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  • Chemical-epigenetic method to enhance the chemodiversity of the marine algicolous fungus, Aspergillus terreus OUCMDZ-2739
    Tetrahedron (IF 2.651) Pub Date : 2017-11-20
    Kunlai Sun, Guoliang Zhu, Jiejie Hao, Yi Wang, Weiming Zhu

    Four new meroterpenoids identified as (4S)-4-decarboxylflavipesolide C (1), 1-(2,2-dimethylchroman-6-yl)-3-(4-hydroxyphenyl)propan-2-one (2), (R,E)-3-(2,2-dimethyl chroman-6-yl)-4-hydroxy-5-((2-(2-hydroxypropan-2-yl)-2,3-dihydrobenzofuran-5-yl)methylene) furan-2(5H)-one (3), methyl (R)-2-(2-(2-hydroxypropan-2-yl)-2,3-dihydrobenzofuran-5-yl) acetate (4), along with nine known compounds (5–13) were isolated from a chemical-epigenetic culture of Aspergillus terreus OUCMDZ-2739 with 10 μM trichostatin A (TSA). Under the same condition without TSA, A. terreus OUCMDZ-2739 produced different compounds (14–20), supporting that the chemical-epigenetic modification of fungi could enrich the chemodiversity of the fungal products. The cytotoxicity was observed for compound 8 against K562 cell, 9 against MCF-7 and K562 cells and 12 against MCF-7 cell with IC50 values of 9.5, 10.1, 13.0 and 8.5 μM, respectively. Compounds 3, 8 and 17 exhibited stronger α-glucosidase inhibition than 1-deoxynojirimycin and acarbose (positive controls) with IC50 values of 24.8, 1.2, 61.6, 191.7 and 555.1 μM, respectively. The enzyme kinetics study further indicated that compound 8 was an anticompetitive inhibitor with Ki value of 1.42 μM.

    更新日期:2017-11-20
  • Evidence for involvement of cationic intermediate in epoxidation of chiral allylic alcohols and unfunctionalised alkenes catalysed by MnIII(quinazolinone) complexes
    Tetrahedron (IF 2.651) Pub Date : 2017-11-20
    Murat Çakıcı, Hamdullah Kılıç, Sabri Ulukanlı, Duygu Ekinci

    A pair of MnIII(quinazolinone) complexes was prepared and evaluated in the catalytic epoxidation of the chiral allylic alcohols and unfunctionalised alkenes with iodosylbenzene. Epoxidation of chiral allylic alcohols with 1,3-allylic strain proceeded chemo- and diastereoselectively to give threo-epoxy alcohol (up to 99% d.r). Epoxidation of unfunctionalised alkenes by the proposed catalyst system proceeded nonselectively, as evidenced by the formation of isomerization and rearrangement products in the epoxidation of (Z)-stilbene. A three-step pathway involving a cationic intermediate is proposed for the formation of isomerization and rearrangement products. The fact that only products resulting from the cationic intermediate were detected in the oxidation of a mechanistic probe, (2-methoxy-3-vinylcyclopropyl)benzene, with MnIII(quinazolinone) and PhIO substantiated the cationic oxygen transfer mechanism.

    更新日期:2017-11-20
  • Synthesis of 2,4,6,8,9,11-hexaaza[3.3.3]propellanes as a new molecular skeleton for explosives
    Tetrahedron (IF 2.651) Pub Date : 2017-11-20
    Byeongil Lee, Moonyong Shin, Youngran Seo, Myeong Hak Kim, Hye Ryoung Lee, Jin Seok Kim, Kyu-hyun Chung, Dongwon Yoo, Young Gyu Kim

    Azapropellanes are of great interest in many disciplines, including materials science and medicinal chemistry. Various synthetic approaches for azapropellanes have been explored; however, the synthetic study of the polyazapropellane skeleton containing five or more nitrogen atoms is rare. Here, we report a simple yet highly efficient protocol for the synthesis of the hexaaza[3.3.3]propellane skeleton as a building block for high energy materials for the first time. The key reactions include the Boc2O-assisted cyclization of glycoluril diamine without a column purification step and the first full reduction of all the three carbonyl groups to the methylene groups through a combination of LiAlH4 and DIBAL-H. All the structures were confirmed by spectroscopic and X-ray analyses.

    更新日期:2017-11-20
  • Modification of Kagan's amide for improved activity as Chiral Solvating Agent in enantiodiscrimination during NMR analysis
    Tetrahedron (IF 2.651) Pub Date : 2017-11-20
    Nilesh Jain, Aditya N. Khanvilkar, Sibaprasad Sahoo, Ashutosh V. Bedekar

    A modification is proposed in Kagan's amide in order to improve its ability to offer stronger hydrogen bonding and hence better ability to bind with substrates. Introduction of chlorine in the amide aromatic ring along with the two nitro groups, increases the acidic character of amide hydrogen and makes the hydrogen bond stronger, the concept is tested by making three derivatives of Kagan's amide and the effect is confirmed by nmr analysis. The modified chlorinated Kagan's amides were then tested as chiral solvating agents for detection of optical purity of several types of substrates where the supramolecular recognition is measured by in situ nmr analysis. Several guest molecules such as amide, sulfoxide, epoxy-keto, hydroxy acid, diacid and phosphoric acid were scanned for this study and its efficiency is further established by comparison with samples of known optical purity.

    更新日期:2017-11-20
  • Assessment of the regioselectivity in the condensation reaction of unsymmetrical o-phthaldialdehydes with alanine
    Tetrahedron (IF 2.651) Pub Date : 2017-11-16
    Agathe C.A. D'Hollander, Nicholas J. Westwood

    One approach for the synthesis of isoindolinones, a privileged bioactive heterocyclic core structure, involves a condensation reaction of o-phthaldialdehydes with a suitable nitrogen-containing nucleophile. This fascinating reaction is revisited here in the context of the use of o-phthaldialdehydes that contain additional substituents in the aromatic ring leading to a detailed analysis of the regioselectivity of the reaction. Eleven monosubstituted o-phthaldialdehydes were synthesised and reacted with alanine. The regioselectivity observed across the eleven substrates led to the design of a disubstituted substrate that reacted with very high control. A gram-scale reaction followed by esterification gave one major regioisomer in high yield. In addition, the regioselectivity observed on reaction of two novel monodeuterated substrates led to an increased mechanistic understanding.

    更新日期:2017-11-20
  • First synthetic approach towards K-259-2, a unique calmodulin antagonist
    Tetrahedron (IF 2.651) Pub Date : 2017-11-16
    Shyam Basak, Smita Mandal, Dipakranjan Mal

    K-259-2, a unique calmodulin antagonist, is an allyl chain containing anthraquinone natural product. A regiospecific synthetic approach towards K-259-2 is herein represented. The study also showcases a protocol for synthesizing heavily substituted bromo naphthoate which was found to be suitable for fabricating the K-259-2 motif.

    更新日期:2017-11-20
  • Solvent-free, catalyst-free aza-Michael addition of cyclohexylamine to diethyl maleate: Reaction mechanism and kinetics
    Tetrahedron (IF 2.651) Pub Date : 2017-11-16
    Michal Bláha, Olga Trhlíková, Jiří Podešva, Sabina Abbrent, Miloš Steinhart, Jiří Dybal, Miroslava Dušková-Smrčková

    The aza-Michael reaction is the addition of an amine to an electron deficient C=C double bond. This reaction is also used in the synthesis of precursors of polymeric networks. In this study, we paid attention to the kinetics and mechanism of the aza-Michael addition of cyclohexylamine (CHXA) to diethyl maleate (DEM) performed as a solvent-free, catalyst-free reaction and to concurrent reactions. In situ Raman spectroscopy, NMR spectroscopy and gas chromatography/mass spectrometry have shown the occurrence of three simultaneous reactions: (i) the aza-Michael addition of CHXA to DEM leading to diethyl 2-(cyclohexylamino)succinate, (ii) isomerization of DEM to diethyl fumarate (DEF), and (iii) the aza-Michael addition of CHXA to DEF formed by the reaction (ii). All of these reactions proceed with third order kinetics, first order in DEM or DEF and second order in CHXA. We propose a kinetic model that allows kinetic constants to be estimated. Furthermore, a numerical solution of the set of differential equations confirms the expected kinetic equations of reactions (i) and (ii) and gives values of rate constants comparable to the estimated ones. A DFT mechanistic study illustrates the structure of the reaction intermediates and transition states of all reactions and explains the contribution of the second amine molecule in the reaction mechanism.

    更新日期:2017-11-20
  • Prenylated indole alkaloids and chromone derivatives from the fungus Penicillium sp. SCSIO041218
    Tetrahedron (IF 2.651) Pub Date : 2017-11-16
    Bin Yang, Huaming Tao, Xiuping Lin, Junfeng Wang, Shengrong Liao, Junde Dong, Xuefeng Zhou, Yonghong Liu

    Four new prenylated indole alkaloids (1–4), and four new chromone derivatives (7–10), together with six known compounds (5, 6, and 11–14), have been isolated from the mangrove sediment derived fungus Penicillium sp. SCSIO041218, cultured in the 1% NaCl PDB substrate. The structures of new compounds were determined by analysis of the NMR and MS spectroscopic data. The absolute configuration of the prenylated indole alkaloids were elucidated based on the comparison of ECDs with known analogues. The absolute configurations of the chromone derivatives were determined by time-dependent density functional theory calculations of the ECD spectra. In all of these isolated compounds, penixanthones A and B (12 and 13) exhibited antiallergic activities in vitro.

    更新日期:2017-11-20
  • Enantioselective approach to indolizidine and quinolizidine scaffolds. Application to the synthesis of peptide mimics
    Tetrahedron (IF 2.651) Pub Date : 2017-11-16
    Yuanyuan Lu, Sílvia Alujas-Burgos, Cristina Oliveras-González, Laura Vázquez-Jiménez, Pep Rojo, Ángel Álvarez-Larena, Pau Bayón, Marta Figueredo

    An enantioselective approach to substituted indolizidine and quinolizidine frameworks has been developed. Key steps of the synthesis are the enantioselective, palladium-catalyzed N-allylation of an imide, the nucleophilic allylation of an acyliminium ion and a ring closing metathesis. This general strategy has been applied to the synthesis of indolizidine peptide mimics, starting from a chiral imide derived from L-aspartic acid. It was observed that the preexisting stereogenic center of this substrate has a moderate influence on the stereoselectivity of the electrophilic allylation, which is mainly determined by the sense of chirality of the catalyst.

    更新日期:2017-11-20
  • A new enantioselective synthesis of the four stereoisomers of pallantione, the male-produced sex pheromone of Pallantia macunaima (Heteroptera: Pentatomidae) ☆
    Tetrahedron (IF 2.651) Pub Date : 2017-11-16
    Rafael Augusto Soldi, Daiane Szczerbowski, Paulo Henrique Gorgatti Zarbin

    In a previous study we reported the identification of the first ketone found in the Pentatomidae family, the sex attractant pheromone of the male stink bug Pallantia macunaima, (6R,10S)-6,10,13-trimethyltetradecan-2-one. Here we describe an efficient enantioselective route for the synthesis of the four stereoisomers of this pheromone. The synthesis was conceived as the connection of two chiral building blocks, employing (R)- or (S)-citronellol and methyl (S)-3-hydroxy-2-methylpropionate as the source of chirality.

    更新日期:2017-11-20
  • The potential of achiral sponge-derived and synthetic bromoindoles as selective cytotoxins against PANC-1 tumor cells
    Tetrahedron (IF 2.651) Pub Date : 2017-11-14
    Nicholas Lorig-Roach, Frances Hamkins-Indik, Tyler A. Johnson, Karen Tenney, Frederick A. Valeriote, Phillip Crews

    Our quest to isolate and characterize natural products with in vitro solid tumor selectivity is driven by access to repositories of Indo-Pacific sponge extracts. In this project an extract of a species of Haplosclerida sponge obtained from the US NCI Natural Products Repository displayed, by in vitro disk diffusion assay (DDA) and IC50 determinations, selective cytotoxicity with modest potency to a human pancreatic cancer cell line (PANC-1) relative to the human lymphoblast leukemia cell line (CCRF-CEM). Two brominated indoles, the known 6-bromo conicamin (1) and the new derivative, 6-Br-8-keto-conicamin A (2), were identified and 2 (IC50 1.5 μM for the natural product vs 4.1 μM for the synthetic material) was determined to be responsible for the cytotoxic activity of the extract against the PANC-1 tumor cell line. The new natural product and ten additional analogs were prepared for further SAR testing.

    更新日期:2017-11-15
  • N,N-dimethyl-D-glucosamine as an efficient ligand for copper-catalyzed Ullmann-type coupling of N-H heterocycles with aryl halides
    Tetrahedron (IF 2.651) Pub Date : 2017-11-14
    Jiao Jiao Wei, Wei Bin Song, Ye Fu Zhu, Bo Le Wei, Li Jiang Xuan

    A new N,N-dimethyl-d-glucosamine ligand has been developed for the copper-catalyzed Ullmann-type coupling of N-H heterocycles (e.g., indoles, benzimidazoles, pyrazoles and triazoles) with aryl halides. This method was accomplished not only featuring excellent yields, mild reaction conditions and simple operation, but also showing eco-friendly and broad-spectrum substrates, and could be widely used in the construction of N-aryl heterocyclic systems.

    更新日期:2017-11-15
  • Novel methodology for the synthesis of the benz[a]anthracene skeleton of the angucyclines using a Suzuki-Miyaura/isomerization/ring closing metathesis strategy
    Tetrahedron (IF 2.651) Pub Date : 2017-11-14
    Myron M. Johnson, Kennedy J. Ngwira, Amanda L. Rousseau, Andreas Lemmerer, Charles B. de Koning

    The synthesis of the benz[a]anthracene skeleton of the angucyclines is described. Key steps involve the Suzuki-Miyaura reaction, isomerization of an aromatic allyl substituent to the corresponding styrene, and the use of the ring closing metathesis reaction to construct a benzene ring. For example, exposure of 3-allyl-2-bromo-1,4,5-trimethoxynaphthalene to (2-formyl-4-methoxyphenyl)boronic acid under palladium catalysis conditions resulted in the formation of 2-(3-allyl-1,4,5-trimethoxynaphthalen-2-yl)-5-methoxybenzaldehyde. This 2-naphthyl benzaldehyde then underwent a Wittig reaction to furnish 3-allyl-1,4,5-trimethoxy-2-(4-methoxy-2-vinylphenyl)naphthalene. Isomerization of the allyl group of this compound afforded the diene, (E)-1,4,5-trimethoxy-2-(4-methoxy-2-vinylphenyl)-3-(prop-1-en-1yl)naphthalene. Exposure of the formed diene to the Grubbs II catalyst resulted in the formation of the benzanthracene, 3,7,8,12-tetramethoxytetraphene, which was easily oxidized to the corresponding quinone.

    更新日期:2017-11-15
  • One-pot synthesis of novel 3,10-dihydro-2H-1,3-oxazepino[7,6-b]indoles via 1,4-dipolar cycloaddition reaction
    Tetrahedron (IF 2.651) Pub Date : 2017-11-14
    Mervat S. Sammor, Ahmad Q. Hussein, Firas F. Awwadi, Mustafa M. El-Abadelah

    3,10-Dihydro-2H-1,3-oxazepino[7,6-b]indoles are synthesized via a convenient one-pot three-component 1,4-dipolar cycloaddition reaction, involving 3-alkyl(aryl)imidazo[1,5-a]pyridines, dimethyl acetylenedicarboxylate (DMAD) and N-alkylisatins. Structures of the newly synthesized heterocycles are evidenced from spectral data and further confirmed by single crystal X-ray diffraction. A plausible reaction mechanism is advanced, whereby the intermediate 1,4-dipole, generated in situ from imidazo[1,5-a]pyridine and DMAD, initially adds to the keto group of N-alkylisatins to form the corresponding 1,3-oxazin-spiro-oxindole cycloadduct. The latter undergoes subsequent unprecedented skeletal rearrangement through a cascade of bond breaking and bond making processes, eventually leading to ring enlargement, furnishing the tricyclic oxazepino[7,6-b]indole ring system as the end product.

    更新日期:2017-11-15
  • Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions
    Tetrahedron (IF 2.651) Pub Date : 2017-11-13
    Yongke Hu, Bindong Li

    A highly efficient palladium-catalyzed approach for the direct oxidative esterification of benzylic alcohols with methanol and long-chain aliphatic alcohols under mild conditions has been achieved. This practical catalyst system exhibits a broad substrate scope and good functional group tolerance. Catalytic amount of Bi(OTf)3 is used as co-catalyst to improve the activity and selectivity of the reactions. A variety of esters are obtained in yields of 43–96%.

    更新日期:2017-11-14
  • Mechanochemical synthesis of N-tert-butanesulfinyl imines under metal-free conditions
    Tetrahedron (IF 2.651) Pub Date : 2017-11-13
    Mohamed Elsherbini, Thomas Wirth

    A simple and convenient mechanochemical method for the condensation of aldehydes with tert-butanesulfinamide using catalytic amounts of iodine under metal- and solvent-free conditions is described.

    更新日期:2017-11-14
  • Photoinduced electron transfer-promoted debenzylation of phenylalanine and tyrosine derivatives using dicyanoarene
    Tetrahedron (IF 2.651) Pub Date : 2017-11-13
    Mugen Yamawaki, Yoshiki Okita, Takashi Yamamoto, Toshio Morita, Yasuharu Yoshimi

    Photoinduced debenzylations of phenylalanine and tyrosine derivatives with dicyanoarenes afford glycine derivatives by the generation of radical cations. Despite the limited substrate scope, the radical cation of phenylalanine and tyrosine derivatives bearing both a carbamate (without an aromatic group) at the N-terminal and an amide at the C-terminal could promote the breaking C–C bond at the benzylic position by a photoinduced electron transfer. It is important to understand the chemical behavior of the radical cations of phenylalanine and tyrosine in enzymes involving electron transfer.

    更新日期:2017-11-13
  • Microwave-assisted synthesis of hydroxymethyl ketones using azolium-2-carboxylate zwitterions as catalyst precursors
    Tetrahedron (IF 2.651) Pub Date : 2017-11-11
    Evanthia Papadaki, Lionel Delaude, Victoria Magrioti

    Following an initial screening of six common imidazolium, imidazolinium, and dithiolium salts in the presence of a base, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IDip) and 1,3-dimesitylimidazolin-2-ylidene (SIMes) were identified as promising organocatalysts for the microwave-assisted synthesis of hydroxymethyl ketones from aldehydes and paraformaldehyde. The azolium-2-carboxylate zwitterions IDip·CO2 and SIMes·CO2 were then tested as single-component N-heterocyclic carbene (NHC) precursors in the hydroxymethylation of heptanal and benzaldehyde. The latter adduct was an efficient precatalyst for the two reactions. It was successfully applied to a broad range of aliphatic and aromatic substrates (14 examples, 10–97% yields).

    更新日期:2017-11-13
  • Synthesis of N-heterocyclic carbene-Pd(II) complexes and their catalytic activity in the Buchwald-Hartwig amination of aryl chlorides
    Tetrahedron (IF 2.651) Pub Date : 2017-11-11
    Zhi-Mao Zhang, Yu-Jue Gao, Jian-Mei Lu

    Novel N-heterocyclic carbene-palladium(II) complexes using 2-picolinic acid as the ancillary ligand have been successfully developed under mild conditions. Their catalytic activity in organic synthesis has been initially tested in the Buchwald-Hartwig amination of secondary and primary amines with aryl chlorides. Various substituents on both substrates can be tolerated, giving the desired coupling products in good to almost quantitative yields. The minimum catalyst loading can be 0.01 mol%, implying their potential application toward industrial processes.

    更新日期:2017-11-13
  • Synthesis and properties of microenvironment-sensitive oligonucleotides containing a small fluorophore, 3-aminobenzonitrile or 3-aminobenzoic acid
    Tetrahedron (IF 2.651) Pub Date : 2017-11-11
    Hiroaki Ozaki, Takeshi Kawai, Masayasu Kuwahara

    Two C-nucleosides bearing small fluorescent groups as a base were synthesized by Heck-type coupling reaction and incorporated into DNA. They exhibited environment-sensitive fluorescence and opposite solvatochromic properties. The modified DNAs containing 3-aminobenzonitrile or 3-aminobenzoic acid retained the duplexes and their fluorescence reflected the microenvironment.

    更新日期:2017-11-11
  • A novel, three-component reaction to the synthesis of 3-amino-4-cyano-5-aryl-1H-pyrrole-2-carboxamides
    Tetrahedron (IF 2.651) Pub Date : 2017-11-11
    Bagher Mohammadi, Bahareh Rezaei Khorrami, Mahdi Ghorbani, Michal Dusek

    This work described a novel and efficient synthesis of 3-amino-4-cyano-5-phenyl-1H-pyrrole-2-carboxamides. The synthesis was carried out via a simple three-component reaction between arylidenmalononitrile, malononitrile and hydroxylamine hydrochloride in solvent-free conditions. Short reaction times, good to excellent yields of products, inexpensive and readily available starting material, and time and energy saving are the main advantages of this method. The structures of the products were confirmed by 1HNMR, 13CNMR, IR and single crystal X-ray analysis.

    更新日期:2017-11-11
  • A spiropyran with enhanced fluorescence: A bright, photostable and red-emitting calcium sensor
    Tetrahedron (IF 2.651) Pub Date : 2017-11-10
    Georgina M. Sylvia, Sabrina Heng, Akash Bachhuka, Heike Ebendorff-Heidepriem, Andrew D. Abell

    A rationally designed, pyrene-spiropyran hybrid Ca2+ sensor (Py-1) with enhanced fluorescence intensity compared to a standalone spiropyran analogue is presented. Importantly, Py-1 retains the characteristic red emission profile of the spiropyran, while fibre-based photostability studies show the sensor is stable after multiple cycles of photoswitching, without any sign of photodegradation. Such properties are of real advantage for cell-based sensing applications. An interesting observation is that, Py-1 presents with two excitation options; direct green excitation (532 nm) of the photoswitch for a red emission, and UV excitation (344 nm) of the component pyrene, which gives rise to distinct blue and red emissions. This proof-of-concept hybrid sensing system presents as a more general approach to brighter spiropyran-based sensors.

    更新日期:2017-11-11
  • Metal-free one-pot synthesis of benzofurans with ynones and quinones through aza-Michael/Michael/annulation sequence
    Tetrahedron (IF 2.651) Pub Date : 2017-11-10
    Hai-Lei Cui, Hui-Qing Deng, Jin-Ju Lei

    A convenient metal-free one-pot synthesis of benzofuran derivatives starting from simple ynones has been developed. Various functionalized benzofurans closely related to bioactive molecules can be obtained in moderate to good yields (up to 90%) through aza-Michael/Michael/annulation sequence. Preparative scale synthesis of benzofurans has also been successfully achieved. The application of the benzofuran products has been shown by easy transformations to highly functionalized molecules holding significant promise for medicinal chemistry and organic material chemistry.

    更新日期:2017-11-10
  • Transition-metal-free direct trifluoromethylthiolation of electron-rich aromatics using CF3SO2Na in the presence of PhPCl2
    Tetrahedron (IF 2.651) Pub Date : 2017-11-10
    Xia Zhao, Xiancai Zheng, Miaomiao Tian, Jianqiao Sheng, Yifan Tong, Kui Lu

    A novel transition metal-free route for the direct trifluoromethylthiolation of electron-rich aromatics using CF3SO2Na in the presence of PhPCl2 was developed. More specifically, PhPCl2 was used as both a reducing and a chlorinating reagent for the first time in this CF3SO2Na-based trifluoromethylthiolation reaction. The absence of transition metals and the use of cheap and readily available reagents render this method an alternative and practical strategy for the trifluoromethylthiolation of electron-rich aromatics.

    更新日期:2017-11-10
  • Selective reaction of benzyl alcohols with HI gas: Iodination, reduction, and indane ring formations
    Tetrahedron (IF 2.651) Pub Date : 2017-11-10
    Shoji Matsumoto, Masafumi Naito, Takehisa Oseki, Motohiro Akazome, Yasuhiko Otani

    Reactions of benzyl alcohols with HI in solvent-free conditions were examined. Three types of reactions (iodination, reduction, and ring formation) occurred depending on the degree of crowding around the benzyl position and the benzylic stabilization of substrates. Results also showed that the ring formation to give indanes proceeded efficiently when HI was used, and that compounds with electron-rich aromatic rings gave indane derivatives in good yields.

    更新日期:2017-11-10
  • Design and synthesis of novel 1,4-benzodiazepine surrogates as potential CCKA and CCKB antagonists via palladium-catalyzed three-component cascade reactions
    Tetrahedron (IF 2.651) Pub Date : 2017-11-08
    H. Ali Dondas, Samet Belveren, Samet Poyraz, Ronald Grigg, Colin Kilner, Marcos Ferrándiz-Saperas, Elisabet Selva, José M. Sansano

    Structurally diverse novel 1,4-benzodiazepine analogues related to selective CCKA antagonist MK-329, and CCKB antagonists L-365,260 and YM022 are prepared via palladium-catalyzed three component domino reactions involving allenylation-carbonylation-anion capture in one-pot cascade protocol in good to excellent yields.

    更新日期:2017-11-10
  • Sesquiterpenes from a deep-sea-derived fungus Graphostroma sp. MCCC 3A00421
    Tetrahedron (IF 2.651) Pub Date : 2017-11-08
    Siwen Niu, Chun-Lan Xie, Tianhua Zhong, Wei Xu, Zhu-Hua Luo, Zongze Shao, Xian-Wen Yang

    Two structurally corrected sesquiterpenes (1 and 2) and nine new ones (3–11) were isolated from Graphostroma sp. MCCC 3A00421, a deep-sea-derived fungus obtained from hydrothermal sulfide deposits of the Atlantic Ocean. Their structures were elucidated mainly by extensive analyses of NMR and MS spectroscopic data, and their absolute configurations were determined by Cu-Kα single-crystal X-ray diffraction, the modified Mosher's method, as well as ECD spectra. Xylariterpenoid E (3) is the first example of trinor-bergamotane and graphostromabisabol B (11) is the first trinor-bisabolane found in nature. Interestingly, khusinol B (6) exhibited significant anti-inflammatory effect with IC50 value of 17 μM, which was stronger than that of the positive control, aminoguanidine, whose IC50 value was 23 μM. In addition, it also showed weak anti-allergic effect (IC50 = 150 μM).

    更新日期:2017-11-10
  • Synthesis of ferrocene substituted dihydrofuran derivatives via manganese(III) acetate mediated radical addition-cyclization reactions
    Tetrahedron (IF 2.651) Pub Date : 2017-11-08
    Hakan Aslan, Atilla Öktemer, Hakan Dal, Tuncer Hökelek

    In this study, the manganese(III) acetate mediated radical addition-cyclization reactions of ferrocene substituted alkenes and active methylene compounds were carried out. The regio- and stereoselective radical cyclization reactions of (E)-styrylferrocene (1a) and active methylene compounds (2a-g) gave trans-5-ferrocenyl-4-phenyl-4,5-dihydrofuran compounds as the sole products. The reactions of 1-ferrocenyl-1-aryl(heteroaryl)ethenes (1b-e) and active methylene compounds (2a-f) via Mn(OAc)3 led to furan and benzofuran derivatives (10–33) in mid-good yields (up to 75%). Surprisingly, ferrocene substituted allylidene derivatives were obtained from the Mn(OAc)3 mediated reactions of 1-aryl-1-ferrocenylethene (1b-d) and 1,3-dimethylbarbituric acid (2g). The uses of ferrocene substituted alkenes in manganese(III) acetate mediated radical reactions is the first example in this field as far as we know.

    更新日期:2017-11-10
  • Total synthesis of (+)-epiquinamide and (−)-epiepiquinamide from D-mannose
    Tetrahedron (IF 2.651) Pub Date : 2017-11-08
    Withsakorn Sangsuwan, Boonsong Kongkathip, Pitak Chuawong, Ngampong Kongkathip

    The total synthesis of (+)-epiquinamide and (−)-epiepiquinamide has been achieved starting from a 3,5-dihydroxyfuranoside synthon derived from d-mannose. The methods featured Bernet-Vasella reaction followed by Horner-Wadsworth-Emmons (HWE) reaction to provide a new chiral building block diene as the key steps. The bicyclic framework of this quinolizidine was constructed by using ring-closing metathesis, selective reduction of ester and intramolecular nucleophilic substitution-cyclization.

    更新日期:2017-11-10
  • Facile TMSOI catalysed stereoselective synthesis of 2-Methylene selanyl-4-chromanols and anti-cancer activity
    Tetrahedron (IF 2.651) Pub Date : 2017-11-07
    Debayan Sarkar, Sagarika Behera, Sarbani Ashe, Bismita Nayak, Saikat Kumar Seth

    In the present study, a catalytic synthesis of 2-methylene selanyl-4-chromanols has been described. The manuscript highlights a facile Trimethylsulphoxonium iodide (TMSOI) catalysed intramolecular 6-exo-trig coupling reaction in metal-free environment. The reaction exhibits satisfactory yields in presence of multiple free -hydroxyl groups. A stereoselective generation of syn-3-hex-yne-1,5diols has been explored. The relative stereochemistry has been confirmed by single-crystal X-ray of crystalline-selanyl-chromanols. To determine the anticancer efficacy of the synthesized compounds, cell viability assay using MTT was performed against MCF-7 breast cancer cell line. Notably, Compound 9j (IC50 = 3.157 μmol) was found to exhibit potent cytotoxic activity. Compounds 9a and 9e also showed activity with IC50 values of 31.60 ± 4.012 and 36.797 ± 2.72 μmol respectively highlighting the potential of the synthesized compounds as novel lead molecules for future development of potent anti-cancer therapeutics.

    更新日期:2017-11-10
  • Recent advances in catalytic C−H borylation reactions
    Tetrahedron (IF 2.651) Pub Date : 2017-11-06
    Liang Xu, Guanghui Wang, Shuai Zhang, Hong Wang, Linghua Wang, Li Liu, Jiao Jiao, Pengfei Li

    In the past decades, the iridium-catalyzed C–H bond borylation and other newly discovered catalytic borylation reactions have received extensive research interests and developed into a practical approach for functionalization of C−H bonds and therefore an effective and versatile tool in synthesis of novel organic materials, natural products and fine chemicals. The advances of this booming field include significant improvements of the venerable iridium-catalyzed borylation and development of other transition-metal, especially remarkable the first-row transition-metal ones catalyzed borylation. More recently, a metal-free catalytic borylation system has been disclosed. These new methodologies has dramatically expanded the substate scope, increased the reaction efficiency, lowered the cost, and more importantly, provided previously unknown complementary chemical and regioselectivity. During these discoveries, novel catalyst design concepts and/or principles have been generated. In this context, this review aims to detail the recent evolution in the exciting research direction, focusing on the discovery and development of new reactivity, new selectivity.

    更新日期:2017-11-10
  • Efficient regioselective approach for polysubstituted benzene derivatives by intermolecular [2+2+2] cyclotrimerization of alkynes
    Tetrahedron (IF 2.651) Pub Date : 2017-11-06
    Yao-I. Wang, Wei-Lun Hsu, Feng-Cheng Ho, Chia-Pei Li, Chaun-Fu Wang, Hsiu-Hui Chen

    We present an important opinion about the electron effect of the intermolecular cyclcotrimerization of unsymmetrical diaryalkynes in the presence of Co2(CO)8 on the production of corresponding 1,2,4-regioisomer or 1,3,5-regioisomer derivatives with excellent yields and high regioselectivity.

    更新日期:2017-11-10
  • Construction of 2,6,9,11-tetraoxatricyclo[6.2.1.03,8]undecane containing 4-keto-D-glucose skeleton
    Tetrahedron (IF 2.651) Pub Date : 2017-11-06
    Ban Fujitani, Kengo Hanaya, Shuhei Higashibayashi, Mitsuru Shoji, Takeshi Sugai

    A unique tricyclic bisacetal, 2,6,9,11-tetraoxatricyclo[6.2.1.03,8]undecane observed in cotylenin A, was constructed in a simplified model compound, based on 6-O-methyl-4-keto-D-glucose as the scaffold to control of the stereochemistry. The key compound was an unprecedented spirolactone formed from the α-(α′-hydroxy)acyloxy dimethyl acetal, accompanied with stereoselective migration of an acyl group. Subsequent intramolecular acetalization between the hydroxy group at the C-3 and the C-1′ hemiacetal position furnished the desired tricyclic bisacetal.

    更新日期:2017-11-10
  • A domino Kornblum-DeLaMare/aza-Michael reaction of 3,6-dihydro-1,2-dioxines and application to the synthesis of the ceramide transport inhibitor (±)-HPA-12
    Tetrahedron (IF 2.651) Pub Date : 2017-11-06
    Sarah V.A.-M. Legendre, Martyn Jevric, Julian Klepp, Christopher J. Sumby, Ben W. Greatrex

    A Kornblum-DeLaMare/aza-Michael reaction of 3,6-dihydro-1,2-dioxines with primary and secondary amines has been developed which affords 4-hydroxy-3-aminoketones. The aza-Michael products were reduced using non-selective NaBH4/MeOH or diastereoselective (up to 92:8) SnCl4/NaBH4 conditions yielding (1R∗,3S∗)-3-amino-1,4-diols in up to 97% and 70% yield respectively. The major reduction product was converted in two steps to (±)-HPA-12, which is an inhibitor of the cytosolic ceramide transporting protein.

    更新日期:2017-11-10
  • Atranones with enhancement neurite outgrowth capacities from the crinoid-derived fungus stachybotrys chartarum 952
    Tetrahedron (IF 2.651) Pub Date : 2017-11-06
    Yong-Fang Li, Pan-Pan Zhang, Su-Jun Yan, Jia-Yi Xu, Shah-Iram Niaz, Raza Chand, Chi Him Eddie Ma, Yong-Cheng Lin, Jing Li, Lan Liu

    Seven new atranones (1–5, 7, 10) and three known analogues (6, 8, 9) were isolated from the marine crinoid-derived toxigenic fungus Stachybotrys chartarum 952. The structures of these compounds were elucidated by spectroscopic analysis as well as X-ray crystallographic analysis and electronic circular dichroism calculations. The absolute configurations of three known compounds 6, 8, 9 were first determined. Compound 8 promoted neurite outgrowth from adult DRG neurons significantly without affecting cell survival at 1 μg/mL concentrations.

    更新日期:2017-11-10
  • Mechanistic study on iodine-catalyzed aromatic bromination of aryl ethers by N-Bromosuccinimide
    Tetrahedron (IF 2.651) Pub Date : 2017-11-02
    Pranab Kumar Pramanick, Zhen-Lin Hou, Bo Yao

    Although iodine-catalyzed reaction has rapid advances in recent years, examples on iodine-catalyzed bromination are rare and the mechanism of these reactions remains unclear. Herein, we reported an I2-catalyzed aromatic bromination of aryl ethers by NBS and presented the details of the mechanistic study including kinetic study and the study of kinetic isotope effects. The study revealed that the reaction was actually catalyzed by IBr formed in the induction period, and the rate-determining step was the HBr-elimination of the Wheland intermediate assisted by IBr.

    更新日期:2017-11-10
  • Syntheses and properties of second-generation V-shaped xanthene dyes with piperidino groups
    Tetrahedron (IF 2.651) Pub Date : 2017-11-05
    Akari Yamagami, Kenichi Kawano, Shiroh Futaki, Kouji Kuramochi, Kazunori Tsubaki
    更新日期:2017-11-05
  • Norbornene probes for the study of cysteine oxidation
    Tetrahedron (IF 2.651) Pub Date : 2017-11-04
    Lisa J. Alcock, Kyle D. Farrell, Mawey T. Akol, Gregory H. Jones, Matthew M. Tierney, Holger B. Kramer, Tara L. Pukala, Gonçalo J.L. Bernardes, Michael V. Perkins, Justin M. Chalker
    更新日期:2017-11-05
  • Effects of core moiety and substituted positions in phenothiazine-based hole transporting materials towards high thermal stability and good hole mobility
    Tetrahedron (IF 2.651) Pub Date : 2017-11-03
    Xiaozhong Liang, Chao Wang, Min Wu, Yuezhen Wu, Fang Zhang, Zhaoxiang Han, Xiaoqing Lu, Kunpeng Guo, Yu-Ming Zhao
    更新日期:2017-11-05
  • Microbial oxidation of harzianone by Bacillus sp. IMM-006
    Tetrahedron (IF 2.651) Pub Date : 2017-11-03
    Min Zhang, Jimei Liu, Ridao Chen, Jinlian Zhao, Kebo Xie, Dawei Chen, Keping Feng, Jungui Dai
    更新日期:2017-11-05
  • Metal-free photocatalyzed cross coupling of aryl (heteroaryl) bromides with isonitriles
    Tetrahedron (IF 2.651) Pub Date : 2017-11-03
    Xiangguang Li, Deqiang Liang, Wenzhong Huang, Huanli Sun, Lvsu Wang, Mengran Ren, Baoling Wang, Yinhai Ma
    更新日期:2017-11-05
  • Exploiting cooperative binding of ion-pair to boost anion recognition in water/acetonitrile mixtures
    Tetrahedron (IF 2.651) Pub Date : 2017-11-03
    Dominika Załubiniak, Joanna Kos, Piotr Piątek
    更新日期:2017-11-05
  • Synthesis of polysubstituted phenyl acetates via FeCl3-mediated domino reaction of 2-(aryl(piperidin-1-yl)methyl)phenols and 1,3-diketones
    Tetrahedron (IF 2.651) Pub Date : 2017-11-02
    Xinwei He, Jiajia Tao, Hui Wang, Xiaoting Cai, Qianqian Li, Yongjia Shang
    更新日期:2017-11-03
  • Facile synthesis of thiophene/selenophene-fused acene and their optoelectronic properties
    Tetrahedron (IF 2.651) Pub Date : 2017-11-02
    Zitang Wei, Xiangchun Li, Fred Wudl, Yonghao Zheng
    更新日期:2017-11-03
  • An unusual [4 + 4] cycloadduct from an o-quinodimethane: Characterisation and computational studies
    Tetrahedron (IF 2.651) Pub Date : 2017-11-02
    Raghunath O. Ramabhadran, Mohamed Husaini bin Abdul Rahman, Steven J. Collier, Richard C. Storr, Roderick W. Bates
    更新日期:2017-11-02
  • The role of polycyclic frameworks in modulating P2X7 receptor function
    Tetrahedron (IF 2.651) Pub Date : 2017-11-01
    Timothy B. Callis, Tristan A. Reekie, James O'Brien-Brown, Erick C.N. Wong, Eryn L. Werry, Nabiha Ellias, William T. Jorgensen, John Tsanaktsidis, Louis M. Rendina, Michael Kassiou
    更新日期:2017-11-02
  • A four step synthesis of violaceic acid
    Tetrahedron (IF 2.651) Pub Date : 2017-11-01
    Alex Cameron, Brendan Fisher, Mark A. Rizzacasa
    更新日期:2017-11-02
  • 更新日期:2017-11-01
  • Me3P-catalyzed addition of hydrogen phosphoryl compounds P(O)H to electron-deficient alkenes: 1 to 1 vs 1 to 2 adducts
    Tetrahedron (IF 2.651) Pub Date : 2017-10-31
    Tian-Zeng Huang, Tieqiao Chen, Yuta Saga, Li-Biao Han
    更新日期:2017-11-01
  • Synthesis of a new class of heterocycles 1,7-dithia-3,5-diazacycloalkan(e)-4-(thi)ones using Cs- and Rb-containing catalysts
    Tetrahedron (IF 2.651) Pub Date : 2017-10-29
    Regina R. Khairullina, Alfiya R. Geniyatova, Tatyana V. Tyumkina, Diana S. Karamzina, Askhat G. Ibragimov, Usein M. Dzhemilev
    更新日期:2017-10-30
  • CH3CO2H-prompted three components tandem reaction: An efficient and practical approach to trisubstituted pyrrolo[1,2-a]pyrazines
    Tetrahedron (IF 2.651) Pub Date : 2017-10-28
    Xianglong Chu, Zeyuan Zhang, Congcong Wang, Xuan Chen, Bin Wang, Chen Ma
    更新日期:2017-10-28
  • Fullerene bisadduct regioisomers containing an asymmetric diamide tether
    Tetrahedron (IF 2.651) Pub Date : 2017-10-28
    Tatjana J. Kop, Jelena Đorđević, Mira S. Bjelaković, Dragana Milić
    更新日期:2017-10-28
  • Iron porphyrin-catalyzed C(SP3) -H activation for the formation of C single bond O bond via cross-dehydrogenative coupling of cycloether and aromatic acid
    Tetrahedron (IF 2.651) Pub Date : 2017-10-28
    Wei-Hong Wen, An-Na Xie, Hua-Hua Wang, Dong-Xu Zhang, Atif Ali, Xiao Ying, Hai-Yang Liu
    更新日期:2017-10-28
  • Multicomponent Mannich reactions: General aspects, methodologies and applications
    Tetrahedron (IF 2.651) Pub Date : 2017-10-28
    João F. Allochio Filho, Bárbara C. Lemos, Acácio S. de Souza, Sergio Pinheiro, Sandro J. Greco
    更新日期:2017-10-28
  • C4−H alkoxylation of 6-bromoindole and its application to the synthesis of breitfussin B
    Tetrahedron (IF 2.651) Pub Date : 2017-10-28
    Ardalan A. Nabi, Jessica Liyu, Ashley C. Lindsay, Jonathan Sperry
    更新日期:2017-10-28
  • Iodonium metathesis reactions of unreactive aryl iodides
    Tetrahedron (IF 2.651) Pub Date : 2017-10-28
    Léanne Racicot, Marco A. Ciufolini
    更新日期:2017-10-28
  • Oxazonigelladine and dolabellane-type diterpene constituents from Nigella damascena seeds
    Tetrahedron (IF 2.651) Pub Date : 2017-10-25
    Keiko Ogawa, Seikou Nakamura, Yumiko Asada, Masayuki Yamashita, Hisashi Matsuda
    更新日期:2017-10-26
  • A template guided approach to generating cell permeable inhibitors of Staphylococcus aureus biotin protein ligase
    Tetrahedron (IF 2.651) Pub Date : 2017-10-25
    Ashleigh S. Paparella, Jiage Feng, Beatriz Blanco-Rodriguez, Zikai Feng, Wanida Phetsang, Mark A.T. Blaskovich, Matthew A. Cooper, Grant W. Booker, Steven W. Polyak, Andrew D. Abell
    更新日期:2017-10-25
  • Synthesis of phenols by using aryldiazonium silica sulfate nanocomposites
    Tetrahedron (IF 2.651) Pub Date : 2017-10-25
    Amin Zarei, Leila Khazdooz, Hamidreza Aghaei, Mohammad Mehdi Gheisari, Shahrzad Alizadeh, Laleh Golestanifar
    更新日期:2017-10-25
  • A facile one pot C-C and C-N bond formation for the synthesis of spiro-benzodiazepines and their cytotoxicity
    Tetrahedron (IF 2.651) Pub Date : 2017-10-24
    Burri Nagaraju, Jeshma Kovvuri, K. Suresh Babu, Praveen Reddy Adiyala, V. Lakshma Nayak, Abdullah Alarifi, Ahmed Kamal
    更新日期:2017-10-25
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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