共查询到20条相似文献,搜索用时 29 毫秒
1.
Eberhard Reimann Fritz Grasberger Kurt Polborn 《Monatshefte für Chemie / Chemical Monthly》2003,134(7):991-1014
Summary. Certain benzylated oxazoloisoquinolinones readily available from Reissert compounds provided an efficient access to 8-oxoprotoberberines in three steps. A series of these new precursors as well as
several oxoprotoberberines were prepared and the scope and limitation of this procedure were investigated.
Corresponding author. E-mail: ebrei@cup.uni-muenchen.dem
Part of PhD thesis, LMU München, D
Received October 31, 2002; accepted November 5, 2002
Published online May 6, 2003 相似文献
2.
E. Siliņa J. Ashaks S. Belyakov A. Tokmakov L. Pech D. Zaruma 《Chemistry of Heterocyclic Compounds》2007,43(12):1582-1588
Bismuth 8-quinolineselenolate Bi(C9H6NSe)3 was synthesized. The molecular and crystal structure of this compound was determined by X-ray diffraction structural analysis.
The effect of replacing the ligand atoms Se→S and the role of the unshared electron pair on the formation of the coordination
polyhedron of the central bismuth atom in bismuth(III) 8-quinolineselenolate and bismuth(III) 8-quinolinethiolate, which are
complexes of a Group V p-element in an incomplete valence state was discussed.
Dedicated to the memory of Academician Yurii Bankovsky, the founder of the chemistry of 8-mercaptoquinoline (December 22,
1927–January 28, 2003) on the occasion of the eightieth anniversary of his birth.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1866–1874, December, 2007. 相似文献
3.
Palladium‐Catalyzed Construction of Heteroatom‐Containing π‐Conjugated Systems by Intramolecular Oxidative CH/CH Coupling Reaction 下载免费PDF全文
Kenta Saito Dr. Prasanna Kumara Chikkade Prof. Dr. Motomu Kanai Prof. Dr. Yoichiro Kuninobu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8365-8368
Synthesis of heteroatom‐containing ladder‐type π‐conjugated molecules was successfully achieved via a palladium‐catalyzed intramolecular oxidative C?H/C?H cross‐coupling reaction. This reaction provides a variety of π‐conjugated molecules bearing heteroatoms, such as nitrogen, oxygen, phosphorus, and sulfur atoms, and a carbonyl group. The π‐conjugated molecules were synthesized efficiently, even in gram scale, and larger π‐conjugated molecules were also obtained by a double C?H/C?H cross‐coupling reaction and successive oxidative cycloaromatization. 相似文献
4.
Haisheng Wang Yan Zhang Wei Ye Stewart W. Schneller 《Journal of heterocyclic chemistry》2015,52(4):1132-1135
The synthesis of new members of the aristeromycin and neplaoncin A families of carbocyclic nucleosides possessing the 1H‐pyrazolo[3,4‐d]pyrimidine ring is reported. For this purpose, an adapted route to 4‐amino‐1H‐pyrazolo[3,4‐d]pyrimidine is described. 相似文献
5.
A Comparative Study of 8‐Hydroxyquinoline and 8‐Hydroxyquinoline‐5‐sulfonic Acid for Antimony(III) Determination by AdSV. Substituent Effect on Sensitivity II 下载免费PDF全文
A sensitive and selective method for the determination of Sb3+ based on the formation of its complexes with 8‐hydroxyquinoline (HQ) and 8‐hydroxyquinoline‐5‐sulfonic acid (HQS) is proposed. The best analytical conditions are: pH 5.4 and 2.2 for HQ and HQS, respectively; CHQ from 15.0 to 25.0 µmol L?1 and CHQS from 70.0 to 200.0 µmol L?1. The detection limits are 100.0 and 14.0 ng L?1 (tacc=30 s) for Sb3+ with HQ and HQS, respectively. The method using HQS as ligand has a 2.2‐fold higher sensitivity than that with HQ and the former was chosen for Sb3+ determination. 相似文献
6.
Xiaoge Yang Zhuqing Liu Prof. Chenglin Sun Prof. Dr. Jiping Chen Prof. Dr. Zhengkun Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14085-14094
Efficient palladium‐catalyzed cross‐coupling reactions of the internal olefins α‐cyanoketene dithioacetals with a variety of olefins were achieved in dioxane/HOAc/DMSO (9:3:1 v/v/v) under air atmosphere or by means of AgOAc as the terminal oxidant. Electron‐deficient terminal olefins reacted to form the linear diene derivatives with air as the oxidant. Styrenes underwent the cross‐coupling to give both the linear and branched dienes when using AgOAc as the oxidant. Unactivated cyclic and linear internal olefin substrates both reacted in the presence of a catalytic amount of benzoquinone in air to produce skipped dienes. The typical products were structurally confirmed by X‐ray crystallography. 相似文献
7.
The Role of Weak Interactions in the Mechano‐induced Single‐Crystal‐to‐Single‐Crystal Phase Transition of 8‐Hydroxyquinoline‐Based Co‐crystals 下载免费PDF全文
Jie Liu Dr. Guangfeng Liu Prof. Dr. Yang Liu Xiaoxin Zheng Quanxiang Han Xin Ye Prof. Dr. Xutang Tao 《化学:亚洲杂志》2016,11(11):1682-1687
Mechano‐induced single‐crystal‐to‐single‐crystal (SCSC) phase transitions in crystalline materials that change their properties have received more and more attention. However, there are still too few examples to study molecular‐level mechanisms in the mechano‐induced SCSC phase transitions, making the systematic and in‐depth understanding very difficult. We report that bis‐(8‐hydroxyquinolinato) palladium(II)‐tetracyanoquinodimethane (PdQ2‐TCNQ) and bis‐(8‐hydroxyquinolinato) copper(II)‐tetracyanoquinodimethane (CuQ2‐TCNQ) show very different mechano‐response behaviors during the SCSC phase transition. Phase transition in CuQ2‐TCNQ can be triggered by pricking on the crystal surface, while in PdQ2‐TCNQ it can only be induced by applying pressure uniformly over the whole crystal face. The crystallography data and Hirshfeld surface analysis indicate that the weak intra‐layer C?H???O, C?H???N hydrogen bonds and inter‐layer stacking interactions determine the feasibility of the SCSC phase transition by mechanical stimuli. Weaker intra‐layer interactions and looser inter‐layer stacking make the SCSC phase transition occur much more easily in the CuQ2‐TCNQ. 相似文献
8.
Dr. Dhananjayan Vasu Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(24):7162-7166
Two new palladium‐catalyzed reactions of aromatic sulfur compounds enabled the conversion of dibenzothiophenes into triphenylenes in four steps. This transformation of one aromatic framework into another consists of 1) 4‐chlorobutylation of the dibenzothiophene to form the corresponding sulfonium salt, 2) palladium‐catalyzed arylative ring opening of the sulfonium salt with a sodium tetraarylborate, 3) an intramolecular SN2 reaction to form a teraryl sulfonium salt, and 4) palladium‐catalyzed intramolecular C? S/C? H coupling through electrophilic palladation. Symmetrical as well as unsymmetrical triphenylenes of interest were synthesized in a tailor‐made fashion in satisfactory overall yields. 相似文献
9.
10.
Jrg Gloede Sigrid Ozegowski Iris Keitel Klaus Buttke Margit Gruner Burkhard Costisella Wolfgang Pritzkow Holger Stephan Michael Bartoschek 《无机化学与普通化学杂志》2006,632(1):123-132
Two‐ and Threefold Intramolecular Brigdging p‐tert‐Butylcalix[8]arene Triphosphates – Synthesis, Structure and Stereochemistry [1] The phosphorylation of p‐tert‐butylcalix[8]arene ( 1 ) with phosphorus pentachloride and hydrolysis gives intramolecular bridging tert‐butylcalix[8]arene triphosphates. The reactivity (esterification, dehydratisation, complexation), the structure (nmr and x‐ray), and the stereochemical behaviour of the phosphates will be discussed. 相似文献
11.
Dr. Brian N. Laforteza Kelvin S. L. Chan Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2015,54(38):11143-11146
The commonly used para‐nitrobenzenesulfonyl (nosyl) protecting group is employed to direct the C? H activation of amines for the first time. An enantioselective ortho‐C? H cross‐coupling between nosyl‐protected diarylmethylamines and arylboronic acid pinacol esters has been achieved utilizing chiral mono‐N‐protected amino acid (MPAA) ligands as a promoter. 相似文献
12.
Efficient Synthesis of 1,2,3‐Triazoles by Copper‐Mediated CN and NN Bond Formation Starting From N‐Tosylhydrazones and Amines 下载免费PDF全文
Zhengkai Chen Qiangqiang Yan Hong Yi Zhanxiang Liu Prof. Dr. Aiwen Lei Prof. Dr. Yuhong Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13692-13697
An effective copper‐mediated synthesis of 1,5‐dialkyl‐4‐aryl‐1,2,3‐triazoles and 1,4‐dialkyl‐5‐aryl‐1,2,3‐triazoles has been achieved by the use of different N‐tosylhydrazones and alkyl amines. The scope of the substrates could be extended from anilines to aliphatic amines when 30 mol % amino acid is added into the reaction mixture. This methodology exhibits many notable features, such as broad substrates scope, high efficiency, and good regioselectivity. Preliminary mechanistic studies indicated that the reaction probably proceeded through a 1‐tosyl‐2‐vinyldiazene intermediate and subsequent aza‐Michael addition and N?N bond formation process. 相似文献
13.
Palladium‐Catalyzed Zinc‐Amide‐Mediated CH Arylation of Fluoroarenes and Heteroarenes with Aryl Sulfides 下载免费PDF全文
Shinya Otsuka Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14703-14707
C?H arylation of polyfluoroarenes and heteroarenes with aryl sulfides proceeds smoothly with the aid of a palladium–N‐heterocyclic carbene catalyst. A bulky zinc amide, TMPZnCl ? LiCl, plays a key role as an effective base to generate the corresponding arylzinc species in situ. This arylation protocol is practically much easier to perform than our previous method, which necessitates preparation of the arylzinc reagents in advance from the corresponding aryl halides. Aryl sulfides that are prepared through sulfur‐specific reactions, such as SNAr sulfanylation and extended Pummerer reactions, undergo this direct arylation, offering interesting transformations that are otherwise difficult to achieve with conventional halogen‐based organic synthesis. 相似文献
14.
Dr. Amanda Sølvhøj Andreas Ahlburg Prof. Dr. Robert Madsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(45):16272-16279
A new coupling reaction has been developed in which β‐bromostyrenes react with ethers and tertiary amines to introduce the styryl group in the α‐position. The transformation is mediated by Me2Zn/O2 with 10 % MnCl2 and is believed to proceed by a radical addition–elimination mechanism. The ether and the amine are employed as solvent and the coupling takes place through the most stable α radical for unsymmetrical substrates. The products are obtained in moderate to good yields as the pure E isomers. The coupling can be achieved with a range of smaller cyclic and acyclic ethers/amines as well as various substituted β‐bromostyrenes. 相似文献
15.
Mechanistic Study on Rh‐Catalyzed Stereoselective CC/CH Activation of tert‐Cyclobutanols 下载免费PDF全文
Dr. Haizhu Yu Dr. Chen Wang Yimeng Yang Prof. Zhi‐Min Dang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3839-3848
A mechanistic study was performed on the Rh‐catalyzed stereoselective C?C/C?H activation of tert‐cyclobutanols. The present study corroborated the previous proposal that the reaction occurs by metalation, β‐C elimination, 1,4‐Rh transfer, C?O insertion, and a final catalyst‐regeneration step. The rate‐determining step was found to be the 1,4‐Rh transfer step, whereas the stereoselectivity‐determining step did not correspond to any of the aforementioned steps. It was found that both the thermodynamic stability of the product of the β‐C elimination and the kinetic feasibility of the 1,4‐Rh transfer and C?O insertion steps made important contributions. In other words, three steps (i.e., β‐C elimination, 1,4‐Rh transfer, and C?O insertion) were found to be important in determining the configurations of the two quaternary stereocenters. 相似文献
16.
Rhodium‐Catalyzed Annulative Coupling of 3‐Phenylthiophenes with Alkynes Involving Double C‐H Bond Cleavages 下载免费PDF全文
Tomonori Iitsuka Dr. Koji Hirano Prof. Dr. Tetsuya Satoh Prof. Dr. Masahiro Miura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):385-389
Double C?H bond activation took place efficiently upon treatment of 3‐phenylthiophenes with alkynes in the presence of a rhodium catalyst and a copper salt oxidant to form the corresponding naphthothiophene derivatives. Dehydrogenative coupling with alkenes was also found to occur on the phenyl moiety rather than the thiophene ring. These reactions provide straightforward synthetic methods for π‐conjugated molecules involving a thiophene unit from readily available, simple building blocks. 相似文献
17.
Activation of Strong Boron–Fluorine and Silicon–Fluorine σ‐Bonds: Theoretical Understanding and Prediction 下载免费PDF全文
Dr. Hajime Kameo Prof. Shigeyoshi Sakaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13588-13597
The oxidative addition of BF3 to a platinum(0) bis(phosphine) complex [Pt(PMe3)2] ( 1 ) was investigated by density functional calculations. Both the cis and trans pathways for the oxidative addition of BF3 to 1 are endergonic (ΔG°=26.8 and 35.7 kcal mol?1, respectively) and require large Gibbs activation energies (ΔG°≠=56.3 and 38.9 kcal mol?1, respectively). A second borane plays crucial roles in accelerating the activation; the trans oxidative addition of BF3 to 1 in the presence of a second BF3 molecule occurs with ΔG°≠ and ΔG° values of 10.1 and ?4.7 kcal mol?1, respectively. ΔG°≠ becomes very small and ΔG° becomes negative. A charge transfer (CT), F→BF3, occurs from the dissociating fluoride to the second non‐coordinated BF3. This CT interaction stabilizes both the transition state and the product. The B?F σ‐bond cleavage of BF2ArF (ArF=3,5‐bis(trifluoromethyl)phenyl) and the B?Cl σ‐bond cleavage of BCl3 by 1 are accelerated by the participation of the second borane. The calculations predict that trans oxidative addition of SiF4 to 1 easily occurs in the presence of a second SiF4 molecule via the formation of a hypervalent Si species. 相似文献
18.
Confusing Quantitative Descriptions of BrønstedLowry AcidBase Equilibria in Chemistry Textbooks – A Critical Review and Clarifications for Chemical Educators 下载免费PDF全文
Erich C. Meister Martin Willeke Werner Angst Antonio Togni Peter Walde 《Helvetica chimica acta》2014,97(1):1-31
In chemistry textbooks, the pK value of water in the solvent water at 25 °C is sometimes given as 14.0, sometimes as 15.7. This is confusing. The particular chemical reaction considered is the one in which water as Brønsted? Lowry acid reacts with water as Brønsted? Lowry base in water as solvent to yield equal concentrations of hydrated oxonium and hydroxide ions, H3O+(aq) and HO?(aq), respectively. This reaction is also known as the ‘self‐ionization’ of water for which the equilibrium constant is abbreviated as Kw with its known value of 10?14.0 at 25 °C, i.e., pKw(25 °C)=14.0. Identical values for pK and pKw at a fixed temperature appear reasonable, since K and Kw refer to one and the same reaction. Therefore, reasons for the apparent disagreement between the ‘thermodynamically correct’ pKa value for water (14.0 at 25 °C) and the value reported in most organic chemistry textbooks (15.7) should be discussed when teaching acid? base chemistry. There are good arguments for introducing, from the very beginning, the concepts of activity and thermodynamic standard states when teaching quantitative aspects of chemical equilibria. This also explains in a straightforward way why all thermodynamic equilibrium constants, including Kw, are dimensionless, and why pK(25 °C)=0. 相似文献
19.
Rhodium(III)‐Catalyzed CH Activation and Indole Synthesis With Hydrazone as an Auto‐Formed and Auto‐Cleavable Directing Group 下载免费PDF全文
Liyao Zheng Prof. Dr. Ruimao Hua 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2352-2356
An efficient, practical, and external‐oxidant‐free indole synthesis from readily available aryl hydrazines was developed, by using hydrazone as a directing group for RhIII‐catalyzed C?H activation and alkyne annulation. The hydrazone group was formed by in situ condensation of hydrazines and C?O source, whereas its N?N bond was served as an internal oxidant, for which we termed it as an auto‐formed and auto‐cleavable directing group (DGauto). This method needs no step for pre‐installation and post‐cleavage of the directing group, making it a quite easily scalable approach to access unprotected indoles with high step economy. The DGauto strategy was also applicable for isoquinoline synthesis. In addition, synthetic utilities of this chemistry for rapid assembly of π‐extended nitrogen‐doped polyheterocycles and bioactive molecules were demonstrated. 相似文献
20.
Palladium‐Catalyzed/Norbornene‐Mediated CH Activation/ N‐Tosylhydrazone Insertion Reaction: A Route to Highly Functionalized Vinylarenes 下载免费PDF全文
Dr. Ping‐Xin Zhou Lan Zheng Jun‐Wei Ma Yu‐Ying Ye Xue‐Yuan Liu Prof. Dr. Peng‐Fei Xu Prof. Dr. Yong‐Min Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6745-6751
A straightforward method for the synthesis of highly functionalized vinylarenes through palladium‐catalyzed, norbornene‐mediated C?H activation/carbene migratory insertion is described. Extension to a one‐pot procedure is also developed. Furthermore, this method can also be used to generate polysubstituted bicyclic molecules. The reaction proceeds under mild conditions to give the products in satisfactory yields using readily available starting materials. This is a Catellani–Lautens reaction that incorporates different types of coupling partners. Additionally, this reaction is the first to demonstrate the possibility of combining Pd‐catalyzed insertion of diazo compounds and Pd‐catalyzed C?H activation. 相似文献