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1.
Cross-coupling reactions, such as Buchwald-Hartwig arylamination and direct intramolecular biaryl coupling by C–H activation, were carried out using various Palladium-N-heterocyclic carbenes (Pd–NHC) as catalysts. The yields were good to excellent. The latter strategy was adopted to transform two dibenzylbutane lignans, isolated from the leaves of Ocotea macrophylla (Lauraceae), into the corresponding dibenzocyclooctane lignans in good overall yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
2.
Pd/C‐Mediated Alkynylation of Indazoles: Synthesis and Pharmacological Evaluation of Mono and Dialkynyl‐Substituted Indazoles
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D. R. Gorja K. Shiva Kumar B. Dulla K. Mukkanti M. Pal 《Journal of heterocyclic chemistry》2014,51(2):374-382
The combination of Pd/C–CuI–PPh3 has been identified as an efficient catalytic system for the C–C bond formation between 6‐bromo‐3‐iodo‐1H‐indazole and terminal alkynes in ethanol. Mono and/or dialkynyl‐substituted indazoles can be prepared using this general and practical methodology in good to excellent yields. Some of the compounds synthesized were tested for cytotoxic activities in vitro. 相似文献
3.
Asymmetric Alkynylation/Lactamization Cascade: An Expeditious Entry to Enantiomerically Enriched Isoindolinones
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Dr. Vishnumaya Bisai Arun Suneja Prof. Dr. Vinod K. Singh 《Angewandte Chemie (International ed. in English)》2014,53(40):10737-10741
An unprecedented CuI–pybox‐diPh‐catalyzed highly enantioselective (up to >99 % ee) alkynylation/lactamization cascade has been developed as a general catalytic system for the synthesis of diversely substituted isoindolinones of immense biological importance. The cascade effects one C? C and two C? N bond‐forming events in one reaction vessel under operationally simple, additive‐free reaction conditions in good to excellent yields. The methodology was further extended to the synthesis of tetrahydroisoquinoline scaffolds common to several biologically active natural products in a two‐step sequence with remarkable selectivity (up to 94 % ee). 相似文献
4.
Mallappa Beerappa 《合成通讯》2018,48(2):146-154
N-methylmorpholine N-oxide and silver oxide (Ag2O) oxidized four component reaction for the preparation of pyranopyrazole with different substituted pattern have been developed which provides rapid access to a library of compounds in good to excellent yields by using benzyl halide, malanonitrile/ethyl cyanoacetate, diethylacetylenedicarboxylate/ethyl acetoacetate and hydrazine hydrate as reactants. This transformation involves the breaking of one C?O bond and formation of 2 C–C, 2 C–N, and a C?O bond leading to the formation of a five and six membered ring in one pot operation. 相似文献
5.
Carbohydrate Derivatives Bearing a gem-Dihalogenoethenyl Group Treated with the appropriate Wittig reagent, aldehydosugar derivatives ( 1–13 ) led in good to excellent yields to the expected gem-difluoro, gem-chlorofluoro-and/or gem-dichloroenoses ( 14–29 ). Examples of their dibromo analogues had been previously described (see e.g. [1]) but the diiodo derivatives could not be isolated, The influence of the conditions on the yields is reported as well as spectroscopic properties (particularly the long-range 13C, 19F- and 1H, 19F-coupling constants) of these new enoses. 相似文献
6.
Treatment of aliphatic nitro compounds with NaBH4 in alkaline ethanol in the presence of a catalytic amount of diaryl ditelluride at 25°C for 5–20 h produces the corresponding oximes, generally as a mixture of E/Z isomers, in fair to good yields. Arenetellurolate anion (ArTe−) generated in situ is suggested to be the active species for the reduction. 相似文献
7.
A new 3-trifluoromethyl-substituted triphenylamine-containing aromatic diacid monomer, N,N-bis(4-carboxyphenyl)-3-trifluoromethylaniline, was prepared by the substitution reaction of 3-trifluoromethylaniline with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. Novel aromatic polyamides with 3-trifluoromethyl-substituted triphenylamine moieties were prepared from the diacid and various aromatic diamines via the direct phosphorylation polycondensation. All the polyamides were amorphous and readily soluble in many polar organic solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone, and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability with relatively high glass-transition temperatures (258–327°C), 10% weight-loss temperatures above 500°C, and char yields higher than 60% at 800°C in nitrogen. These polymers had low dielectric constants of 3.22–3.70 (100 Hz), low moisture absorption in the range of 1.75–2.58%, and high transparency with an ultraviolet–visible absorption cut-off wavelength in the 375–395 nm range. Cyclic voltammograms of the polyamide films cast onto an indium tin oxide coated glass substrate exhibited a reversible oxidation redox couple with oxidation half-wave potentials (E1/2) of 0.95–1.00 V vs. Ag/AgCl in an acetonitrile solution. 相似文献
8.
Abdolreza Iraj Mansouri Zahra Hassani Mohammad Reza Islami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1753-1758
2-Aminobenzoic acids or 4-aminobenzoic acid react with dimethyl acetylenedicarboxylate/triphenylphosphine in less than 20 min at 15–25°C to produce new organic phosphorus compounds in good to excellent yields. The conversion occurs with selective N- over O-alkylation of the amino group and isolation of the products is accomplished simply by filtration. 相似文献
9.
Tunable Cascade Reactions of Alkynols with Alkynes under Combined Sc(OTf)3 and Rhodium Catalysis
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Dr. Deng Yuan Li Hao Jie Chen Prof. Dr. Pei Nian Liu 《Angewandte Chemie (International ed. in English)》2016,55(1):373-377
Two tunable cascade reactions of alkynols and alkynes have been developed by combining Sc(OTf)3 and rhodium catalysis. In the absence of H2O, an endo‐cycloisomerization/C? H activation cascade reaction provided 2,3‐dihydronaphtho[1,2‐b]furans in good to high yields. In the presence of H2O, the product of alkynol hydration underwent an addition/C? H activation cascade reaction with an alkyne, which led to the formation of 4,5‐dihydro‐3H‐spiro[furan‐2,1′‐isochromene] derivatives in good yields under mild reaction conditions. Mechanistic studies of the cascade reactions indicated that the rate‐determining step involves C? H bond cleavage and that the hydration of the alkynol plays a key role in switching between the two reaction pathways. 相似文献
10.
Juzo Nakayama Kenta Takahashi Yutaka Ono Michiyo Morita Yoshiaki Sugihara Akihiko Ishii 《Heteroatom Chemistry》2002,13(5):424-430
Acetylenes that possess two bulky alkyl substituents reacted with sulfur dichloride to furnish the corresponding 2,3‐dialkyl‐2,3‐dichlorothiiranes ( 5 ) nearly quantitatively. The alkaline hydrolysis of 5 afforded 2,3‐dialkylthiirene 1‐oxides ( 10 ) in high yields. These two reactions could be successively carried out in one flask, and 2,3‐di‐tert‐butyl‐, 2,3‐di‐(1‐adamantyl)‐, and 2‐(1‐adamantyl)‐3‐tert‐butylthiirene 1‐oxides ( 10a–c ) were obtained in 70, 80, and 90% yields, respectively, based on the starting acetylenes, thus providing the most convenient synthesis of thiirene 1‐oxides. Disulfur dichloride also reacted with acetylenes to give 5 in good yields with the elimination of one sulfur atom. Although the alkaline hydrolysis of 5 provided 10 exclusively, acid hydrolysis gave a mixture of α‐oxothioketone 9 and thiirene 1‐oxide 10 in modest yields. All thiirene 1‐oxides 10a–c isomerized to produce α‐oxothioketones 9 in high yields when heated in boiling toluene. Reactions of a bis‐acetylene ( 18 ) with disulfur dichloride and with sulfur dichloride gave a dihydropentathiepin ( 19 ) in high yields. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:424–430, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10070 相似文献
11.
Treatment of various electron‐deficient alkenes in DMSO with stable, dry, equimolar mixtures of either Me3S(O)I/KOt‐Bu or Me3S(O)I/NaH cleanly afforded the corresponding substituted cyclopropanes in good yields and short reaction times (<20 min for reactions at 50–60°C using 0.4–4.0 mmol alkene). 相似文献
12.
Diversity‐Oriented Synthesis of Substituted Benzo[b]thiophenes and Their Hetero‐Fused Analogues through Palladium‐Catalyzed Oxidative CH Functionalization/Intramolecular Arylthiolation
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Anand Acharya S. Vijay Kumar Prof. Hiriyakkanavar Ila 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):17116-17125
An efficient, high yielding route to multisubstituted benzo[b]thiophenes has been developed through palladium‐catalyzed intramolecular oxidative C?H functionalization–arylthiolation of enethiolate salts of α‐aryl‐β‐(het)aryl/alkyl‐β‐mercaptoacrylonitriles/acrylates or acrylophenones. The overall strategy involves a one‐pot, two‐step process in which enethiolate salts [generated in situ through base‐mediated condensation of substituted arylacetonitriles, deoxybenzoins, or arylacetates with (het)aryl (or alkyl) dithioates] are subjected to intramolecular C?H functionalization–arylthiolation under the influence of a palladium acetate (or palladium chloride)/cupric acetate catalytic system and tetrabutylammonium bromide as additive in N,N‐dimethylformamide (DMF) as solvent. In a few cases, the yields of benzo[b]thiophenes were better in a two‐step process by employing the corresponding enethiols as substrates. In a few examples, Pd(OAc)2 (or PdCl2) catalyst in the presence of oxygen was found to be more efficient than cupric acetate as reoxidant, furnishing benzothiophenes in improved yields by avoiding formation of side products. The method is compatible with a diverse range of substituents on the aryl ring as well as on the 2‐ and 3‐positions of the benzothiophene scaffold. The protocol could also be extended to the synthesis of a raloxifene precursor and a tubulin polymerization inhibitor in good yields. The versatility of this newly developed method was further demonstrated by elaborating it for the synthesis of substituted thieno‐fused heterocycles such as thieno[2,3‐b]thiophenes, thieno[2,3‐b]indoles, thieno[3,2‐c]pyrazole, and thieno[2,3‐b]pyridines in high yields. A probable mechanism involving intramolecular electrophilic arylthiolation via either a Pd‐S adduct or palladacycle intermediate has been proposed on the basis of experimental studies. 相似文献
13.
《Green Chemistry Letters and Reviews》2013,6(2):203-209
Abstract Commercially available lithium hydroxide monohydrate (LiOH·H2O) was found to be a novel “dual activation” catalyst for Knoevenagel condensation between malononitrile (1) or 3-methyl 1-phenyl-1H-pyrazol-5-(4H)-one (6) with aromatic aldehydes 2a–e leading to an efficient and easy synthesis of arylidenemalononitriles 3a–d and 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) 7a–c in short times. The reaction of aryl aldehydes with malononitrile afforded excellent yields after 1–6 min in aqueous media at room temperature. In case of 3-methyl-1-phenyl-1H-pyrazol-5-(4H)-one (6) and aromatic aldehydes afforded good yields after 60–75 min at 90°C. 相似文献
14.
Hung‐ju Yen Shiue‐ming Guo Jui‐ming Yeh Guey‐Sheng Liou 《Journal of polymer science. Part A, Polymer chemistry》2011,49(16):3637-3646
Two series of polyimides I – II with methyl‐substituted triphenylamine units were prepared from the diamines, 4,4′‐diamino‐2″,4″,6″‐trimethyltriphenylamine (Me3TPA‐diamine; 1 ) and 4,4′‐diamino‐4″‐methyltriphenylamine (MeTPA‐diamine; 2 ), and two commercially available tetracarboxylic dianhydrides via a conventional two‐step chemical imidization. All the polymers were readily soluble in many polar solvents and showed useful levels of thermal stability associated with high glass transition temperatures (266–340 °C) and high char yields (higher than 49% at 800 °C in nitrogen). The polymer films showed reversible electrochemistry/electrochromism accompanied by a color change from neutral pale yellow to green oxidized form with good coloration efficiency, switching time, and stability. The CO2 permeability coefficients (PCO2) and permeability selectivity (PCO2/PCH4) for these polyimide membranes were in the range of 34.1–229.2 barrer and 21.3–28.9, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
15.
C. R. Shahini Gautam Achar Srinivasa Budagumpi Ramesh B. Dateer Helge Müller-Bunz Matthias Tacke 《Journal of Coordination Chemistry》2019,72(3):528-549
A series of 1,3,4-trisubstituted-1,2,3-triazolium iodide salts (4a–c) were synthesized via a three-step reaction sequence. Corresponding anilines (1a–c) were converted to azides (2a–c) which were then treated with phenylacetylene with “Click” chemistry to access 1,4-disubstituted-1,2,3-triazoles (3a–c). Subsequent methylation of 1,4-disubstituted-1,2,3-triazoles (3a–c) yielded 1,3,4-trisubstituted-1,2,3-triazoliumiodide salts (4a–c) in appreciable yields. All the synthesized compounds were characterized by 1H and 13C NMR, ATR–IR spectroscopic techniques and elemental analyses. Additionally, the structure of 1-(4-chlorophenyl)-4-phenyl-1,2,3-triazole (3b) was confirmed by single crystal X-ray diffraction analysis. The catalytic activity of 4a–c in a catalytic system consisting of 1,3,4-trisubstituted-1,2,3-triazoliumiodide salt/palladium(II) acetate/base were investigated toward Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions. The Suzuki–Miyaura cross-coupling reactions were carried out under mild reaction conditions with good to excellent yields, whereas Heck–Mizoroki cross-coupling reactions were performed at elevated temperature with moderate yields. Further, in situ method skips the synthetic procedure of preparing the palladium(II) complexes and hence is more economical and less tedious. 相似文献
16.
L. Kotis M. Menyhard A. Sulyok G. Sáfrán A. Zalar J. Kovač P. Panjan 《Surface and interface analysis : SIA》2009,41(10):799-803
The relative sputtering yield of carbon with respect to tantalum was determined for 1 keV Ar+ ion bombardment in the angular range of 70°–82° (measured from surface normal) by means of Auger electron spectroscopy depth profiling of C/Ta and Ta/C bilayers. The ion bombardment‐induced interface broadening was strongly different for the C/Ta and Ta/C, whereas the C/Ta interface was found to be rather sharp, the Ta/C interface was unusually broad. Still the relative sputtering yields (YC/YTa) derived from the Auger electron spectroscopy depth profiles of the two specimens agreed well. The relative sputtering yields obtained were different from those determined earlier on thick layers, calculated by simulation of SRIM2006 and by the fitting equation of Eckstein. The difference increases with increase of angle of incidence. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
Chun Shan Wang Ching Hsuan Lin 《Journal of polymer science. Part A, Polymer chemistry》1999,37(7):891-899
A series of polyester‐amides that contain phosphorus were synthesized by low temperature solution condensation of 1,4‐bis(3‐aminobenzoyloxy)‐2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl) phenylene (III) with various aromatic acid chlorides in N‐methyl pyrrolidone (NMP). All polyester‐amides are amorphous and readily soluble in many organic solvents such as dimethylacetamide (DMAc), NMP, dimethylsulfoxide, and dimethylformamide at room temperature or on heating. Light yellow and flexible films of these polyester‐amides could be cast from the DMAc solutions. The polymers with an inherent viscosity of 0.26–0.72 dL/g were obtained in quantitative yields. These polyester‐amides have good mechanical properties (G′ of ∼ 109 Pa up to 200°C) and good thermal and flame retardant properties. The glass transition temperatures of these polyester‐amides ranged from 250 to 273°C. The degradation temperatures (Td 5%) in nitrogen ranged from 466 to 478°C and the char yields at 800°C were 59.6–65.2%. The limiting oxygen indexes of these polyester‐amides ranged from 35 to 43. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 891–899, 1999 相似文献
18.
The chiral N-(2-benzoylethyl)-N-tosylglycine esters 5a–h and the α-amino-γ-keto ester 6 were prepared from γ-(tosylamino) alcohols 7a–h . Irradiation of compounds 5a–c, e gave cis-3-hydroxyproline esters 20–23 (Scheme 6), partly with complete asymmetric induction by the C(1′)-substituent, whereas 6 gave enantiomerically pure 4-hydroxy-4-phenyl-L -proline esters 24 in good yield but low de (Scheme 6). The de of the photocyclization depended on the nature and/or size of the C(1′)-substituents. Irradiation of ketones 5d and 5f , bearing H-atoms at C(γ) with respect to the keto function, gave cyclobutanols (Scheme 9) in low yields besides the preferred Norrish-type-II cleavage product. Cyclopentanol 25 was a by-product of the photocyclization of 5c as a result of H? C(δ) abstraction from the t-Bu group. The structure of products 20, 22 , and 24a, b was established by NMR or X-ray analyses. 相似文献
19.
Assoman Kouakou Najat Abbassi Hakima Chicha Lahcen El Ammari Mohamed Saadi El Mostapha Rakib 《Heteroatom Chemistry》2015,26(5):374-381
New four‐substituted indazoles 4a–e were synthesized by regioselective nucleophilic substitution of hydrogen of N‐alkyl‐7‐nitroindazoles 2a,b with arylacetonitriles 3a–c . Compounds 4a–e were reacted with arylsulfonyl chloride in pyridine to give some new indazole linked sulfonamides with good yields. The SNH at position C‐4 of 7‐nitroindazole with arylacetonitrile is confirmed by X‐ray diffraction analysis of compounds 4e and 6a . 相似文献
20.
Bismuth chloride was used to catalyze the [2 + 3] cycloaddition between sodium azide with aryl nitriles, aliphatic nitriles, and vinyl nitriles. A number of 5-substituted 1H-tetrazoles were synthesized in water or isopropanol/water mixtures using microwave heating. Good yields were obtained for these reactions when heated for 1 h at 120–160 °C in a 3:1 isopropanol/water mixture. A few of the less reactive nitriles required longer reaction times for good yields. 相似文献