共查询到20条相似文献,搜索用时 15 毫秒
1.
Prof. Dr. Miguel A. Esteruelas Antonio Martínez Dr. Montserrat Oliván Dr. Enrique Oñate 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(55):12632-12644
The saturated trihydride IrH3{κ3-P,O,P-[xant(PiPr2)2]} ( 1 ; xant(PiPr2)2=9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) activates the B−H bond of two molecules of pinacolborane (HBpin) to give H2, the hydride-boryl derivatives IrH2(Bpin){κ3-P,O,P-[xant(PiPr2)2]} ( 2 ) and IrH(Bpin)2{κ3-P,O,P-[xant(PiPr2)2]} ( 3 ) in a sequential manner. Complex 3 activates a C−H bond of two molecules of benzene to form PhBpin and regenerates 2 and 1 , also in a sequential manner. Thus, complexes 1 , 2 , and 3 define two cycles for the catalytic direct C−H borylation of arenes with HBpin, which have dihydride 2 as a common intermediate. C−H bond activation of the arenes is the rate-determining step of both cycles, as the C−H oxidative addition to 3 is faster than to 2 . The results from a kinetic study of the reactions of 1 and 2 with HBpin support a cooperative function of the hydride ligands in the B−H bond activation. The addition of the boron atom of the borane to a hydride facilitates the coordination of the B−H bond through the formation of κ1- and κ2-dihydrideborate intermediates. 相似文献
2.
Sukdev Bag Martin Petzold Aishanee Sur Suman Bhowmick Prof. Dr. Daniel B. Werz Prof. Dr. Debabrata Maiti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(40):9433-9437
Deuterium-labeled compounds find wide applications in kinetic studies, and within the pharmaceutical industry. An easily removable pyrimidine-based auxiliary has been employed for the meta-C−H deuteration of arenes. The scope of this Pd-catalyzed deuteration using commercially available [D1]- and [D4]-acetic acid has been demonstrated by its application in phenylacetic acid and phenylmethanesulfonate derivatives. A detailed mechanistic study led us to explore the reversibility of the non-rate determining C−H activation step. The present study of meta-deuterium incorporation illustrates the template morphology in terms of selectivity. The applicability of this method has been demonstrated by the selective deuterium incorporation into various pharmaceuticals. 相似文献
3.
Jorge Juan Cabrera-Trujillo Prof. Dr. Israel Fernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(51):11806-11813
The factors controlling the oxidative addition of C−C and C−H bonds in arenes mediated by AlI have been computationally explored by means of Density Functional Theory calculations. To this end, we compared the processes involving benzene, naphthalene and anthracene which are promoted by a recently prepared anionic AlI-carbenoid. It is found that this species exhibits a strong tendency to oxidatively activate C−H bonds over C−C bonds, with the notable exception of benzene, where the C−C bond activation is feasible but only under kinetic control reaction conditions. State-of-the-art computational methods based on the combination of the Activation Strain Model of reactivity and the Energy Decomposition Analysis have been used to rationalize the competition between both bond activation reactions as well as to quantitatively analyze in detail the ultimate factors controlling these transformations. 相似文献
4.
Reaction of LnCl3 first with three equivalent of C5H5Na in THF, then with one equivalent of N‐phenyldiethanolamine in THF‐DME afforded complexes of {[(C5H5)Ln((‐OCH2CH2)2N(C6H5)]4((4‐Cl)}[Na(DME)4] (Ln=Sm ( 1 ), Yb ( 2 )), being characterized by infrared spectra, elemental analyses and X‐ray crystallography. They are ionic pair compounds. The anionic part is a cluster, which can be viewed as a cyclic tetramer with four (C5H5)Ln units bridged by four pairs of OR groups, forming a pinwheel structure. Both the complexes can catalyze the ring‐opening polymerization of ε‐caprolactone under mild conditions, and complex 1 is more active than complex 2 . The polymerization accords with one order reaction kinetics for monomer concentration. The molecular weight increases with the yield increasing, and the molecular weight distribution is rather narrow (1.19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.
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
7.
Keigo E. Yamada Dr. Iain A. Stepek Dr. Wataru Matsuoka Prof. Dr. Hideto Ito Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2023,62(51):e202311770
Nanocarbons incorporating non-hexagonal aromatic rings - such as five-, seven-, and eight-membered rings - have various intriguing physical properties such as curved structures, unique one-dimensional packing, and promising magnetic, optical, and conductivity properties. Herein, we report an efficient synthetic approach to polycyclic aromatics containing seven-membered rings via a palladium-catalyzed intramolecular Ar−H/Ar−Br coupling. In addition to all-hydrocarbon scaffolds, heteroatom-embedded heptagon-containing polyarenes can be efficiently constructed with this method. Rhodium- and palladium-catalyzed sequential six- and seven-membered ring formations also afford complex heptagon-containing molecular nanocarbons from readily available arylacetylenes and biphenyl boronic acids. Detailed mechanistic analysis by DFT calculations showed the feasibility of seven-membered ring formation by a concerted metalation-deprotonation mechanism. This reaction can serve as a template for the synthesis of a wide range of seven-membered ring-containing molecular nanocarbons. 相似文献
8.
Joan J. Soldevila-Barreda Andrea Pettenuzzo Maria Azmanova Laia Rafols Amr A. A. Attia Alexandru Lupan Luca Ronconi Nicolas P. E. Barry Anaïs Pitto-Barry 《Helvetica chimica acta》2023,106(8):e202300064
The synthesis by transmetallation and in-depth characterisation by IR spectroscopy of five half-sandwich ruthenium and osmium dithiocarbamato isonipecotamide glycoconjugate complexes are presented herein. The evaluation of their in vitro cytotoxicity and of the zinc precursors’ in vitro cytotoxicity towards ovarian cancer (A2780 and A2780cisR) and normal prostate (PNT2) cells is reported. While the cytotoxicity of the compounds is rather limited, some selectivity is observed. 相似文献
9.
YUAN Wei-Guan TANG Wei ZHANG Hong-Ling ZHAO Bo XIONG Fang JING Lin-Hai QIN Da-Bin 《结构化学》2014,(3):12-19
Nickel(Ⅱ) complexes Ni(L1)2(1) and Ni(L2)2·CH3CN·H2O(2)(L1Cl = 2-(3-benzyl-2,3-dihydroimidazlo-1-yl)-N-(pyridin-2-yl)acetamide, chloride salt, L2Cl = 2-(3-naphthalene-2-ylmethyl)-2,3-dihydro-imidazlo-1-yl)-N-phenylacetamide, chloride salt) with amide-functionalized imidazolium NHC ligand were synthesized and determined by single-crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic system, space group P21/c with a = 9.2561(19), b = 15.138(3), c = 20.750(4) , β = 90.216(3)°, V = 2907.3(10) 3 and Z = 4. Complex 2 crystallizes in the orthorhombic system, space group Pbca with a = 15.5469(16), b = 15.3521(15), c = 31.177(3) , V = 7441.2(13) 3 and Z = 8. They are stable in the air and formed via intermolecular weak interactions, including C–H···π contacts and C–H···O hydrogen bonds. Complex 1 was applied in Suzuki coupling reaction through the investigation of reaction conditions under the optimal choice conditions: 80 ℃, K3PO4, 3% mol catalysts, 6% mol PPh3 and toluene as solvent system could afford 96% yield in 5 h. 相似文献
10.
Sulfonic acid group–functionalized nano- and microsilica with different sizes and shapes were synthesized. Silica nanospheres with an average size of 225 nm, silica microtubes, and fine silica gel were prepared and functionalized by sulfonic acid. Their catalytic activity was investigated in the three-component Biginelli reaction for the synthesis of dihydropyrimidinones. 相似文献
11.
Prof. Dr. Amir H. Hoveyda Yuebiao Zhou Dr. Ying Shi Prof. M. Kevin Brown Dr. Hao Wu Dr. Sebastian Torker 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21488-21543
A copper-based complex that contains a sulfonate N-heterocyclic carbene ligand was first reported 15 years ago. Since then, these organometallic entities have proven to be uniquely effective in catalyzing an assortment of enantioselective transformations, including allylic substitutions, conjugate additions, proto-boryl additions to alkenes, boryl and silyl substitutions, hydride-allyl additions to alkenyl boronates, and additions of boron-containing allyl moieties to N-H ketimines. In this review article, we detail the shortcomings in the state-of-the-art that fueled the development of this air stable ligand class, members of which can be prepared on multigram scale. For each reaction type, when relevant, the prior art at the time of the advance involving sulfonate NHC-Cu catalysts and/or subsequent key developments are briefly analyzed, and the relevance of the advance to efficient and enantioselective total or formal synthesis of biologically active molecules is underscored. Mechanistic analysis of the structural attributes of sulfonate NHC-Cu catalysts that are responsible for their ability to facilitate transformations with high efficiency as well as regio- and enantioselectivity are detailed. This review contains several formerly undisclosed methodological advances and mechanistic analyses, the latter of which constitute a revision of previously reported proposals. 相似文献
12.
Dr. Liselle Atkin Dr. Daniel L. Priebbenow 《Angewandte Chemie (International ed. in English)》2023,62(23):e202302175
Investigations into C−H amidation reactions catalysed by cationic half-sandwich d6 metal complexes revealed that the indenyl-derived catalyst [Ind*RhCl2]2 significantly accelerated the directed ortho C−H amidation of benzoyl silanes using 1,4,2-dioxazol-5-ones. Ring slippage involving a haptotropic η5 to η3 rearrangement of the indenyl complex proposedly enables ligand substitution at the metal centre to proceed via associative, rather than dissociative pathways, leading to significant rate and yield enhancements. Intriguingly, this phenomenon appears specific for C−H amidation reactions involving weakly coordinating carbonyl-based directing groups with no acceleration observed for the corresponding reactions involving strongly coordinating nitrogen-based directing groups. 相似文献
13.
Synthesis,Characterization, and Catalytic Activity of Heteroleptic Rhodium Complex for C–N Couplings
Zafar M. N. Perveen Fouzia Naz A. Mughal Ehsan Ullah Gul-e-Saba Hina K. 《Russian Journal of Coordination Chemistry》2019,45(1):62-73
Russian Journal of Coordination Chemistry - We have reported synthesis of complex [Rh(COD)(L{Me})Cl] (III), where L{Me} (II) is N-(1-methylpyridin-4(1H)-ylidene)benzamide and COD is... 相似文献
14.
Sabrina I. Kallne Thomas Braun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(35):9465-9469
An unprecedented reaction pathway for the borylation of SCF3‐containing arenes using [Rh(Bpin)(PEt3)3] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C H activations occur with a unique regioselectivity for the position ortho to the SCF3 group, which apparently serves as directing group. Borylated SCF3 compounds can serve as versatile building blocks. 相似文献
15.
Kodai Ishihara Yuna Araki Prof. Mizuki Tada Prof. Tsutomu Takayama Prof. Yoichi Sakai Prof. W. M. C. Sameera Prof. Yasuhiro Ohki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(43):9537-9546
Two transition-metal atoms bridged by hydrides may represent a useful structural motif for N2 activation by molecular complexes and the enzyme active site. In this study, dinuclear MoIV-FeII complexes with bridging hydrides, CpRMo(PMe3)(H)(μ-H)3FeCp* ( 2 a ; CpR=Cp*=C5Me5, 2 b ; CpR=C5Me4H), were synthesized via deprotonation of CpRMo(PMe3)H5 ( 1 a ; CpR=Cp*, 1 b ; CpR=C5Me4H) by Cp*FeN(SiMe3)2, and they were characterized by spectroscopy and crystallography. These Mo−Fe complexes reveal the shortest Mo−Fe distances ever reported (2.4005(3) Å for 2 a and 2.3952(3) Å for 2 b ), and the Mo−Fe interactions were analyzed by computational studies. Removal of the terminal Mo−H hydride in 2 a – 2 b by [Ph3C]+ in THF led to the formation of cationic THF adducts [CpRMo(PMe3)(THF)(μ-H)3FeCp*]+ ( 3 a ; CpR=Cp*, 3 b ; CpR=C5Me4H). Further reaction of 3 a with LiPPh2 gave rise to a phosphido-bridged complex Cp*Mo(PMe3)(μ-H)(μ-PPh2)FeCp* ( 4 ). A series of Mo−Fe complexes were subjected to catalytic silylation of N2 in the presence of Na and Me3SiCl, furnishing up to 129±20 equiv of N(SiMe3)3 per molecule of 2 b . Mechanism of the catalytic cycle was analyzed by DFT calculations. 相似文献
16.
Shu-Yong Song Dr. Xiaoyu Zhou Prof. Dr. Zhuofeng Ke Prof. Dr. Senmiao Xu 《Angewandte Chemie (International ed. in English)》2023,62(6):e202217130
Transition metal-catalyzed enantioselective C−H activation of prochiral sulfoximines for non-annulated products remains a formidable challenge. We herein report iridium-catalyzed enantioselective C−H borylation of N-silyl diaryl sulfoximines using a well-designed chiral bidentate boryl ligand with a bulky side arm. This method is capable of accommodating a broad range of substrates under mild reaction conditions, affording a vast array of chiral sulfoximines with high enantioselectivities. We also demonstrated the synthetic utility on a preparative-scale C−H borylation for diverse downstream transformations, including the synthesis of chiral version of bioactive molecules. Computational studies showed that the bulky side arm of the ligand confers high regio- and enantioselectivity through steric effect. 相似文献
17.
Solar Hydrocarbons: Single-Step,Atmospheric-Pressure Synthesis of C2−C4 Alkanes and Alkenes from CO2
Rui Song Zhao Li Jiuli Guo Paul N. Duchesne Chenyue Qiu Chengliang Mao Jia Jia Sanli Tang Yang-Fan Xu Wenzhe Zhou Lu Wang Wei Sun Xiaoliang Yan Liejin Guo Dengwei Jing Geoffrey A. Ozin 《Angewandte Chemie (International ed. in English)》2023,62(27):e202304470
Cobalt ferrite (CoFe2O4) spinel has been found to produce C2−C4 hydrocarbons in a single-step, ambient-pressure, photocatalytic hydrogenation of CO2 with a rate of 1.1 mmol g−1 h−1, selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe2O4 reconstructs to a CoFe−CoFe2O4 alloy-spinel nanocomposite which facilitates the light-assisted transformation of CO2 to CO and hydrogenation of the CO to C2−C4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery. 相似文献
18.
Xuejing Li Xingwang Deng Dr. Anthony G. Coyne Prof. Rajavel Srinivasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(34):8018-8023
Herein, we report the meta-nitration of arenes bearing ortho/para directing group(s) using the iridium-catalyzed C−H borylation reaction followed by a newly developed copper(II)-catalyzed transformation of the crude aryl pinacol boronate esters into the corresponding nitroarenes in a one-pot fashion. This protocol allows the synthesis of meta-nitrated arenes that are tedious to prepare or require multistep synthesis using the existing methods. The reaction tolerates a wide array of ortho/para-directing groups, such as −F, −Cl, −Br, −CH3, −Et, −iPr −OCH3, and −OCF3. It also provides regioselective access to the nitro derivatives of π-electron-deficient heterocycles, such as pyridine and quinoline derivatives. The application of this method is demonstrated in the late-stage modification of complex molecules and also in the gram-scale preparation of an intermediate en route to the FDA-approved drug Nilotinib. Finally, we have shown that the nitro product obtained by this strategy can also be directly converted to the aniline or hindered amine through Baran's amination protocol. 相似文献
19.
Dr. Jan Ulč Jaroslav Jacko Dr. Ivana Císařová Prof. Lubomír Pospíšil Dr. David Nečas Prof. Dr. Martin Kotora 《European journal of organic chemistry》2023,26(18):e202300153
Herein, we report the design and synthesis of a series of novel cationic nitrogen-embedded polyaromatic hydrocarbons with a planar geometry. The synthetic pathway is based on catalytic C−C/C−H bond activation relay that enabled preparation of regioselectively 5,6,10,11-tetrasubstituted naphtho[2,1,8-ija]quinolizinium salts bearing various types of substituents. Single-crystal X-ray analyses of selected compounds confirmed planarity of the quinolizinium core. Most of the prepared compounds exhibited strong fluorescence (Φs up to >99 %) ranging from 420–600 nm depending on the substitution pattern. According to DFT calculations LUMO is always distributed over the quinolizinium framework regardless of the attached substituents, whereas delocalization of HOMO is related to the substitution pattern. Electrochemical measurements show irreversible reduction of all compounds, which is supported by the calculated location of LUMO orbitals. 相似文献
20.
Dr. Yohei Ogiwara Yurika Iino Prof. Dr. Norio Sakai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(26):6513-6516
A method for the palladium/copper-catalyzed direct acylation of azoles with acyl fluorides is described. This study reports the first examples of acyl fluorides being used as acylation reagents in transition-metal-catalyzed aromatic C−H bond functionalization reactions. Depending on the reaction temperature, decarbonylative coupling may also occur. Mechanistic studies suggest that the cleavage of the aromatic C−H bond, promoted by a copper-phosphine species, is not the rate-limiting step of this acylation. 相似文献