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1.
Dr. Wangyang Ma Iskander Douair Prof. Dr. Laurent Maron Prof. Dr. Qing Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(60):13573-13577
The reaction of uranacyclopropene complex (C5Me5)2U[η2-1,2-C2(SiMe3)2] with B-aryl bis(alkynyl)borane PhB(C≡CPh)2 led to the first six-membered uranium metallaboracycle, while the reaction with B-amino bis(alkynyl)borane (Me3Si)2NB(C≡CPh)2 afforded an unexpected uranaborabicyclo[2.2.0] complex via [2+2] cycloaddition. The reaction with CuCl revealed the non-innocent property of the rearranged bis(alkynyl)boron species towards oxidant. The reactions with isocyanide DippNC: (Dipp=2,6-iPr2-C6H3) and isocyanate tBuNCO afforded the novel uranaborabicyclo[3.2.0] complexes. All new complexes have been structurally characterized. DFT calculations were performed to provide more insights into the electronic structures and the reaction mechanism. 相似文献
2.
S. S. Rynin V. I. Faustov S. E. Boganov M. P. Egorov O. M. Nefedov 《Russian Chemical Bulletin》2010,59(6):1099-1109
The cycloaddition reactions of dichlorogermylene GeCl2 to ethylene, buta-1,3-diene, and hexa-1,3,5-triene were studied within the framework of the density functional theory (PBE
and B3LYP density functionals) and by the ab initio CBS-QB3 method. The energy characteristics of the reaction of GeCl2 with ethylene were refined and non-empirical quantum chemical calculations of reaction pathways in the GeCl2 + buta-1,3-diene and GeCl2 + hexa-1,3,5-triene systems were carried out for the first time. It was shown that the [2+1] cycloaddition reactions are
kinetically hindered and thermodynamically unfavorable, while the [4+1] and [6+1] cycloaddition reactions are characterized
by low barriers and result in thermodynamically favorable products. For the [4+1] cycloaddition to buta-1,3-diene and [6+1]
cycloaddition to hexa-1,3,5-triene, the most energetically favorable reaction pathways involve a suprafacial and antarafacial
approach of reactants, respectively. 相似文献
3.
《Journal of computational chemistry》2017,38(28):2388-2395
N‐alkenyl maleimides are found to exhibit spin state‐specific chemoselectivities for [2 + 2] and [5 + 2] photocycloadditions; but, reaction mechanism is still unclear. In this work, we have used high‐level electronic structure methods (DFT, CASSCF, and CASPT2) to explore [2 + 2] and [5 + 2] photocycloaddition reaction paths of an N‐alkenyl maleimide in the S1 and T1 states as well as relevant photophysical processes. It is found that in the S1 state [5 + 2] photocycloaddition reaction is barrierless and thus overwhelmingly dominant; [2 + 2] photocycloaddition reaction is unimportant because of its large barrier. On the contrary, in the T1 state [2 + 2] photocycloaddition reaction is much more favorable than [5 + 2] photocyclo‐addition reaction. Mechanistically, both S1 [5 + 2] and T1 [2 + 2] photocycloaddition reactions occur in a stepwise, nonadiabatic means. In the S1 [5 + 2] reaction, the secondary C atom of the ethenyl moiety first attacks the N atom of the maleimide moiety forming an S1 intermediate, which then decays to the S0 state as a result of an S1 → S0 internal conversion. In the T1 [2 + 2] reaction, the terminal C atom of the ethenyl moiety first attacks the C atom of the maleimide moiety, followed by a T1 → S0 intersystem crossing process to the S0 state. In the S0 state, the second C C bond is formed. Our present computational results not only rationalize available experiments but also provide new mechanistic insights. © 2017 Wiley Periodicals, Inc. 相似文献
4.
Rajkumar Samala Ranadheer Kumar M Ashok Kumar Bapuram Venkatarathnam Nasipireddy Sirassu Narsimha 《Journal of heterocyclic chemistry》2024,61(4):600-610
In this study, we designed and synthesized several novel fused [1,2,3]triazolo [4′,5′:3,4]pyrrolo[1,2-a]thieno[2,3-d]pyrimidine derivatives using in a single [3 + 2] reaction cycloaddition reaction of 3-(3-iodoprop-2-yn-1-yl)thieno[2,3-d]pyrimidin-4(3H)-one ( 4 ) followed by C-C bond coupling with various aryl azides in a PEG-400 medium. All of the newly synthesized compounds were evaluated in vitro for EGFR kinase inhibitory action as well as anti-breast cancer activity against MDA-MB-231 and MCF-7 breast cancer cell lines. When compared to the reference molecule, erlotinib, the majority of the compounds demonstrated adequate efficacy. The most promising compounds, 5g and 5i , demonstrated excellent anticancer activity against both cancer cell lines, with IC50 values ranging from 04.17 ± 0.55 to 8.65 ± 0.89 μM, respectively, as well as excellent kinase inhibitory activities (EGFR: IC50 = 0.467 ± 0.063 and 0.412 ± 0.081 μM). The in silico studies of five potent compounds 5f , 5g , 5h , 5i , and 5k were also carried out to identify the interactions against the EGFR receptor and found that the energy calculations were covenant with the obtained IC50 values. 相似文献
5.
Robin Schoemaker Philipp Kossatz Dr. Kai Schwedtmann Dr. Felix Hennersdorf Prof. Dr. Jan J. Weigand 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(51):11734-11741
Synthesis of mixed-substituted tetraphosphetanes (RP−PtBu)2 (R=Ph ( 4 ), Py ( 5 ); Py=2-pyridyl) is achieved from the condensation of dipyrazolylphosphanes RPpyr2 (R=Py ( 1 ), Ph ( 3 ); pyr=3,5-dimethylpyrazolyl) as P1-building block (R−P) and tBuPH2 in an equimolar ratio. Compound 5 is of special interest since the presence of two pyridyl-substituents as well as the P4-core allows for a rich coordination chemistry with coinage metal salts [Cu(MeCN)4][OTf], Ag[OTf] and in situ formed [Au(tht)][OTf] (tht=tetrahydrothiophene). Both tetraphosphetanes undergo alkylation reaction with MeOTf to give a series of tetraphosphetanium and tetraphosphetanediium triflate salts with additional methylation of the pyridyl-moiety in case of 5 resulting in interesting novel cyclic trications. Harsh reaction condition and an excess of MeOTf converts 5 into the cyclic trication [-P(MePy)PMe2P(MePy)PtBu-]3+ ( 13 3+; MePy=1-methylpyridiniumyl) through the elimination of isobutene. This salt undergoes a complicated rearrangement reaction involving a P−P/P−P bond metathesis to form trication [-P(MePy)3PtBu-]3+ ( 17 3+) when reacted with Me2PPMe2. 相似文献
6.
Jing Tang Dong-Hui Xu Xin Wang Laicai Li Xiang-Yang Liu Xin-Tong Su Jianmin Guo Bin Zhai 《International journal of quantum chemistry》2020,120(14):e26236
Here we employ density functional theory calculations to systematically investigate the underlying mechanism of Cu(OTf)2-catalyzed [3+2] cycloaddition reactions in the synthesis of CF3-substituted pyrazolidines. About eight possible initial configurations of the [3+2] reaction is considered, and all relevant reactants, transition states, and products are optimized. Based on these structures, internal reaction coordinate paths, and wavefunction analysis results, we conclude that the Cu(OTf)2-catalyzed [3+2] cycloaddition follows a concerted asynchronous mechanism. The C N bond forms immediately after the formation of the C C bond. Among the eight reaction paths, the energy barrier for the [3+2] reaction that leads to the CF3-substituted syn-pyrazolidine is the lowest, ∼5.4 kcal/mol, which might result in the diastereoselectivity that is observed in the experiment. This work not only gives the detailed mechanism of the Cu(OTf)2-catalyzed [3+2] cycloaddition but can also be helpful for the future designation of Cu(OTf)2-based cycloaddition processes. 相似文献
7.
8.
Stereoselective Rhodium‐Catalysed [2+2+2] Cycloaddition of Linear Allene–Ene/Yne–Allene Substrates: Reactivity and Theoretical Mechanistic Studies
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Ewelina Haraburda Òscar Torres Dr. Teodor Parella Prof. Dr. Miquel Solà Dr. Anna Pla‐Quintana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):5034-5045
Allene–ene–allene ( 2 and 5 ) and allene–yne–allene ( 3 and 7 ) N‐tosyl and O‐linked substrates were satisfactorily synthesised. The [2+2+2] cycloaddition reaction catalysed by the Wilkinson catalyst [RhCl(PPh3)3] was evaluated. Substrates 2 and 5 , which bear a double bond in the central position, gave a tricyclic structure in a reaction in which four contiguous stereogenic centres were formed as a single diastereomer. The reaction of substrates 3 and 7 , which bear a triple bond in the central position, gave a tricyclic structure with a cyclohexenic ring core, again in a diastereoselective manner. All cycloadducts were formed by a regioselective reaction of the inner allene double bond and, therefore, feature an exocyclic diene motif. A Diels–Alder reaction on N‐tosyl linked cycloadducts 8 and 10 allowed pentacyclic scaffolds to be diastereoselectively constructed. The reactivity of the allenes on [2+2+2] cycloaddition reactions was studied for the first time by density functional theory calculations. This mechanistic study rationalizes the order in which the unsaturations take part in the catalytic cycle, the reactivity of the two double bonds of the allene towards the [2+2+2] cycloaddition reaction, and the diastereoselectivity of the reaction. 相似文献
9.
E. W. Kaiser 《国际化学动力学杂志》1993,25(8):667-680
Relative rate experiments using UV photolysis of F2 or Cl2 have been used to determine rate constant ratios for several hydrofluorocarbon (HFC) reactions with Cl or F atoms and for HFC alkyl radicals with molecular halogens. For mixtures with F2 present, dark reactions are, also, observed which are attributed to thermal dissociation of the F2 to form F atoms. At 296 K, the rate of reaction (1a) [CF2HCH3 + F → CF2CH3 + HF] relative to (1b) [CF2HCH3 + F → CF2HCH2 + HF] is k1a/k1b = 0.73 (±0.13) and is independent of T (= 262–348 K). At 296 K, the ratio of reaction (2a) [CF2HCH2F + F → products] to that of (k1a + k1b) is (k1a + k1b)/k2a = 2.7 (±0.4), and for reaction (2b) [CF3CH3 + F → products] (k1a + k1b)/k2b = 22 ± 12. The temperature dependence (263–365 K) of the rate constant of reaction (3) [CF3CFH2 + Cl → products] relative to reaction (4) [CF3CFClH + Cl → products] is k3/k4(±10%) = 1.55 exp(?300 K/T). For the alkyl radicals formed from HFC 152a (CF2HCH2 and CF2CH3) and from HFC 134a (CF3CFH), rate constants for the reactions with F2 and Cl2 were measured relative to their reactions with O2. The rate constant of reaction (5cl) [CF2CH3 + Cl2 → CF2ClCH3 + Cl] relative to (5o) [CF2CH3 + O2 → CF2(O2)CH3] is k5cl/k5o(±15%) = 0.3 exp(200 K/T). For reaction (5f) [CF2CH3 + F2 → CF3CH3 + F], k5f/k5o(±35%) = 0.23. The ratio for reaction (6f) [CF2HCH2 + F2 → CF2HCH2F + F] relative to (6o) [CF2HCH2 + O2 → CF2HCH2O2] is k6f/k6o(±40%) = 1.23 exp(?730 K/T). The rate constant ratio for reaction (8cl) [CF3CFH + Cl2 → CF3CFClH + Cl] relative to reaction (8o) [CF3CFH + O2 → CF3CFHO2] is k8cl/k8o(±18%) = 0.16 exp(?940 K/T). For reaction (8f) [CF3CFH + F2 → CF3CF2H + F], k8f/k8o(±35%) = 0.6 exp(?860 K/T). © 1993 John Wiley & Sons, Inc. 相似文献
10.
《应用有机金属化学》2017,31(11)
Superparamagnetic nanoparticles of modified thioglycolic acid (γ‐Fe2O3@SiO2‐SCH2CO2H) represent a new, efficient and green catalyst for the one‐pot synthesis of novel spiro[benzo[a ]benzo[6,7]chromeno[2,3‐c ]phenazine] derivatives via domino Knoevenagel–Michael–cyclization reaction of 2‐hydroxynaphthalene‐1,4‐dione, benzene‐1,2‐diamines, ninhydrin and isatin. This novel magnetic organocatalyst was easily isolated from the reaction mixture by magnetic decantation using an external magnet and reused at least six times without significant loss in its activity. The catalyst was fully characterized using various techniques. This procedure was also applied successfully for the synthesis of benzo[a ]benzo[6,7]chromeno[2,3‐c ]phenazines. 相似文献
11.
Liqiang Wu Yanfang Wu Fulin Yan Lizhen Fang 《Monatshefte für Chemie / Chemical Monthly》2010,14(4):871-875
Abstract
Three-component one-pot synthesis of some novel 12-aryl-12H-benzo[i][1,3]dioxolo[4,5-b]xanthene-6,11-diones involving treatment of 3,4-methylenedioxyphenol, aldehydes, and 2-hydroxy-1,4-naphthoquinone in presence of HClO4–SiO2 was achieved, and this reaction was extended to preparation of 10-aryl-6,7,8,10-tetrahydro-7,7-dimethyl-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones by three-component reaction of 3,4-methylenedioxyphenol, aldehydes, and dimedone. 相似文献12.
Diversity in Gold‐Catalyzed Formal Cycloadditions of Ynamides with Azidoalkenes or 2H‐Azirines: [3+2] versus [4+3] Cycloadditions
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Samir Kundlik Pawar Rajkumar Lalji Sahani Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(30):10843-10850
Gold‐catalyzed cycloadditions of ynamides with azidoalkenes or 2H‐azirines give [3+2] or [4+3] formal cycloadducts of three classes. Cycloadditions of ynamides with 2H‐azirine species afford pyrrole products with two regioselectivities when the Cβ‐substituted 2H‐azirine is replaced from an alkyl (or hydrogen) with an ester group. For ynamides substituted with an electron‐rich phenyl group, their reactions with azidoalkenes proceed through novel [4+3] cycloadditions to deliver 1H‐benzo[d]azepine products instead. 相似文献
13.
Tetsuro Shimo Tsuneaki Iwakiri Kenichi Somekawa Takaaki Suishu 《Journal of heterocyclic chemistry》1992,29(1):199-201
Photosensitized cycloaddition reaction of methyl 2-pyrone-5-carboxylate ( 1 ) with 2,3-dihydrofuran gave cis- exo- and cis-endo-[2 + 2] cycloadducts across the C3-C4 double bond in 1 , and a [4 + 2] cycloadduct which was different in addition-orientation from the Diels-Alder adducts. Each [2 + 2] cycloadduct was obtained by the use of sensitizers having different triplet energies. Photosensitized reactions of 1 with 3,4-dihydro-2H-pyrans afforded cis-endo-[2 + 2] cycloadducts, respectively. The photocycloaddition mechanism was also explained from the excited state of 1 calculated by means of MNDO-Cl method. 相似文献
14.
A Novel N,P,C Cage Complex Formed by Rearrangement of a Tricyclic Phosphirane Complex: On the Importance of Non‐covalent Interactions
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Dr. Vitaly Nesterov Dr. Arturo Espinosa Dr. Gregor Schnakenburg Prof. Dr. Rainer Streubel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7010-7016
The reaction of Li/Cl P‐CPh3 phosphinidenoid tungsten(0) complex 2 with dimethylcyanamide afforded tricyclic phosphirane complex 4 , an unprecedented rearrangement of which led to the novel N,P,C cage complex 6 . On the basis of DFT calculations, formation and intramolecular [3+2] cycloaddition of the transient nitrilium phosphane ylide complex 3 to a phenyl ring of the triphenylmethyl substituent to give 4 is proposed. Furthermore, theoretical evidence for terminal N‐amidinophosphinidene complex 7 , formed by [2+1] cycloelimination from 4 , is provided, and the role of the electronic structure and non‐covalent interactions of intermediate 7 discussed. 相似文献
15.
Jinxiong Lin Dr. Friedrich Wossidlo. Dr. Nathan T. Coles Manuela Weber Dr. Simon Steinhauer Priv.-Doz. Dr. Tobias Böttcher Prof. Dr. Christian Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(7):e202104135
A phosphinine-borane adduct of a Me3Si-functionalized phosphinine and the Lewis acid B(C6F5)3 has been synthesized and characterized crystallographically for the first time. The reaction strongly depends on the nature of the substituents in the α-position of the phosphorus heterocycle. In contrast, the reaction of B2H6 with various substituted phosphinines leads to an equilibrium between the starting materials and the phosphinine–borane adducts that is determined by the Lewis basicity of the phosphinine. The novel phosphinine borane adduct ( 6 -B(C6F5)3) shows rapid and facile insertion and [4+2] cycloaddition reactivity towards phenylacetylene. A hitherto unknown dihydro-1-phosphabarrelene is formed with styrene. The reaction with an ester provides a new, facile and selective route to 1-R-phosphininium salts. These salts then undergo a [4+2] cycloaddition in the presence of Me3Si−C≡CH and styrene to cleanly form unprecedented derivatives of 1-R-phosphabarrelenium salts. 相似文献
16.
Antje Widmann Heike Kahlert Harm Wulff Fritz Scholz 《Journal of Solid State Electrochemistry》2005,9(5):380-389
Electrochemical reduction/oxidation cycles of immobilised powder mixtures of KCu[hcc] and KZn[hcf] as well as their mechanical milling lead to the formation of a quaternary solid solution (mixed crystals) with Cu2+ and Zn2+ on the nitrogen coordinated sites and Fe3+ and Co3+ on the carbon coordinated sites. The reaction products were studied by the X-ray diffractometry and voltammetric techniques. The formation of solid solutions of the general formula KCuxZn1-x[hcc]x[hcf]1-x is the first example of an electrochemical and mechanochemical reaction leading to mixed hexacyanometalates.Dedicated to Professor Dr. G. Horányi on the occasion of his 70th birthday. 相似文献
17.
In the presence of a catalytic amount of GaCl3, dimethyl 2‐(naphthalen‐1‐yl)cyclopropane‐1,1‐dicarboxylate 5 undergoes selective [3+2]‐annulation‐type dimerization to give a polysubstituted cyclopentane containing two naphthalenyl substituents in the vicinal position (Scheme 2). Treatment of the same cyclopropane with an equimolar amount of GaCl3?THF results in dimerization with electrophilic attack on each of the benzene rings to give [3+3] and [3+4] annulation products. The latter represent a new type of dimerization of donor? acceptor cyclopropanes. Finally, under conditions of double catalysis with GaCl3, 3,3,5,5‐tetrasubstituted 4,5‐dihydropyrazole, this cyclopropane‐dicarboxylate undergoes stereospecific dimerization as a result of electrophilic ipso‐attack to give a tetracyclic pentaleno[6a,1‐a]naphthalene derivative (Scheme 5). Possible reaction mechanisms are proposed. 相似文献
18.
The synthesis of the ligand, m-12N3O-dimer (1,3-bis(1-oxa-4,7,10-triazacyclododecan-7-yl)methyl)benzene, L), and the stability and hydrolysis constants of its dinuclear Zn(II) and Cu(II) complexes are reported, in addition to the effect of pH on HPNP (2-hydroxypropyl-4-nitrophenylphosphate) hydrolysis reaction rates promoted by these complexes. Various structural possibilities of the [Zn2L] and [Cu2L] hydrolytic species derived from solution equilibrium modeling are predicted from density functional theory (DFT) studies to correlate with the promoted HPNP hydrolysis reaction rates and to establish the structure–function–reactivity relationship. Upon deprotonation [Zn2L(OH)]3+ tends to form a structure with a “closed-form” conformation where it is not possible for para-isomers. At pH >8, the formation of the closed-form [Zn2L(OH)2]2+ and [Zn2L(μ-OH)(OH)2]+ species led to faster promoted HPNP hydrolysis rates than the [Zn2L(OH)]3+ species. On the other hand, the observed rates of the Cu2L-promoted HPNP hydrolysis reaction were much slower than those of the [Zn2L]-promoted ones due to formation of the inactive, di-μ-OH? bridged closed-form [Cu2L(μ-OH)2]2+ structure at high pH. The effects of solvent molecules and the use of higher DFT computation levels, i.e., M06 and M06–2X, in conjunction with cc-pVDZ and cc-pVTZ basis sets on the DFT-predicted structures for both [Cu(12N4)(H2O)]2+ and [Zn(12N3O)(H2O)2]2+ complexes were also evaluated and compared with those using the B3LYP/6–31G* method. 相似文献
19.
In chloroform, [ZrCl4·2(MeO)3PO] exists in both cis- and trans-isomeric forms. Three reactions can be envisaged in the presence of excess (MeO)3PO = L: (1) cis-[ZrCl4·2L] + *L?cis-[ZrCl4·L*L]+ L; (2) trans-[ZrCl4·2L] + *L ? trans-[ZrCl4·L*L] + L; (3) cis-[ZrCl4·2L]? trans-[ZrCl4·2L]. To distinguish between these possible reaction pathways, we have used 2D 1H-NMR spectroscopy. For the first time, variable-pressure 2D exchange spectra were used for mechanistic assignments. cis/trans-Isomerisation was found to be the fastest reaction (in CHCl3/CDCl3), with a small acceleration at higher pressure: it is concluded to be an intramolecular process with a slightly contracted six-coordinate transition state. The intermolecular (MeO)3PO exchange on the cis- and trans-isomer are second-order processes and are strongly accelerated by increased pressure: Ia mechanisms are suggested without ruling out limiting A mechanisms. 相似文献
20.
Bin Peng Hui Chao Bin Sun Feng Gao Liang-Nian Ji Jian Zhang 《Transition Metal Chemistry》2007,32(2):271-277
Two novel cobalt(III) mixed-polypyridyl complexes
[Co(bpy)2(dpta)]3+ and [Co(bpy)2(amtp)]3+ (bpy = 2,2′-bipyridine, dpta = dipyrido-[3,2-a;2′,3′-c]-thien-[3,4-c]azine, amtp = 3-amino-1,2,4-triazino[5,6-f]-1,10-phenanthroline)
have been synthesized and characterized. The interaction of CoIII complexes with calf thymus DNA was investigated by spectroscopic and viscosity measurements. Results suggest that the two
complexes bind to DNA via an intercalative mode. Moreover, CoIII complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The mechanism studies
reveal that hydroxyl radical (OH•) is likely to be the reactive species responsible for the cleavage of plasmid DNA by [Co(bpy)2(dpta)]3+ and superoxide anion radical (O
2
•−
) acts as the key role in the cleavage reaction of plasmid DNA by [Co(bpy)2(amtp)]3+. 相似文献