyclo(3.2.0)hepta-3,6-diene (31), and 8-diazobicyclo(2.2.2)octa-2,5-dien-7-one (33) all involve cycloheptatetraene (6) intermediates.
- McMahon, Robert J.,Abelt, Christopher J.,Chapman, Orville L.,Johnson, Jeffery W.,Kreil, Curits L.,et al.
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p. 2456 - 2469
(2007/10/02)
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- Unusual Deuterium Isotope Effects in 13C NMR Spectra of trans-Stilbene
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A detailed analysis of the 13C NMR spectra of trans-stilbene and ten deuteriated trans-stilbenes has been undertaken.Some unusual deuterium isotope effects on carbon-hydrogen spin-spin coupling constants could not be explained by the ordinary primary and
- Meic, Zlatko,Vikic-Topic, Drazen,Gusten, Hans
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p. 237 - 244
(2007/10/02)
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- PREPARATION D'ESTERS PAR DESHYDROGENATION D'ALCOOLS PRIMAIRES EN PHASE LIQUIDE CATALYSEE PAR L'OXYDE DE CUIVRE - OBSERVATIONS PRELIMINAIRES
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Linear primary alcohols with at least 7 carbon atoms are quite quantitatively transformed in esters, by CuO, at temperatures > 17O deg C, without air in liquid phase. Preponderant influence of carbon in position 2 is evidenced.In the same conditions lactones are obtained from diols, and benzylic alcohols undergoes, by hydride transfer, a disproportionation into toluene, benzaldehyde and water.
- Berthon, Bruno,Forestiere, Alain,Leleu, Gerard,Sillion, Bernard
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p. 4073 - 4076
(2007/10/02)
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