- Addition of benzyl ethers to alkynes: A metal-free synthesis of 1: H -isochromenes
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Bromotrimethylsilane (TMSBr)-promoted intramolecular cyclization of (o-arylethynyl)benzyl ethers to form 1H-isochromenes at room temperature is reported. Further studies indicated that vinyl carbocations are the reaction intermediates which are stabilized by the conjugated aryl groups. Thus, O-addition of benzyl ethers/tetrahydropyrans to alkynes was achieved under metal-free, acidic conditions. These reaction conditions were compatible with an alkynyl Prins reaction; therefore, 1H-isochromenes were produced directly from alkynyl benzaldehydes and alkynyl alcohols using a one-pot procedure. This journal is
- Chen, Cheng-Chun,Hou, Duen-Ren,Kotipalli, Trimurtulu,Kuan, Tzu-Hsuan
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p. 10390 - 10402
(2021/12/17)
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- Synthesis of N-Heterocyclic Carbine Silver(I) and Palladium(II) Complexes with Acylated Piperazine Linker and Catalytic Activity in Three Types of C—C Coupling Reactions
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Two bis-imidazolium salts LH2·Cl2 and LH2·(PF6)2 with acylated piperazine linker and two N-heterocyclic carbene (NHC) silver(I) and palladium(II) complexes [L2Ag2](PF6)2 (1) and [L2Pd2Cl4] (2) were prepared. The crystal structures of LH2·Cl2 and 1 were confirmed by X-ray analysis. In 1, one 26-membered macrometallocycle was generated through two silver(I) ions and two bidentate ligands L. The catalytic activity of 2 was investigated in Sonogashira, Heck-Mizoroki and Suzuki-Miyaura reactions. The results displayed that these C—C coupling reactions can be smoothly carried out under the catalysis of 2.
- Liu, Qingxiang,Zhang, Xiantao,Zhao, Zhixiang,Li, Xinying,Zhang, Wei
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supporting information
p. 605 - 613
(2021/02/01)
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- Tunable Synthesis of Indeno[1,2- c]furans and 3-Benzoylindenones via FeCl3-Catalyzed Carbene/Alkyne Metathesis Reaction of o-Alkynylbenzoyl Diazoacetates
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An efficient synthesis of indeno[1,2-c]furan and 3-benzoylindenone derivatives through a FeCl3-catalyzed carbene/alkyne metathesis reaction of o-alkynylbenzoyl diazoacetates is presented. Mechanistically, the key intermediate, vinyl iron carbene, is formed by 5-exo-dig carbocyclization and terminated with a formal [3 + 2] cycloaddition or carbonylation. To the best of our knowledge, this is the first example in which FeCl3 is used as a catalyst for a carbene/alkyne metathesis reaction. Finally, derivatization reactions were carried out to showcase the value of the products.
- Li, Bin,Shen, Nana,Yang, Yujie,Zhang, Xinying,Fan, Xuesen
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supporting information
p. 388 - 393
(2021/01/13)
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- Facile preparation of 3-aryl-4-iodoisoquinolines from N-(o-Arylethynyl)benzyl p-toluenesulfonamides with iodine and base
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Treatment of N-(o-arylethynyl)benzyl p-toluenesulfonamides with molecular iodine in the presence of NaHCO3 at 60 °C, followed by the reaction with tBuOK at room temperature gave 3-aryl-4-iodoisoquinolines in good yields. 4-Iodo-3-phenylisoquinoline, which is one of the obtained 3-aryl-4-iodoisoquinolines, was further transformed into isoquinoline derivatives smoothly. The present approach is a novel one-pot method for the preparation of 3-aryl-4-iodoisoquinolines from N-(o-arylethynyl)benzyl p-toluenesulfonamides under transition-metal-free conditions.
- Naruto, Hiroki,Togo, Hideo
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- Gold Catalysis Meets Materials Science – A New Approach to π-Extended Indolocarbazoles
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Herein we describe a modular, convergent synthesis of substituted benzo[a]benzo[6,7]-indolo[2,3-h]carbazoles (BBICZs) using a bidirectional gold-catalyzed cyclization reaction as a key step. A building block strategy enabled the easy variation of substituents at different positions of the core structure and a general analysis of substitution effects on the materials properties of the target compounds. All BBICZs were fully characterized and their optical and electronic properties were studied experimentally as well as by computational methods. Organic thin-film transistors based on eight selected derivatives were fabricated by vacuum deposition and charge-carrier mobilities up to 1 cm2/Vs were measured. (Figure presented.).
- Hendrich, Christoph M.,Bongartz, Lukas M.,Hoffmann, Marvin T.,Zschieschang, Ute,Borchert, James W.,Sauter, Désirée,Kr?mer, Petra,Rominger, Frank,Mulks, Florian F.,Rudolph, Matthias,Dreuw, Andreas,Klauk, Hagen,Hashmi, A. Stephen K.
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supporting information
p. 549 - 557
(2020/12/07)
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- Palladium-Catalyzed Aminomethylative Oppolzer-Type Cyclization of Enynes: Access to Aminomethylated Benzofulvenes
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A novel palladium-catalyzed Oppolzer-type cyclization reaction aided by the aminomethyl cyclopalladated complex has been developed, which provides rapid access to functionalized benzofulvenes with excellent stereoselectivity. The corresponding products can undergo Diels–Alder reaction with maleimides, providing a series of complex polycyclic compounds with excellent regio- and stereoselectivities.
- Huang, Hanmin,Huang, Renbin,Li, Renren,Yu, Bangkui
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supporting information
p. 9510 - 9515
(2021/12/14)
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- Ruthenabenzene: A Robust Precatalyst
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Metallaaromatics constitute a unique class of aromatic compounds where one or more transition metal elements are incorporated into the aromatic system, the parent of which is metallabenzene. One of the main concerns about metallabenzenes generally deals with the structural characterization related to their relative aromaticity compared to the carbon archetype. Transition metal-containing metallabenzenes are also implicated in certain catalytic processes such as alkyne metathesis polymerization; however, these transition metal-based metallaaromatic compounds have not been developed as a catalyst. Herein, we describe an effective strategy to generate diverse arrays of ruthenabenzenes and demonstrated them as an aromatic equivalent of the Grubbs-type ruthenium alkylidene catalysts. These ruthenabenzenes can be prepared via an enyne metathesis and metallotropic [1,3]-shift cascade process to form alkyne-chelated ruthenium alkylidene intermediates followed by spontaneous cycloaromatization. The aromatic nature of these complexes was confirmed by spectroscopic and X-ray crystallographic data, and the mechanistic pathways for the cycloaromatization process were studied by DFT calculations. These ruthenabenzenes display robust catalytic activity for metathesis and other transformations, which illustrates that metallabenzenes are not only compounds of structural and theoretical interests but also are a novel platform for new catalyst development.
- Gupta, Saswata,Su, Siyuan,Zhang, Yu,Liu, Peng,Wink, Donald J.,Lee, Daesung
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supporting information
p. 7490 - 7500
(2021/05/26)
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- Alumina-Mediated π-Activation of Alkynes
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The ability to induce powerful atom-economic transformation of alkynes is the key feature of carbophilic π-Lewis acids such as gold- and platinum-based catalysts. The unique catalytic activity of these compounds in electrophilic activations of alkynes is explained through relativistic effects, enabling efficient orbital overlapping with π-systems. For this reason, it is believed that noble metals are indispensable components in the catalysis of such reactions. In this study, we report that thermally activated γ-Al2O3activates enynes, diynes, and arene-ynes in a manner enabling reactions that were typically assigned to the softest π-Lewis acids, while some were known to be triggered exclusively by gold catalysts. We demonstrate the scope of these transformations and suggest a qualitative explanation of this phenomenon based on the Dewar-Chatt-Duncanson model confirmed by density functional theory calculations.
- Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
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supporting information
p. 15420 - 15426
(2021/09/30)
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- Catalytic Asymmetric Tandem Reaction of o-Alkynylbenzaldehydes, Amines, and Diazo Compounds
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An efficient asymmetric tandem reaction of o-alkynylbenzaldehydes, amines, and diazo compounds catalyzed by chiral silver imidodiphosphate has been established. Chiral 1,2-dihydroisoquinoline analogues have a tertiary stereocenter at the C1 position, and substituents at the C3 position are available with up to 97% yields and 98% ee. These products can be elaborated into the corresponding β-aminophosphonates or PARP1-inhibitor analogues.
- Wu, Wei,Liao, Na,Wei, Qi,Huang, Jiaying,Huang, Qi,Peng, Yungui
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supporting information
p. 6872 - 6876
(2021/09/14)
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- Synthetic method 1-2 -dihydrocyclobutene [a] naphthalene derivative and precursor thereof
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The invention relates to the field of organic synthetic chemistry, in particular to a 1,2-dihydrocyclobuteno[a] naphthalene derivative and a synthesis method of a precursor thereof. The invention provides a synthesis method of allenic ketone ester. According to the synthesis method, benzene ring-connected dieneyne ketone ester is synthesized for the first time; the dieneyne ketone ester is the precursor for synthesizing the 1,2-dihydrocyclobuteno[a] naphthalene, and has the advantages of being simple, convenient, efficient, mild in reaction condition, environmentally friendly, low in cost, low energy in consumption and the like.
- -
-
Paragraph 0058-0061
(2020/10/04)
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- Synthesis of organoselenyl isoquinolinium imidesviairon(iii) chloride-mediated tandem cyclization/selenation ofN′-(2-alkynylbenzylidene)hydrazides and diselenides
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This report describes the synthesis of organoselenyl isoquinolinium imides through a tandem cyclization betweenN′-(2-alkynylbenzylidene)hydrazides and diselenides. The reaction was carried out at room temperature under an ambient atmosphere using cheap iron(iii) chloride as the metallic source. The strategy shows good tolerance to a broad range ofN′-(2-alkynylbenzylidene)hydrazides and diselenides, and forms C-N and C-Se bonds in one step. The obtained product is further transformed into a bioactiveH-pyrazolo[5,1-a]isoquinoline skeleton easilyviaa silver catalyzed [3 + 2] cycloaddition.
- Cai, Zhong-Jian,Ji, Shun-Jun,Li, Fang-Hui,Wang, Dian-Liang,Wu, Bing,Yao, Hai-Feng
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supporting information
p. 7577 - 7584
(2020/10/14)
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- HETEROCYCLIC COMPOUND AND ORGANIC LIGHT EMITTING DEVICE COMPRISING SAME
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The present specification relates to a heterocyclic compound represented by Chemical Formula 1, and an organic light emitting device comprising the same.
- -
-
Paragraph 0136; 0137; 014
(2020/11/24)
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- Regio- and stereoselective intramolecular hydroalkoxylation of aromatic alkynols: an access to dihydroisobenzofurans under transition-metal-free conditions
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An efficient, transition-metal-free method to synthesize dihydroisobenzofuran derivatives via intramolecular hydroalkoxylation of aromatic alkynols with the promotion of cesium carbonate has been developed. The reaction proceeds regioselectively with exclusive formation of 5-exo-dig product, and only Z-isomer of the new generated double bond is observed. This new protocol features with milder reaction conditions, more convenient operation and satisfactory selectivities.
- Yu, Shu-Yan,Gao, Li-Hong,Wu, Jing-Xin,Lan, Hong-Bing,Ma, Yi,Yin, Zhi-Gang
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p. 3303 - 3310
(2020/04/27)
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- In situ air oxidation and photophysical studies of isoquinoline-fused N-heteroacenes
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An efficient, metal free and environment friendly synthesis of isoquinoline-fused benzimidazole has been developed via in situ air oxidation. Also, syntheses of isoquinoline-fused quinazolinone heteroacenes were successfully achieved. The synthesized isoquinoline-fused benzimidazole and isoquinoline-fused quinazolinone derivatives showed λmax, Fmax and Φf values in the ranges 356-394 nm, 403-444 nm and 0.063-0.471, respectively, in CHCl3,.
- Koketsu, Mamoru,Ninomiya, Masayuki,Sonawane, Amol D.,Sonawane, Rohini A.,Win, Khin Myat Noe
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p. 2129 - 2138
(2020/03/27)
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- Catalytic asymmetric three-component reaction of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate
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An efficient enantioselective synthesis of cyclic α-aminophosphonates via multicomponent reactions of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate has been developed with the use of a chiral silver spirocyclic phosphate as the catalyst. This protocol provides straightforward access to a series of chiral C1-phosphonylated 1,2-dihydroisoquinoline derivatives with high yields (up to 99%) and high enantioselectivities (up to 94% ee) for a broad substrate scope. The products could be further transformed into densely functionalized compounds and corresponding α-aminophosphonic acids.
- Zou, Liangliang,Huang, Jiaying,Liao, Na,Liu, Yan,Guo, Qixiang,Peng, Yungui
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supporting information
p. 6932 - 6937
(2020/09/15)
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- (E)-N-(pyren-1-ylmethylene)benzenamine: efficient promoter for additive-free palladium catalyzed aerobic oxidative coupling of arylboronic acids and terminal alkynes
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Abstract: A highly productive protocol for the synthesis of internal alkynes by the carbon–carbon cross-coupling reactions of electronically different arylboronic acids with substituted phenylacetylenes was described by employing (E)-N-(pyren-1-ylmethylene)benzenamine with Pd(OAc)2. The influence of reaction parameters such as solvent, base and reaction temperature in this carbon–carbon cross-coupling reaction was also investigated. The substrate scope could be expanded to electron-poor alkynes, for which the conventional Sonogashira reaction gives poor yields. Moderate to excellent yield was obtained in the oxidative Sonogashira-type coupling reaction. Graphic abstract: [Figure not available: see fulltext.]
- Lakshmipraba, Jagadeesan,Prabhu, Rupesh Narayana,Dhayabaran, Victor Violet
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p. 3661 - 3669
(2020/04/21)
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- Anthracen-9-ylmethylene-(4-methoxyphenyl)amine: efficient promoter for silver-free palladium-catalyzed aerobic oxidative Sonogashira reactions
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An efficient protocol for the synthesis of unsymmetrical substituted diarylacetylenes by the C(sp2)–C(sp) cross-coupling reactions of substituted phenylacetylenes and electronically different arylboronic acids has been developed. Anthracen-9-ylmethylene-(4-methoxyphenyl)amine was employed as an efficient promoter in this Pd(OAc)2-catalyzed oxidative Sonogashira reaction in air in the absence of silver salt under optimized reaction conditions. The impact of reaction parameters such as solvent, base, reaction temperature and time in this silver-free aerobic oxidative Sonogashira cross-coupling reaction was also evaluated. Electron-deficient phenylacetylenes, which are sluggish coupling partners in the traditional Sonogashira reaction, underwent coupling in this protocol. The catalytic system is inexpensive, effortlessly attainable and highly flexible for functionalized phenylacetylenes and arylboronic acids. Graphic abstract: [Figure not available: see fulltext.].
- Lakshmipraba, Jagadeesan,Prabhu, Rupesh Narayana,Dhayabaran, Victor Violet
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p. 325 - 331
(2020/04/15)
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- Carbonyl-Directed Addition of N-Alkylhydroxylamines to Unactivated Alkynes: Regio- and Stereoselective Synthesis of Ketonitrones
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A variety of ketonitrones were synthesized in moderate to excellent yields with high chemo-, regio-, and stereoselectivity by using carbonyl-directed addition of N-alkylhydroxylamines to unactivated alkynes under mild conditions. The product diverisity could be controlled by the use of different bases, and EtN(n-Pr)2 could promote the formation of ketonitrones while using EtONa as base led to indanone-derived nitrones. Control experiments indicated that the carbonyl group of the substrate acted as an H-bond acceptor except for an electron-withdrawing group, and conjugated enone skeleton accounted for the high selectivity.
- Liu, Yilin,Feng, Xiangqing,Liu, Yanyun,Lin, Hongwei,Li, Yuanxiang,Gong, Yingying,Cao, Lei,Chen, Liping
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supporting information
p. 382 - 386
(2019/01/11)
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- Realization of Highly Efficient Red Phosphorescence from Bis-Tridentate Iridium(III) Phosphors
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Bis-tridentate Ir(III) metal complexes bring forth interesting photophysical properties, among which the orthogonal arranged, planar tridentate chelates could increase the emission efficiency due to the greater rigidity and, in the meantime, allow strong interligand stacking that could deteriorate the emission efficiency. We bypassed this hurdle by design of five bis-tridentate Ir(III) complexes (1-5), to which both of their monoanionic ancillary and dianionic chromophoric chelate were functionalized derivative of 2-pyrazolyl-6-phenylpyridine, i.e. pzpyphH2 parent chelate. Hence, addition of phenyl substituent to the pyrazolyl fragment of pzpyphH2 gave rise to the precursors of monoanionic chelate (A1H-A3H), on which the additional tert-butyl and/or methoxy groups were introduced at the selected positions for tuning their steric and electronic properties, while precursors of dianionic chelates was judiciously prepared with an isoquniolinyl central unit on pziqphH2 in giving the red-shifted emission (cf. L1H2 and L2H2). Factors affected their photophysical properties were discussed by theoretical methods based on DFT and TD-DFT calculation, confirming that the T1 excited state of all investigated Ir(III) complexes shows a mixed metal-to-ligand charge transfer (MLCT), intraligand charge transfer (ILCT), ligand-to-ligand charge transfer (LLCT), and ligand-centered (LC) transition character. In contrast, the poor quantum yield of 3 is due to the facilitation of the nonradiative decay in comparison to the radiative process. As for potential OLED applications, Ir(III) complex 2 gives superior performance with max. efficiencies of 28.17%, 41.25 cd·A-1 and 37.03 lm·W-1, CIEx,y = 0.63, 0.37 at 50 mA cm-2, and small efficiency roll-off.
- Gnanasekaran, Premkumar,Yuan, Yi,Lee, Chun-Sing,Zhou, Xiuwen,Jen, Alex K.-Y.,Chi, Yun
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supporting information
p. 10944 - 10954
(2019/09/09)
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- A Silver-Catalyzed Modular Intermolecular Access to 6,6-Spiroketals
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A modular synthesis of 6,6-spiroketals via silver catalysis is reported. By combining an intermolecular Michael addition and a 6-endo-dig cyclization, this cascade reaction allows the modular preparation of highly substituted 6,6-spiroketals by combining two substrate molecules. Established methods accessing this interesting substructure are complemented by this new transformation. The protocol tolerates diverse substitution patterns and functional groups. (Figure presented.).
- Ahrens, Alexander,Heinrich, Niklas F.,Kohl, Simon R.,Hokamp, Martha,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 5605 - 5615
(2019/12/11)
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- Gold-Catalyzed Cyclisation by 1,4-Dioxidation
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Amide-substituted diynes were cyclized in the presence of a cationic gold catalyst and an external nucleophile leading to 1-indenones and 1-iminoindenones. The electron-donating features of the nitrogen atom enable the formation of a reactive ketene iminium ion, which can be trapped by either diphenyl sulfoxide or anthranil as nucleophiles in a subsequent oxidation step, providing substituted inden-1-on-3-carboxamides.
- Claus, Vanessa,Molinari, Lise,Büllmann, Simon,Thusek, Jean,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 9385 - 9389
(2019/04/30)
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- Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis
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The bis-ortho-thioether 9,10-bis[(o-methylthio)phenyl]anthracene was synthesized as a syn-atropisomer, as revealed by X-ray diffraction. This alkylaryl thioether ligand (L) formed different macrocyclic complexes by coordination with silver(I) salts depending on the nature of the anion: M2L2 for AgOTf and AgOTFA, M6L4 for AgNO3. A discrete M2L complex was obtained in the presence of bulky PPh3AgOTf. These silver(I) complexes adopted similar structures in solution and in the solid state. As each sulfur atom in the ligand is prochiral, macrocycles L2M2 were obtained as mixtures of diastereoisomers, depending on the configurations of the sulfur atoms coordinated to silver cations. The X-ray structures of the two L2·(AgOTf)2 stereoisomers highlighted their different geometry. The catalytic activity of all silver(I) complexes was effective under homogeneous conditions in two tandem addition/cycloisomerization of alkynes using 0.5-1 mol % of catalytic loading.
- Cao, Zhen,Lacoudre, Aline,Rossy, Cybille,Bibal, Brigitte
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supporting information
p. 2465 - 2472
(2019/11/11)
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- Development of a fused imidazo[1,2-: A] pyridine based fluorescent probe for Fe3+ and Hg2+ in aqueous media and HeLa cells
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A new fluorescent sensor 5 based on a fused imidazopyridine scaffold has been designed and synthesized via cascade cyclization. The reaction features the formation of three different C-N bonds in sequence. Imidazopyridine based fluorescent probe 5 exhibits highly sensitive and selective fluorescent sensing for Fe3+('turn-on') and Hg2+('turn-off'). The excellent selectivity of imidazopyridine for Fe3+/Hg2+ was not hampered in the presence of any of the competing cations. The limit of detection (LOD) of 5 toward Fe3+ and Hg2+ has been estimated to be 4.0 ppb and 1.0 ppb, respectively, with a good linear relationship (R2 = 0.99). Notably, 5 selectively detects Fe3+/Hg2+ through fluorescence enhancement signalling both in vitro and in HeLa cells.
- Srivastava, Suman,Thakur, Neha,Singh, Ashutosh,Shukla, Poonam,Maikhuri, Vipin Kumar,Garg, Neha,Prasad, Ashok,Pandey, Rampal
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p. 29856 - 29863
(2019/10/02)
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- A Mild and Regioselective Synthesis of α-Fluoroketones via Gold and Selectfluor Partnership
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An efficient, mild and rapid synthesis of α-fluoroketones has been developed, via a fruitful association between gold and Selectfluor starting from aldehyde-yne and alkynylaryl ketone derivatives. Several functionalized and synthetically highly valuable α-fluoroketones (21 compounds, up to 92%) were isolated in good to excellent yields via a remarkable regioselective oxyfluorination reaction in EtOH/H2O at room temperature. We have shed some light on parts of the mechanism by reacting diphenylacetylene and aldehyde-yne with or without Selectfluor. The reaction most presumably occurs via a sequential gold-catalyzed regioselective hydration followed by the α-fluorination reaction, but the presence of aldehyde moiety is crucial for the reactivity of alkyne function. The fluoroketones were efficiently transformed to 4-fluoroisoquinolines (9 compounds, 82–95%) of high pharmaceutical interest. (Figure presented.).
- Chen, Xi,Martini, Sophie,Michelet, Véronique
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p. 3612 - 3618
(2019/07/10)
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- A Metal-Free Route to Heterocyclic Trifluoromethyl- and Fluoroalkylselenolated Molecules
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A metal-free methodology to easily synthesize various CF3Se-containing heterocyclic compounds has been developed through intramolecular ring closures of alkynes promoted with CF3SeCl. Moreover, this strategy has also been extended to other fluoroalkylselenyl groups.
- Glenadel, Quentin,Ismalaj, Ermal,Billard, Thierry
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supporting information
p. 56 - 59
(2018/01/17)
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- Selective Divergent Synthesis of Indanols, Indanones, and Indenes via Acid-Mediated Cyclization of (Z)- and (E)-(2-Stilbenyl)methanols and Its Application for the Synthesis of Paucifloral F Derivatives
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Starting from bromo/iodobenzaldehyde derivatives, the corresponding (Z)- and (E)-(2-stilbenyl)methanols could be prepared in 2-5 steps via Pd-catalyzed cross-coupling reactions (Sonogashira and Heck reactions) followed by aryllithium/aryl Grignard addition. For the (E)-stilbenes, subsequent acid-mediated cyclization using p-TsOH immobilized on silica (PTS-Si) at low temperatures furnished the 2,3-trans-1-indanols with complete stereocontrol at the C2-C3. Further oxidization of the alcohol provided the indanones, which are structurally related to the natural product paucifloral F. At higher temperatures, 1,2- and 2,3-disubstituted indenes could be selectively prepared in good to excellent yields. On the other hand, the (Z)-stilbenes, under similar conditions (PTS-Si), did not give the indanols; only the 1,2-disubstituted indenes could be obtained. To gain further insights into the stereochemistry at C2-C3 for the (Z)-stilbenes, hydride or azide was employed as a nucleophile; the corresponding indane products were obtained with the cis stereochemistry at the C2-C3. Thus, the (Z)- or (E)-olefin geometry of the substrate directed the stereoselective indanyl cyclization to furnish the cis or trans at the C2-C3 ring junction, respectively, while reaction conditions controlled the selectivity of the product types.
- Jongcharoenkamol, Jira,Chuathong, Patsapon,Amako, Yuka,Kono, Masato,Poonswat, Kasam,Ruchirawat, Somsak,Ploypradith, Poonsakdi
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p. 13184 - 13210
(2018/11/02)
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- Magnetically retrievable N-heterocyclic carbene-silver complex with wingtip ferrocenyl group for Sonogashira coupling
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A new magnetically retrievable N-heterocyclic carbene-silver complex with wingtip ferrocenyl group has been prepared by multi-step procedure. The formation of complex was confirmed on the basis of analytical techniques such as FT-IR, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD), transmission electron microscopy (TEM) and VSM (vibrating sample magnetometer) analysis. The complex was successfully employed as an efficient heterogeneous catalyst for Sonogashira coupling reaction of aryl halides with terminal alkynes. The complex could be separated easily by applying external magnet. The reusability studies revealed that complex can be reused up to eight times without significant decrease in catalytic activity.
- Naikwade, Altafhusen,Bansode, Prakash,Rashinkar, Gajanan
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p. 112 - 122
(2018/05/03)
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- Heterocyclic Iodoniums for the Assembly of Oxygen-Bridged Polycyclic Heteroarenes with Water as the Oxygen Source
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A diverse set of novel heterocyclic iodoniums was synthesized for the first time. The reactions of these unique iodoniums with environmentally benign water as the oxygen source provided structurally complex oxygen-incorporated heteropolycycles that are essential motifs in natural products and biologically active compounds. The transformation only required low-cost copper acetate. Further derivatization of the obtained polycycles expanded the structural diversity, which is important in the building of chemical libraries for drug discovery.
- Zhu, Daqian,Wu, Zhouming,Luo, Bingling,Du, Yongliang,Liu, Panpan,Chen, Yunyun,Hu, Yumin,Huang, Peng,Wen, Shijun
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supporting information
p. 4815 - 4818
(2018/08/24)
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- Ferrocenyl bisoxazoline as an efficient non-phosphorus ligand for palladium-catalyzed copper-free Sonogashira reaction in aqueous solution
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Pd(OAc)2-catalyzed Sonogashira coupling reactions of alkynes and a variety of aryl halides with 1,3-bis(5-ferrocenylisoxazoline-3-yl)benzene as an efficient non-phosphorus ligand under copper-free conditions are presented. The main advantages over previous methodologies include low catalyst loading (0.2 mol% Pd(OAc)2 and 0.4 mol% ferrocenyl bisoxazoline ligand are sufficient for these coupling reactions), less problematic reaction medium (water–dimethylformamide) and more convenient operation (no requirement for nitrogen protection).
- Yu, Shuyan,Wu, Jingxin,He, Xinwei,Shang, Yongjia
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- Cyclic analogue of S-benzylisothiourea that suppresses kynurenine production without inhibiting indoleamine 2,3-dioxygenase activity
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Kynurenine is biosynthesised from tryptophan catalysed by indoleamine 2,3-dioxygenase (IDO). The abrogation of kynurenine production is considered a promising therapeutic target for immunological cancer treatment. In the course of our IDO inhibitor programme, formal cyclisation of the isothiourea moiety of the IDO inhibitor 1 afforded the 5-Cl-benzimidazole derivative 2b-6, which inhibited both recombinant human IDO (rhIDO) activity and cellular kynurenine production. Further derivatisation of 2b-6 provided the potent inhibitor of cellular kynurenine production 2i (IC50 = 0.34 μM), which unexpectedly exerted little effect on the enzymatic activity of rhIDO. Elucidation of the mechanism of action revealed that compound 2i suppresses IDO expression at the protein level by inhibiting STAT1 expression in IFN-γ-treated A431 cells. The kynurenine-production inhibitor 2i is expected to be a promising starting point for a novel approach to immunological cancer treatment.
- Fukuda, Miwa,Sasaki, Tomomi,Hashimoto, Tomoko,Miyachi, Hiroyuki,Waki, Minoru,Asai, Akira,Takikawa, Osamu,Ohno, Osamu,Matsuno, Kenji
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supporting information
p. 2846 - 2849
(2018/07/30)
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- Synthesis and photophysical properties of imine borane adducts towards vapochromic materials
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A series of alkynyl aryl conjugated aldehydes and imines were prepared and their adducts with various Lewis acidic boranes have been studied via NMR, absorption, and luminescence spectroscopies in solution. The imine-B(C6F5)3 adduct showed remarkable solution stability, and was then trialled in vapochromism experiments using simple impregnated paper strips to examine the fluorescence responses.
- Soltani, Yashar,Adams, Samuel J.,B?rger, Jennifer,Wilkins, Lewis C.,Newman, Paul D.,Pope, Simon J.A.,Melen, Rebecca L.
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supporting information
p. 12656 - 12660
(2018/09/27)
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- N-heterocyclic carbene-Pd(II) complex based on theophylline supported on Fe3O4@SiO2 nanoparticles: Highly active, durable and magnetically separable catalyst for green Suzuki-Miyaura and Sonogashira-Hagihara coupling reactions
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In this paper, a novel heterogeneous palladium catalyst was synthesized by anchoring N-heterocyclic carbene-Pd(II) complex based on theophylline on magnetic Fe3O4@SiO2 nanoparticles. The synthesized magnetic composite was characterized by fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), N2 adsorption-desorption isotherm analysis (BET), UV–vis spectroscopy and elemental analysis. Also, loading content of palladium on the catalyst was measured by inductive coupled plasma (ICP) analysis. The synthesized catalyst was used successfully for the Suzuki cross-coupling reactions of various aryl halides (I, Br, Cl) with phenylboronic acids. This reaction was best performed in water as a green solvent in the presence of just 0.37–0.5 mol% of the catalyst at 60 °C. Also, we have reported this recyclable catalytic system as a stable phosphine-free Pd catalyst for the Sonogashira cross-coupling of aryl halides (I, Br, Cl) with terminal aromatic and aliphatic alkynes under solvent-free conditions. All coupling reactions proceeded with good to excellent yields. The catalyst showed good stability and was recovered and reused for eight reaction cycles without a significant loss in its catalytic activity. Also, the leaching of the catalyst has been examined by a hot filtration test and ICP-AES analysis.
- Esmaeilpour, Mohsen,Sardarian, Ali Reza,Firouzabadi, Habib
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- Palladium nanoparticles immobilized on EDTA-modified Fe3O4@SiO2 nanospheres as an efficient and magnetically separable catalyst for Suzuki and Sonogashira cross-coupling reactions
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In this study, a novel heterogeneous palladium catalyst was synthesized by anchoring palladium onto ethylenediaminetetraacetic acid (EDTA)-coated Fe3O4@SiO2 magnetic nanocomposite and used for the Suzuki and Sonogashira cross-coupling reactions. The properties of the magnetic catalyst were characterized by FT-IR, XRD, TEM, FE-SEM, DLS EDX, XPS, N2 adsorption-desorption isotherm analysis, TGA, VSM, elemental analysis and the loading level of Pd in catalyst was measured to be 0.51?mmol/g by ICP. The catalyst was used in Suzuki cross-coupling reactions of various aryl halides, including less reactive chlorobenzenes with phenylboronic acid without any additive or ligand under green conditions. Furthermore, we have reported this recyclable catalytic system for Sonogashira cross-coupling reactions of various aryl halides (I, Br, Cl) under copper and ligand-free conditions in the presence of DMF/H2O (1:2/v:v) as a solvent. The magnetic catalyst could also be separated by an external magnet and reused six times without any significant loss of activity.
- Esmaeilpour, Mohsen,Zahmatkesh, Saeed,Fahimi, Nafiseh,Nosratabadi, Mehran
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- Hypervalent iodine compound containing heterocyclic ring as well as preparation method and application thereof
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The invention discloses a hypervalent iodine compound containing a heterocyclic ring as well as a preparation method and application thereof. A structure of the compound is shown as a formula (I): theformula (I) is shown in the description, wherein R is selected from hydrogen, halogen, alkyl, alkoxy, halogenated alkyl, halogenated alkoxy, nitryl, cyano, hydroxyl or -COOR'; R' is alkyl or halogenated alkyl; and Het is substituted or non-substituted 1,4-benzopyranone, substituted or non-substituted quinolone, substituted or non-substituted isoquinoline, substituted or non-substituted thiobenzopyranone, substituted or non-substituted coumarin and substituted or non-substituted oxepin. The compound disclosed by the invention is novel in structure and is the hypervalent iodine compound containing the heterocyclic ring; the hypervalent iodine compound is stable in structure and simple in preparation method; and meanwhile, the hypervalent iodine compound has a very good inhibition effect onML-1 and MOLM-13 cells and has an extremely great application prospect on prevention and/or treatment effect on leukemia.
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Paragraph 0151; 0152; 0153
(2019/01/08)
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- Construction of Six-Membered Silacyclic Skeletons via Platinum-Catalyzed Tandem Hydrosilylation/Cyclization with Dihydrosilanes
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Catalytic silicon-carbon or silicon-heteroatom bond-forming hydrosilylation has become increasingly important in synthetic chemistry, catalysis and organosilicon chemistry. Herein we report a platinum-catalyzed one-pot and tandem hydrosilylation/cyclization of OH-containing alkynes with dihydrosilanes, allowing for facile synthesis of six-membered organosilicon compounds, including silyloxycycles and cyclic siloxanes in high yields and with good stereoselectivities. (Figure presented.).
- Long, Peng-Wei,Bai, Xing-Feng,Ye, Fei,Li, Li,Xu, Zheng,Yang, Ke-Fang,Cui, Yu-Ming,Zheng, Zhan-Jiang,Xu, Li-Wen
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supporting information
p. 2825 - 2830
(2018/08/17)
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- Borane-catalyzed indole synthesis through intramolecular hydroamination
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The reaction of 2-alkynyl anilines with catalytic amounts of B(C6F5)3 (5 mol%) resulted in the formation of 2-substituted indoles according to an intramolecular hydroamination in good to excellent yields. Reaction intermediates as well as products were characterized by NMR spectroscopy and by X-ray crystallography. The domino hydroamination/hydrogenation sequence allowed the efficient synthesis of tetrahydroquinoline 8 in good yield.
- Tussing, Sebastian,Ohland, Miriam,Wicker, Garrit,Fl?rke, Ulrich,Paradies, Jan
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supporting information
p. 1539 - 1545
(2017/02/10)
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- Synthesis of selectively 4-substituted 9,9′-spirobifluorenes and modulation of their photophysical properties
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Synthesis of selectively 4-substituted 9,9′-spirobifluorenes was accomplished by using catalytic [2 + 2 + 2]-cyclotrimerization of specifically substituted diynols with alkynes to the corresponding fluorenols. Further synthetic transformations provided the target molecules. The measurement of the photophysical properties of the prepared 4-substituted 9,9′-spirobifluorenes revealed that their emission maxima depended on the electronic properties of the substituents present in the para position: the presence of an electron accepting group strongly favored the maxima red shift toward the blue VIS region (CF3λmax = 361 nm vs. MeO λmax = 330 nm). Adding further substituents (aryl or arylethynyl moieties) on the phenyl ring in position 4 did not lead to a dramatic improvement in the emission maxima (CF3C6H4, λmax = 369 nm, CF3C6H4CC, λmax = 370 nm), but increased their quantum yields considerably. In addition, a series of 9,9′-spirobifluorenes possessing various extended π-systems (pyrene, anthracene, etc.) were synthesized. In general, the emission maxima pattern reflected that of the parent π-systems, but they were red shifted by 10-30 nm. Finally, also a 1-[4-(9,9′-spirobifluorene-4-yl)phenyl]-2-aryl-ortho-carborane was prepared. These data thus may provide guidelines for further design of 9,9′-spirobifluorenes with tailored properties.
- Kaiser, Reinhard P.,Mosinger, Ji?í,Císa?ová, Ivana,Kotora, Martin
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supporting information
p. 6913 - 6920
(2017/09/01)
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- Sonogashira (Cu and amine free) and Suzuki coupling in air catalyzed: Via nanoparticles formed in situ from Pd(ii) complexes of chalcogenated Schiff bases of 1-naphthaldehyde and their reduced forms
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The reaction of 1-naphthaldehyde with 2-(phenylthio/seleno)ethylamine afforded air- and moisture-insensitive Schiff bases: C10H7-1-CHN-CH2CH2EPh (L1: E = S; L2: E = Se). Then, on treatment with NaOAc and Li2PdCl4, palladacycles, [Pd(L1-H/L2-H)Cl] (1/2) were formed at room temperature, in which L1/L2 are ligated as an unsymmetric (C-, N, E) pincer. The reduction of >CN bonds of L1 and L2 with sodium borohydride gave C10H7-1-CH2NH-CH2CH2EPh (L3: E = S; L4: E = Se). The reactions of L3/L4 at room temperature, similar to those of L1/L2, resulted in the formation of complex [Pd(L3/L4)Cl2] (3/4), in which the ligand is coordinated in a bidentate (N, E) mode. The yield of all the complexes was >85%. Characterization by HR-MS, 1H, 13C{1H} and 77Se{1H} NMR spectra of L1-L4 and their complexes 1-4 were performed. The structures of L1 and 1-4 were established with single-crystal X-ray diffraction. In all the complexes, the geometry of palladium was distorted square planar. The Pd-S bond distances in 1 and 3 were 2.426(12) and 2.259(2) ?, respectively, whereas Pd-Se bond lengths (?) were 2.523(11) (2) and 2.369(10) (4) ?. The catalytic activities of 1-4 were explored for copper- and amine-free Sonogashira and Suzuki-Miyaura coupling (SMC) of aryl halides under aerobic conditions. The amount of catalyst required for achieving good conversion was 0.01 and 0.05 mol% for SMC and Sonogashira coupling, respectively. The conversion of some substrates reached a maximum in 1 and 2 h for Sonogashira coupling and SMC, respectively. The palladacycles as catalysts gave good conversion efficiency. The generation of palladium-containing nanoparticles (NPs) during both coupling reactions was observed. These were isolated and HR-TEM studies were performed on them and revealed their size as ~2-7 nm. The SEM-EDX analysis indicated the presence of organochalcogen ligands or their fragments in the samples. They independently catalyzed both reactions. Therefore, the role of 1-4 in catalysis undoubtedly exists. For Sonogashira coupling, the formation and role of such Pd-based NPs under aerobic conditions were observed for the first time. The complexes 1-4 showed the potential for reuse, as in the eighth cycle, conversion dropped by only 20%.
- Bhaskar, Renu,Sharma, Alpesh K.,Yadav, Manoj K.,Singh, Ajai K.
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p. 15235 - 15248
(2017/11/22)
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- Palladium-Catalyzed Copper-Free Sonogashira Coupling of 2-Bromoarylcarbonyls: Synthesis of Isobenzofurans via One-Pot Reductive Cyclization
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Palladium-catalyzed copper-free Sonogashira coupling of 2-bromocarbonyls is presented. This method afforded the 2-alkynylaryl carbonyls, useful synthons for the accomplishment of many carbocyclic and heterocyclic motifs. Significantly, the strategy was extended to the one-pot synthesis of isobenzofurans via reduction followed by intramolecular 5- exo -dig cyclization.
- Krishna Reddy, Alavala Gopi,Satyanarayana, Gedu
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supporting information
p. 5149 - 5158
(2017/10/06)
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- Palladium stabilized on poly and mono sulfonamide ligands as novel, simple, effective, and recyclable nano catalysts for C-C cross-coupling reactions
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Poly and mono sulfonamide ligands were successfully used for the stabilization of palladium nanoparticles. The prepared nano catalysts that appeared to be heterogeneous and novel were characterized with various analytical tools. To establish the catalytic activity of the prepared catalysts, they were used in the Suzuki-Miyaura and Sonogashira-Hagihara coupling reactions of aryl halides under low palladium loading conditions. The catalysts showed good stability and could be recovered and reused for seven reaction cycles without significant loss of catalytic activity.
- Ghorbani-Vaghei, Ramin,Sarmast, Narges
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p. 1073 - 1080
(2017/10/03)
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- Highly selective construction of medium-sized lactams by palladium-catalyzed intramolecular hydroaminocarbonylation of aminoalkynes
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A novel palladium-catalyzed intramolecular hydroaminocarbonylation of aminoalkynes has been developed. This direct and operationally simple protocol provides a rapid and reliable approach to a diverse array of valuable seven-and eight-membered lactams with high chemoselectivity and regioselectivity. The high selectivity might be attributed to rational tuning the electronic nature of the amine moiety and the palladium catalyst which enabled this transformation to proceed in the absence of acidic or any other additives under fairly mild reaction conditions. This method paves the way for the synthesis of medium-sized lactams.
- Hu, Yue,Huang, Hanmin
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supporting information
p. 5070 - 5073
(2017/11/07)
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- Visible-Light-Promoted Generation of α-Ketoradicals from Vinyl-bromides and Molecular Oxygen: Synthesis of Indenones and Dihydroindeno[1,2-c]chromenes
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Ortho-alkynylated α-bromocinnamates can be converted by a visible-light-mediated photocascade reaction with molecular oxygen into either indenones or dihydroindeno[1,2-c]chromenes. The one-step process features key photochemical steps, that is, the initial activation of vinyl bromides through energy transfer to give α-ketoradicals in a reaction with molecular oxygen, followed by α-oxidation of an arene moiety by 6-π electrocyclization, and subsequent hydroxylation by an electron-transfer process from the same photocatalyst leads to the dihydroindeno[1,2-c]chromenes.
- Pagire, Santosh K.,Kreitmeier, Peter,Reiser, Oliver
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supporting information
p. 10928 - 10932
(2017/08/30)
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- A nickel(II) thiosemicarbazonato complex: synthesis, structure, electrochemistry, and application in catalytic coupling of terminal alkynes with arylboronic acids
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Abstract: A simple route for the synthesis of a new square-planar nickel(II) complex of 2-((3-methylthiophen-2-yl)methylene)hydrazinecarbothioamide is described. Elemental analysis, solution conductivity, and spectral measurements were used to authenticate the composition of the complex. In addition, the X-ray crystal structure of the complex was obtained. Each of the two ligands of the centrosymmetric structure is coordinated to the metal center via the azomethine N and the thioimidate S atoms, forming five-membered chelate rings. Infrared and NMR spectroscopic features of the complex are consistent with its molecular structure. The complex displays a quasi-reversible reduction with E1/2 of ?0.83?V (ΔEp 160?mV), indicating that the ligand system can stabilize the Ni(I) oxidation state. The complex acts as an active catalyst for the C–C coupling of aryl acetylenes with arylboronic acids containing a variety of substituents. The influence of solvent, base, reaction temperature, and catalyst loading on the C–C coupling reaction was evaluated. Graphical abstract: A new square-planar nickel(II) complex bearing 2-((3-methylthiophen-2-yl)methylene)-hydrazinecarbothioamide was synthesized and characterized by elemental analysis, FTIR, NMR, and single-crystal X-ray crystallographic technique. Cyclic voltammetric study indicates stabilization of Ni(I) oxidation state. The complex acts as an effective catalyst for the carbon–carbon cross-coupling reaction of substituted phenylacetylenes with various arylboronic acids under optimized conditions.[Figure not available: see fulltext.].
- Prabhu, Rupesh Narayana,Lakshmipraba, Jagadeesan
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p. 579 - 585
(2017/09/15)
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- ALKENES AS ALKYNE EQUIVALENTS IN RADICAL CASCADES TERMINATED BY FRAGMENTATIONS
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Disclosed are methods for rerouting radical cascade cyclizations by using alkenes as alkyne equivalents. The reaction sequence is initiated by a novel 1,2 stannyl shift which achieves chemo- and regioselectivity in the process. The radical “hopping” leads to the formation of the radical center necessary for the sequence of selective cyclizations and fragmentations to follow. In the last step of the cascade, the elimination of a rationally designed radical leaving group via β-C—C bond scission aromatizes the product without the need for external oxidant. The Bu3Sn moiety, which is installed during the reaction sequence, allows further functionalization of the product via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of enynes into extended polycyclic structures of tunable dimensions.
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Paragraph 0163; 0164
(2016/12/22)
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- Zinc-Catalyzed Tandem Diels–Alder Reactions of Enynals with Alkenes: Generation and Trapping of Cyclic o-Quinodimethanes (o-QDMs)
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A systematic investigation of ZnCl2-catalyzed reactions of enynals with alkenes has been undertaken. Structurally unique propeller-like products could be obtained under mild conditions. Cyclic o-quinodimethanes (o-QDMs) are generated through [4+2] cycloaddition between enynals and alkenes. Both electron-poor and electron-rich dienophiles could be used to trap the active intermediate through [4+2] cycloaddition. But [1,5]-H shift products could also be observed when electron-rich alkenes were used as dienophile. DFT calculations were performed to understand the reaction mechanism. A competition between the [4+2] cycloaddition and [1,5]-H shift was proposed for the transformation of cyclic o-QDMs. The selectivity could be affected by the properties of the substrates. (Figure presented.).
- Zhang, Jiantao,Xiao, Yelin,Chen, Kai,Wu, Wanqing,Jiang, Huanfeng,Zhu, Shifa
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supporting information
p. 2684 - 2691
(2016/09/03)
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- Domino Fragmentations in Traceless Directing Groups of Radical Cascades: Evidence for the Formation of Alkoxy Radicals via C-O Scission
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Direct evidence for the formation of alkoxy radicals is reported in radical cascades using traceless directing groups. Despite the possibility of hydrogen abstraction in the fragmenting step, followed by loss of R-OH, β-scission is preferred for the formation of alkoxy radicals. For the first time, the C-O radical was intermolecularly trapped using a silyl enol ether. Various C-X fragmenting groups were explored as possible traceless directing groups for the preparation of extended polyaromatics. Computational evidence shows that a combination of aromatization, steric and stereoelectronic effects assists the fragmentation to alkoxy radicals. Additionally, a new through-space interaction was discovered between O and Sn in the fragmentation as a specific transition state stabilizing effect.
- Harris, Trevor,Gomes, Gabriel Dos Passos,Clark, Ronald J.,Alabugin, Igor V.
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p. 6007 - 6017
(2016/07/26)
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- Dendrimer-encapsulated Pd(0) nanoparticles immobilized on nanosilica as a highly active and recyclable catalyst for the copper- and phosphine-free Sonogashira-Hagihara coupling reactions in water
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This study demonstrates a new synthetic strategy for the preparation of porous SiO2 for catalytic applications using natural and waste materials from rice husks as the source of biosilica. Biogenic porous silica nanoparticles with a mean diameter of 45 nm were successfully prepared from rice husk (RH) biomass via a new multistep method. During the first step, sodium silicate is extracted from rice husks. Then, cetyltrimethylammonium bromide (CTAB), HCl, and HOAc were added into sodium silicate solution, and the resulting mixture was sonicated. After the hydrothermal reaction, the collected samples were calcinated to obtain silica nanoparticles. Then, dendrimer-encapsulated Pd(0) nanoparticles supported on nano-silica with surface amino groups were fabricated. These materials are prepared by sequestering palladium ions within dendrimers followed by chemical reduction to yield the corresponding zero-valent palladium nanoparticles. The synthesized nanostructures were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS), N2 adsorption-desorption isotherm analysis, UV-vis spectroscopy and elemental analysis. The morphologies of the catalyst were characterized using a field emission scanning electron microscope (FE-SEM) and a transmission electron microscope (TEM). Also, its Pd content was determined by using an inductively coupled plasma (ICP) analyzer. This catalytic system was used as an efficient catalyst for Sonogashira reaction of aryl halides with alkynes under copper and phosphine ligand-free conditions in water. The catalyst was regenerated for five cycles of reaction without any significant loss in its activity. Also, the analysis of the reaction mixture by the ICP technique showed that the leaching of the catalyst was negligible.
- Esmaeilpour, Mohsen,Sardarian, Alireza,Javidi, Jaber
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p. 4005 - 4019
(2016/06/13)
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- Facile preparation of highly stable and active hybrid palladium nanoparticles: effectual, reusable and heterogeneous catalyst for coupling reactions
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Palladium nanoparticles were supported on a bed of Fe3O4@-NH2@Murexide using a simple and efficient method, and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission elec
- Adib, Mehdi,Yasaei, Zahra,Karimi-Nami, Rahman,Khakyzadeh, Vahid,Veisi, Hojat
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p. 748 - 752
(2016/09/04)
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- Combining Traceless Directing Groups with Hybridization Control of Radical Reactivity: From Skipped Enynes to Defect-Free Hexagonal Frameworks
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This work discloses the first general solution for converting oligoalkynes into polyaromatic polycyclic systems free of pentagonal defects. The efficiency and selectivity of this cascade originate from the combination of the Bu3Sn-mediated TDG
- Pati, Kamalkishore,dos Passos Gomes, Gabriel,Alabugin, Igor V.
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supporting information
p. 11633 - 11637
(2016/11/17)
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- TRACELESS DIRECTING GROUPS IN RADICAL CASCADES: FROM OLIGOALKYNES TO FUSED HELICENES WITHOUT TETHERED INITATORS
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The present disclosure is directed to a traceless directing group in a radical cascade. The chemo- and regioselectivity of the initial attack in skipped oligoalkynes is controlled by a propargyl alkoxy moiety. Radical translocations lead to the boomerang return of radical center to the site of initial attack where it assists to the elimination of the directing functionality via β-scission in the last step of the cascade. In some aspects, the reaction of the present invention is catalyzed by a stannane moiety, which allows further via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of skipped oligoalkynes into polycyclic ribbons of tunable dimensions.
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Paragraph 0207
(2016/06/13)
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