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1.
Dr. Hong Lu Tian-Tian Zhao Jin-Hua Bai Dan Ye Prof. Dr. Peng-Fei Xu Prof. Dr. Hao Wei 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23743-23749
Highly selective divergent coupling reactions of benzocyclobutenones and indoles, in which the chemoselectivity is controlled by catalysts, are reported herein. The substrates undergo C2(indole)–C8(benzocyclobutenone) coupling to produce benzylated indoles and benzo[b]carbazoles in the Ni- and Ru-catalyzed reactions. A completely different selectivity pattern C2(indole)–C2(benzocyclobutenone) coupling to form arylated indoles is observed in the Rh-catalyzed reaction. Preliminary mechanistic studies suggest C−H and C−C activations in the reaction pathway. Synthetic utility of this protocol is demonstrated by the selective synthesis of three different types of carbazoles from the representative products. 相似文献
2.
《Chemical physics letters》1999,291(5-6):348-354
Electronic structures for mono- and dianionic species of two promising C36 fullerene isomers, 14 and 15, are investigated by means of the hybrid Hartree–Fock (HF)/density functional (DF) method. Structural deformations, charge distributions, and spin densities upon one- or two-electron reduction are explained in light of the lowest unoccupied molecular orbitals (LUMOs) of each neutral isomer. First electron affinities for the neutral isomers 14 and 15 are predicted to be 2.3 and 2.5 eV, respectively, facilitating n-type doping for C36 solids. The degrees of local aromaticity of the isomers 14 and 15 tend to decrease with reduction in contrast with C60. 相似文献
3.
Ionic fullerides of C 60 ? and C 60 2? with the silicon phthalocyanines cations were obtained in the reaction of PcSi(OH)2 with fullerene C60 in the presence of KOH in DMSO or in xylene and THF with the addition of 15C5 crown ether. The fullerides were characterized by electron absorption, 1H NMR and electron spin resonance spectra, and their reaction with O2 and CF3COOH were carried out. 相似文献
4.
Franziska Dahlmann Dennis F. Dinu Dr. Pavol Jusko Christine Lochmann Thomas Gstir Aravindh N. Marimuthu Prof. Dr. Klaus R. Liedl Prof. Dr. Sandra Brünken Prof. Dr. Roland Wester 《Chemphyschem》2023,24(15):e202300262
We present infrared predissociation spectra of C2N−(H2) and C 3N−(H2) in the 300–1850 cm−1 range. Measurements were performed using the FELion cryogenic ion trap end user station at the Free Electron Lasers for Infrared eXperiments (FELIX) laboratory. For C2N−(H2), we detected the CCN bending and CC−N stretching vibrations. For the C3N−(H2) system, we detected the CCN bending, the CC−CN stretching, and multiple overtones and/or combination bands. The assignment and interpretation of the presented experimental spectra is validated by calculations of anharmonic spectra within the vibrational configuration interaction (VCI) approach, based on potential energy surfaces calculated at explicitly correlated coupled cluster theory (CCSD(T)-F12/cc-pVTZ−F12). The H2 tag acts as an innocent spectator, not significantly affecting the C2,3N− bending and stretching mode positions. The recorded infrared predissociation spectra can thus be used as a proxy for the vibrational spectra of the bare anions. 相似文献
5.
Lu Luo Shuai Tang Jiangyue Wu Shiwei Jin Hua Zhang 《Chemical record (New York, N.Y.)》2023,23(4):e202300023
Aromatic organoboron compounds are highly valuable building blocks in organic chemistry. They were mainly synthesized through aromatic C−H and C−Het borylation, in which transition metal-catalysis dominate. In the past decade, with increasing attention to sustainable chemistry, numerous transition metal-free C−H and C−Het borylation transformations have been developed and emerged as efficient methods towards the synthesis of aromatic organoboron compounds. This account mainly focuses on recent advances in transition metal-free aromatic C−H, C−N, C−S, and C−O borylation transformations and provides insights to where further developments are required. 相似文献
6.
The past decades have witnessed the emergence of low-dimensional carbon-based nanostructures owing to their unique properties and various subsequent applications. It is of fundamental importance to explore ways to achieve atomically precise fabrication of these interesting structures. The newly developed on-surface synthesis approach provides an efficient strategy for this challenging issue, demonstrating the potential of atomically precise preparation of low-dimensional nanostructures. Up to now, the formation of various surface nanostructures, especially carbon-based ones, such as graphene nanoribbons (GNRs), kinds of organic (organometallic) chains and films, have been achieved via on-surface synthesis strategy, in which in-depth understanding of the reaction mechanism has also been explored. This review article will provide a general overview on the formation of one-dimensional carbon-based nanostructures via on-surface synthesis method. In this review, only a part of the on-surface chemical reactions (specifically, C−X (X=Cl, Br, I) and C−H activation reactions) under ultra-high vacuum conditions will be covered. 相似文献
7.
Dr. Krzysztof Kuciński Hendrik Simon Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(1):e202103837
The use of electricity over traditional stoichiometric oxidants is a promising strategy for sustainable molecular assembly. Herein, we describe the rhoda-electrocatalyzed C−H activation/alkylation of several N-heteroarenes. This catalytic approach has been successfully applied to several arenes, including biologically relevant purines, diazepam, and amino acids. The versatile C−H alkylation featured water as a co-solvent and user-friendly trifluoroborates as alkylating agents. Finally, the rhoda-electrocatalysis with unsaturated organotrifluoroborates proceeded by paired electrolysis. 相似文献
8.
Luo-Yan Liu Dr. Jennifer X. Qiao Dr. Kap-Sun Yeung Dr. William R. Ewing Prof. Dr. Jin-Quan Yu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):13935-13939
Fluorine is known to promote ortho-C−H metalation. Based upon this reactivity, we employed an activated norbornene that traps the ortho-palladation intermediate and is then relayed to the meta position, leading to meta-selective C−H arylation of fluoroarenes. Deuterium experiment suggests that this meta-arylation is initiated by ortho C−H activation and the catalytic cycle is terminated by C-2 protonation. A dual-ligand system is crucial for the observed high reactivity and site selectivity. Applying this approach to simple benzene or other arenes also affords arylation products with good yield and site selectivity. 相似文献
9.
In this study, we present a straightforward and environmentally friendly electrochemical approach for achieving selective halogenation of N-heteroarenes, including indoles, diazoles, pyrroles, quinolinone, and naphthols. Our method utilizes commercially available and affordable ammonium halides as halogen source. A library of valuable halogenated N-heteroarenes can be synthesized in moderate to excellent yields under mild conditions (transition-metal-free, oxidant-free, ethanol as solvent, atmospheric environment). The approach demonstrates a broad substrate scope, excellent tolerance towards various functional groups, and scalability. 相似文献
10.
Dr. Si-Hua Hou Adriana Y. Prichina Mengxi Zhang Prof. Dr. Guangbin Dong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7922-7930
To show the synthetic utility of the catalytic C−C activation of less strained substrates, described here are the collective and concise syntheses of the natural products (−)-microthecaline A, (−)-leubehanol, (+)-pseudopteroxazole, (+)-seco-pseudopteroxazole, pseudopterosin A–F and G—J aglycones, and (+)-heritonin. The key step in these syntheses involve a Rh-catalyzed C−C/C−H activation cascade of 3-arylcyclopentanones, which provides a rapid and enantioselective route to access the polysubstituted tetrahydronaphthalene cores presented in these natural products. Other important features include 1) the direct C−H amination of the tetralone substrate in the synthesis of (−)-microthecaline A, 2) the use of phosphoric acid to enhance efficiency and regioselectivity for problematic cyclopentanone substrates in the C−C activation reactions, and 3) the direct conversion of serrulatane into amphilectane diterpenes by an allylic cyclodehydrogenation coupling. 相似文献
11.
Chun Gu Dr. Weiqiang Yu Hanqing Zhao Prof. Dr. Song Shi Dr. Penghua Che Prof. Dr. Jie Xu Prof. Dr. Jin Gao 《ChemCatChem》2024,16(2):e202301169
A series of porous silica were prepared by alkyl-trimethyl-ammonium bromide with different carbon chain lengths (PS-n, n corresponds to the carbon chain length). These templates carried out precise structure regulation of porous silica. The Ru particles supported on porous silica behaved in precisely controlled size according to the pore diameter. When used in the hydrogenolysis of biomass polyols, a higher methane yield was achieved over Ru/PS-16. This result can be explained by the higher C2/C3 over Ru/PS-16 than others. 相似文献
12.
Jie Xu Weihua Qiu Xu Zhang Zhihan Wu Zhen Zhang Dr. Kai Yang Prof. Dr. Qiuling Song 《Angewandte Chemie (International ed. in English)》2023,62(47):e202313388
The direct C−H functionalization of 1,2-benzazaborines, especially asymmetric version, remains a great challenge. Here we report a palladium-catalyzed enantioselective C−H olefination and allylation reactions of 1,2-benzazaborines. This asymmetric approach is a kinetic resolution (KR), providing various C−B axially chiral 2-aryl-1,2-benzazaborines and 3-substituted 2-aryl-1,2-benzazaborines in generally high yields with excellent enantioselectivities (selectivity (S) factor up to 354). The synthetic potential of this reaction is showcased by late-stage modification of complex molecules, scale-up reaction, and applications. 相似文献
13.
Raolin Huang Prof. Dr. Frederic W. Patureau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(70):e202202135
A facile and environmentally friendly electrochemical protocol is herein reported for the C(sp2)−C(sp3) cross dehydrogenative coupling between imidazopyridines and N,N-dimethylanilines. The broad functional group compatibility includes halogens, ester, alcohol, sulfone as well as thiophene. This methodology is also suitable for benzo[d]imidazo[2,1-b]thiazole, thiazoimidazole and tetrahydroisoquinoline, and can be scaled up to 5 mmol. Mechanistic insights are discussed. 相似文献
14.
Sean R. Gitter Dr. Wei Pin Teh Dr. Xuejin Yang Alexander F. Dohoda Prof. Dr. Forrest E. Michael Prof. Dr. Andrew J. Boydston 《Angewandte Chemie (International ed. in English)》2023,62(23):e202303174
Post-polymerization modification (PPM) via direct C−H functionalization is a powerful synthetic strategy to convert polymer feed-stocks into value-added products. We found that a metal-free, Se-catalyzed allylic C−H amination provided an efficient method for PPM of polynorbornenes (PNBs) produced via ring-opening metathesis polymerization. Inherent to the mechanism of the allylic amination, PPM on PNBs preserved the alkene functional groups along the polymer backbone, while also avoiding transposition of the double bonds. Amination using a series of aryl sulfonamides led to good control over the degree of functionalization, access to a range of functionalities, and tunable thermal properties from the resulting polymers. 相似文献
15.
Yuhang Zhu Yilei Liao Shuqi Jin Liyuan Ding Prof. Dr. Guofu Zhong Prof. Dr. Jian Zhang 《Chemical record (New York, N.Y.)》2023,23(5):e202300012
Aryl alkenes represents one of the most widely occurring structural motif in countless drugs and natural products, and direct C−H functionalization of aryl alkenes provides atom- step efficient access toward valuable analogues. Among them, group-directed selective olefinic α- and β-C−H functionalization, bearing a directing group on the aromatic ring, has attracted remarkable attentions, including alkynylation, alkenylation, amino-carbonylation, cyanation, domino cyclization and so on. These transformations proceed by endo- and exo−C−H cyclometallation and provide aryl alkene derivatives in excellent site- stereo-selectivity. Enantio-selective α- and β- olefinic C−H functionalization were also covered to synthesis axially chiral styrenes. 相似文献
16.
Thomas Sephton Anastasios Charitou Dr. Cristina Trujillo Dr. Jonathan M. Large Dr. Sam Butterworth Prof. Michael F. Greaney 《Angewandte Chemie (International ed. in English)》2023,62(49):e202310583
Anilines are potentially high-value arylating agents, but are limited by the low reactivity of the strong C−N bond. We show that the reactive intermediate benzyne can be used to both activate anilines, and set-up an aryl transfer reaction in a single step. The reaction does not require any transition metal catalysts or stoichiometric organometallics, and establishes a metal-free route to valuable biaryl products by functionalizing the aniline C−N bond. 相似文献
17.
Single atom catalysts (SACs) have attracted much attention in recent years. As an essential group in SACs, M−X−C (X=nonmetallic element) materials have been demonstrated to be efficient in many reactions. However, identifying the active sites on M−X−C, especially under working conditions, is still challenging, which is crucial for chemists to further understand the mechanism underlying the reaction and better design proper SACs for specific reactions. Herein, the types and characterization of M−X−C are comprehensively summarized and discussed in this review. In addition to the basic information above, the challenges and opportunities remaining in this field will be also proposed to present a perspective to the research on the next step. 相似文献
18.
Dr. Friederike Ratsch Joss Pepe Strache Dr. Waldemar Schlundt Dr. Jörg-Martin Neudörfl Andreas Adler Sarwar Aziz Prof. Dr. Bernd Goldfuss Prof. Dr. Hans-Günther Schmalz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(14):4640-4652
The Ir-catalyzed conversion of prochiral tert-cyclobutanols to β-methyl-substituted ketones proceeds under comparably mild conditions in toluene (45–110 °C) and is particularly suited for the enantioselective desymmetrization of β-oxy-substituted substrates to give products with a quaternary chirality center with up to 95 % ee using DTBM-SegPhos as a chiral ligand. Deuteration experiments and kinetic isotope effect measurements revealed major mechanistic differences to related RhI-catalyzed transformations. Supported by DFT calculations we propose the initial formation of an IrIII hydride intermediate, which then undergoes a β-C elimination (C−C bond activation) prior to reductive C−H elimination. The computational model also allows the prediction of the stereochemical outcome. The Ir-catalyzed cyclobutanol cleavage is broadly applicable but fails for substrates bearing strongly coordinating groups. The method is of particular value for the stereo-controlled synthesis of substituted chromanes related to the tocopherols and other natural products. 相似文献
19.
M. Trinidad Martín Dr. Mario Marín Dr. Celia Maya Dr. Auxiliadora Prieto Prof. M. Carmen Nicasio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(48):12320-12326
Ni-catalyzed C−S cross-coupling reactions have received less attention compared with other C-heteroatom couplings. Most reported examples comprise the thioetherification of most reactive aryl iodides with aromatic thiols. The use of C−O electrophiles in this context is almost uncharted. Here, we describe that preformed Ni(II) precatalysts of the type NiCl(allyl)(PMe2Ar’) (Ar’=terphenyl group) efficiently couple a wide range of (hetero)aryl halides, including challenging aryl chlorides, with a variety of aromatic and aliphatic thiols. Aryl and alkenyl tosylates are also well tolerated, demonstrating, for the first time, to be competent electrophilic partners in Ni-catalyzed C−S bond formation. The chemoselective functionalization of the C−I bond in the presence of a C−Cl bond allows for designing site-selective tandem C−S/C−N couplings. The formation of the two C-heteroatom bonds takes place in a single operation and represents a rare example of dual electrophile/nucleophile chemoselective process. 相似文献
20.
《Chemical physics letters》1987,133(6):525-530
Large scale, vibrational CI calculations using a global ab initio potential energy surface are used to calculate multidimensional Franck-Condon overlaps from the ground vibrational state of HCO− and DCO− to all final bound and several quasibound vibrational states of HCO and DCO. The resulting Franck-Condon spectra are compared with recent experimental photoelectron spectra of HCO− and DCO−. 相似文献