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Journal Cover Tetrahedron
  [SJR: 0.991]   [H-I: 189]   [128 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0040-4020
   Published by Elsevier Homepage  [3118 journals]
  • Grayanane diterpenoids with diverse bioactivities from the roots of Pieris
           formosa
    • Authors: Chang-Shan Niu; Yong Li; Yun-Bao Liu; Shuang-Gang Ma; Fei Liu; Li Cui; Hai-Bo Yu; Xiao-Jing Wang; Jing Qu; Shi-Shan Yu
      Pages: 375 - 382
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Chang-Shan Niu, Yong Li, Yun-Bao Liu, Shuang-Gang Ma, Fei Liu, Li Cui, Hai-Bo Yu, Xiao-Jing Wang, Jing Qu, Shi-Shan Yu
      During our continuing study on the roots of Pieris formosa, twelve new grayanane diterpenoids (1–12), together with eight known compounds (13–20), were obtained. Their structures with absolute configurations were characterized by a series of spectroscopic methods and X-ray diffraction. Compounds 1, 2, 4–5, 7–8, 14, and 19 exhibited significant analgesic activity in an acetic acid-induced writhing test. In particular, 7 and 14 were found to be 5 times more potent than morphine in the acetic acid-induced writhing test model. Compounds 1, 4, 9, 13, and 18 showed antifeedant activity against Plutella xylostella at 0.5 mg/mL. Compound 4 exhibited a 38.3% inhibitory effect against the KCNQ2 potassium channel at a concentration of 10 μM.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.018
       
  • Catalyst free, visible-light promoted photoaddition reactions between C60
           and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of
           aminomethyl-1,2-dihydrofullerenes
    • Authors: Suk Hyun Lim; Dae Won Cho; Patrick S. Mariano
      Pages: 383 - 391
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Suk Hyun Lim, Dae Won Cho, Patrick S. Mariano
      An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C60 and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C60, followed by SET from the amine to the triplet excited state of C60. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C60 radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.064
       
  • Alkanoylation of quinazoline by nucleophilic aromatic substitution:
           Combined experimental and computational study
    • Authors: Yumiko Suzuki; Naoto Iwata; Kohei Dobashi; Ryo Takashima; Sundaram Arulmozhiraja; Erika Ishitsubo; Naoya Matsuo; Hiroaki Tokiwa
      Pages: 392 - 400
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Yumiko Suzuki, Naoto Iwata, Kohei Dobashi, Ryo Takashima, Sundaram Arulmozhiraja, Erika Ishitsubo, Naoya Matsuo, Hiroaki Tokiwa
      A combined experimental and computational study on the key intermediates of NHC-catalyzed acylation reaction, Breslow intermediates (BIs), has been conducted in order to achieve a direct nucleophilic alkanoylation of N-heterocycles. Various BI precursors are alternatively prepared and used in the reaction with 4-chloroquinazoline. The present study reveals that the intermediates having benzimidazole moiety serve as acylating agents for the introduction of straight-chain alkanoyl groups. Natural bond orbital analysis indicates that the reactivity of intermediates partly correlates to the occupancy of the π C-C bonds of the hydroxyl enamine moieties. The putative rate-determining step of the acylation reaction has been theoretically investigated. Several new 4-alkanoylquinazolines are synthesized using the BI precursors.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.071
       
  • Catalyst-free concise synthesis of multi-functional 3-cyano-4-quinolinone
           derivatives from cyanoacetylenaminones and DMF-DMA
    • Authors: Xue-Bing Chen; Jia-Wu Gong; Xu-Dong Zhang; Xiu-Lai Liu; Wei Liu; Yong-Chao Wang
      Pages: 401 - 406
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Xue-Bing Chen, Jia-Wu Gong, Xu-Dong Zhang, Xiu-Lai Liu, Wei Liu, Yong-Chao Wang
      An efficient one-pot synthesis of 3-cyano-4-quinolinone derivatives has been developed via the intramolecular cyclization of cyanoacetylenaminones 1 with N,N-dimethylformamide dimethyl acetal (DMF-DMA) 2 under catalyst-free conditions in CH3CN. The reaction offers several advantages, including operational simpleness, easily available starting materials, target molecular diversity, and facile purification. Additionally, the 3-cyano substituted quinolinones may undergo further functionalization and assist in the discovery of novel drugs.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.003
       
  • Synthesis and properties of BF2- & PO2-complexes of mono
           meso-heterocycle substituted 25-oxasmaragdyrins and derivatives
    • Authors: Booruga Umasekhar; Mangalampalli Ravikanth
      Pages: 407 - 417
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Booruga Umasekhar, Mangalampalli Ravikanth
      BF2- and PO2-smaragdyrins containing one five membered heterocycle such as pyrrole, thiophene and furan at one of the meso-position of corresponding 25-oxasmaragdyrins were synthesized by treating the appropriate mono meso-heterocycle substituted 25-oxasmaragdyrin with BF3.OEt2 and POCl3 respectively in CH2Cl2 under mild reaction conditions. All macrocycles were thoroughly characterized by HR-MS and 1D and 2D NMR spectroscopy. The presence of a five membered heterocycle in place of a six membered aryl group significantly alters the electronic properties of the smaragdyrin macrocycle as reflected in their spectral and electrochemical properties. The meso-pyrrole BF2-smaragdyrin was subjected to a Vilsmeier-Haack reaction to prepare meso-(α-formyl pyrrolyl) BF2-smaragdyrin which was subsequently used to prepare meso-(α-dipyrromethanyl pyrrolyl) BF2-smaragdyrin. The further use of meso-heterocycle substituted BF2- and PO2-oxasmaragdyrins was demonstrated by treating meso-pyrrolyl BF2-smaragdyrin with pentafluorobenzaldehyde in CHCl3 under mild acid catalysed conditions to afford an unusual dipyrromethanyl bridged BF2-smaragdyrin dyad which exhibits excellent photophysical properties.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.006
       
  • Stereochemistry in control of photochemical reactivity:
           2,6-Diaryl-4H-spiro[cyclohexane-1,2′-indene]-1′,3′,4-triones
    • Authors: Vladimir Lokshin; Vladimir Khodorkovsky
      Pages: 418 - 424
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Vladimir Lokshin, Vladimir Khodorkovsky
      Photochemical reaction of trans-2,6-diaryl-4H-spiro[cyclohexane-1,2′-indene]-1′,3′,4-triones gives rise to the formation of the ylidenephthalide derivatives as previously observed for 2,2-disubstituted 1,3-indandiones. In contrast, the respective cis-isomers afford different products originating from the unprecedented reversible cyclohexanone cycle breaking (photo-induced retro-Michael reaction). The difference between the reaction pathways does not depend on the irradiation wavelengths or the light source power and is observed both in solution and solid state.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.014
       
  • High-efficiency blue OLEDs based on dendritic dinuclear iridium (III)
           complexes grafted with fluorene core and blue fluorescence chromospheres
    • Authors: Yu Liu; Zhaoran Hao; Haigang Jiang; Yajun Liu; Yafei Wang; Hua Tan; Guohua Xie
      Pages: 425 - 432
      Abstract: Publication date: 18 January 2018
      Source:Tetrahedron, Volume 74, Issue 3
      Author(s): Yu Liu, Zhaoran Hao, Haigang Jiang, Yajun Liu, Yafei Wang, Hua Tan, Guohua Xie
      Two novel dendrimer-like blue-emitting dinuclear cyclometalated iridium (III) complexes, namely (DNaTPA)2DBF(FIrpic)2 and (DPyTPA)2DBF(FIrpic)2, have been successfully synthesized and characterized. In which FIrpic is an iridium (III) bis[(4,6-difluorophenyl)pyridinato-N,C2′]picolate blue-emitting phosphorescent chromophore core, DBF is a 2,7-diphenyl-9H-fluorene bridging core, DNaTPA and DPyTPA are deep blue-emitting fluorescent chromophores composed by rigid high-triplet-energy dendrons of triphenylamine-functionalized naphthalene or pyrene units, and the peripheral dendrons are connected with the ancillary ligand of the emitting core through nonconjugated ether linkage. Their photophysical, thermal, electrochemical, as well as electrophosphorescent properties were primarily studied. Both iridium (III) complexes exhibit high efficient blue emission in solution (38.5% and 19.2%) and a typical FIrpic emission in 1,3-bis(N-carbzolyl)benzene (mCP) matrix (27.0% and 24.1%). Simple bilayer phosphorescent organic light-emitting diodes (PHOLEDs) with a configuration of ITO/PEDOT:PSS/mCP:dopants/TmPyPB/Liq/Al achieved high efficiencies of 12.96 cd/A for current efficiency (CE), 6162 cd/m2 for brightness, 6.22% for external quantum efficiency (EQE), and 3.13 lm/W for power efficiency (PE) with Commission International de L'Eclairage (CIE) coordinates of (0.19 ± 0.01, 0.35 ± 0.02) at only 2 wt% blend of (DNaTPA)2DBF(FIrpic)2. (DPyTPA)2DBF(FIrpic)2-doped devices also reach efficiencies of (9.14 cd/A, 7167 cd/m2, 4.41%, 2.61 lm/W) at the same doping concentration. The results demonstrate that the introduction of dendritic blue-emitting fluorescent chromophore grafted into the blue phosphorescent chromosphere core through nonconjugated linkage is an efficient way to achieve high-efficiency sky-blue emission.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.018
       
  • The potential of achiral sponge-derived and synthetic bromoindoles as
           selective cytotoxins against PANC-1 tumor cells
    • Authors: Nicholas Lorig-Roach; Frances Hamkins-Indik; Tyler A. Johnson; Karen Tenney; Frederick A. Valeriote; Phillip Crews
      Pages: 217 - 223
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): 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.
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      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.029
       
  • Assessment of the regioselectivity in the condensation reaction of
           unsymmetrical o-phthaldialdehydes with alanine
    • Authors: Agathe C.A. D'Hollander; Nicholas J. Westwood
      Pages: 224 - 239
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.035
       
  • Synthesis of a new series of multifunctional dialkyl
           2-(1-(alkylamino)-1,3-dioxo-3-phenylpropan-2-yl)malonates as low molecular
           weight supramolecular organogelators using five-component reaction
    • Authors: Faride Googol; Abbas Rahmati
      Pages: 240 - 252
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Faride Googol, Abbas Rahmati
      Dialkyl 2-(1-(alkylamino)-1,3-dioxo-3-phenylpropan-2-yl)malonates have been synthesized using a one-pot, pseudo five-component condensation reaction of isocyanide, Meldrum's acid, phenylglyoxal and two alcohol molecules in CH2Cl2 at ambient temperature. It was found that these structures could be used as low molecular weight supramolecular organogelators. The gelation behaviors of these organic gelators have been investigated in various organic solvents. The results have shown that dioctyl 2-(1-(cyclohexylamino)-1,3-dioxo-3-phenylpropan-2-yl)malonate in n-dodecane is the best organogelator (0.2 wt%). Scanning electron microscopy and investigation of the rheological properties have indicated that gelator molecules create three dimensional networks via entangling self-assembled micro- and nano-rods. Hence the organogelation is induced by trapping solvent molecules in nano- and micro-spaces in the gel network.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.040
       
  • Palladium-catalyzed allylation and deacylative allylation of
           3-acetyl-2-oxindoles with allylic alcohols
    • Authors: Aitor Ortega-Martínez; Rocco de Lorenzo; José M. Sansano; Carmen Nájera
      Pages: 253 - 259
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Aitor Ortega-Martínez, Rocco de Lorenzo, José M. Sansano, Carmen Nájera
      The Pd-catalyzed allylation of 3-acetyl-2-oxindoles with allyl alcohol is performed using 3 mol% of Pd(dba)2, rac-BINAP and BINOL phosphoric acid as catalytic mixture. This procedure allows the in situ synthesis of 3-allyl-2-oxindole by adding Triton B to the reaction mixture. The deacylative allylation of 3-acetyl-3-methyl-2-oxindoles with allylic alcohols is carried out with 3 mol% of Pd(OAc)2, dppp and 1.5 equiv. of LiOtBu as base affording the corresponding 3,3-disubstituted 2-oxindoles in good yields. Both methodologies can be combined for the preparation of unsymmetrical 3,3-diallylated 2-oxindoles such as compound 7. The DaA must be carried out in the absence of oxygen in order to avoid the competitive formation of 3-alkyl-3-hydroxy-2-indoles. The later compounds can be easily obtained by deacylative oxidation of 3-alkylated 3-acetyl-2-oxindoles with LiOEt at rt under air.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.041
       
  • Levopimaric acid derived 1,2-diamines and their application in the
           copper-catalyzed asymmetric Henry reaction
    • Authors: Tatiana B. Khlebnikova; Vasily N. Konev; Zinaida P. Pai
      Pages: 260 - 267
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Tatiana B. Khlebnikova, Vasily N. Konev, Zinaida P. Pai
      Levopimaric acid, a readily available starting material, was used in efficient syntheses of new enantiopure diamines and Schiff bases with good yields. The synthetic procedure is based on the fumaropimaric acid monomethyl ester conversion into the optically pure trans-1,2-diamine via a Curtius rearrangement. New diamines were studied as ligands in the copper-catalyzed asymmetric Henry reaction.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.059
       
  • Chiral 2-(2-hydroxyaryl)alcohols (HAROLs) with a 1,4-diol scaffold as a
           new family of ligands and organocatalysts
    • Authors: Ömer Dilek; Mustafa A. Tezeren; Tahir Tilki; Erkan Ertürk
      Pages: 268 - 286
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Ömer Dilek, Mustafa A. Tezeren, Tahir Tilki, Erkan Ertürk
      Efficient and modular syntheses of chiral 2-(2-hydroxyaryl)alcohols (HAROLs), novel 1,4-diols carrying one phenolic and one alcohol hydroxyl group, have been developed which led to generation of a small library of structurally diverse HAROLs in enantiomerically pure form. Of the different HAROLs examined, a HAROL based on the indan backbone exhibited the highest activity and enantioselectivity in the 1,2-addition of certain organometallic compounds to aldehydes in the presence of Ti(O i Pr)4 (up to 97% y, 88% ee) and performed as a hydrogen-bond donor organocatalyst in the Morita-Baylis-Hillman reaction, promoted by trialkylphosphines.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.054
       
  • Substituents modification of meso-aryl BODIPYs for tuning photophysical
           properties
    • Authors: Sangwon Ko; Cheul Yong Kim; Kongara Damodar; Hyun Min Lim; Jin Ho Kim; Chang-Hee Lee; Jeong Tae Lee
      Pages: 287 - 295
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Sangwon Ko, Cheul Yong Kim, Kongara Damodar, Hyun Min Lim, Jin Ho Kim, Chang-Hee Lee, Jeong Tae Lee
      We successfully synthesized eight meso-aryl BODIPYs with 2,6-diethyl- or 1,2,6,7-tetraethyl substituents and characterized their photophysical properties. The steric hindrance resulting from the phenolic group in the meso-aryl moiety and the ethyl groups on the BODIPY core affected the synthesis of dipyrromethanes as an intermediate as well as the UV–Vis absorption and fluorescence emission of the BODIPYs due to the constrained rotation of the aryl ring. The potential use of the meso-hydroxyphenyl BODIPY as a pH sensor was also shown by the pH-dependent fluorescence emissions.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.061
       
  • Kinetic resolution of sterically hindered secondary alcohols catalyzed by
           aminophosphinite organocatalyst
    • Authors: Nanami Hara; Shu Fujisawa; Mizuki Fujita; Mikako Miyazawa; Kazuma Ochiai; Satoshi Katsuda; Tetsuya Fujimoto
      Pages: 296 - 302
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Nanami Hara, Shu Fujisawa, Mizuki Fujita, Mikako Miyazawa, Kazuma Ochiai, Satoshi Katsuda, Tetsuya Fujimoto
      Kinetic resolution of secondary alcohols by benzoylation using a phosphinite derivative of (1S,2R)-1-amino-2-indanol as the catalyst was investigated. The aminophosphinite catalyst is effective for the kinetic resolution of aryl cycloalkyl carbinols with a small number of examples for organocatalytic kinetic resolution to achieve resolution with s = up to 44. Although the benzoylation of phenylalkanols proceeded with a low selectivity, 1-arylalkanols bearing at least one substituent at the ortho position on the benzene ring or a branched alkyl group on the carbinol carbon were resolved with acceptable selectivity.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.062
       
  • Base-promoted nucleophilic fluoroarenes substitution of CF bonds
    • Authors: Ji Su; Qian Chen; Le Lu; Yuan Ma; George Hong Lok Auyoung; Ruimao Hua
      Pages: 303 - 307
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Ji Su, Qian Chen, Le Lu, Yuan Ma, George Hong Lok Auyoung, Ruimao Hua
      With the use of KOH/DMSO as the superbase medium, the nucleophilic fluoroarene substitution for CF bonds is presented. The transformation proceeds smoothly with the use of fluoroarenes bearing not only electron-withdrawing group, but also electron-donating group and a variety of nucleophiles such as alcohols, phenols, amines, amides and nitrogen-heterocyclic compounds. The double nucleophilic substitution using ortho-difluoroarenes and nucleophiles bearing ortho-dinucleophilic groups results in the formation of 2,3-dihydro-1,4-benzodioxins, dibenzo[b,e][1,4]dioxins and 10H-phenoxazines in moderate to good yields.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.067
       
  • Expansion of the aromatic part of Cinchona alkaloids. Annulation of
           quinolines with phenoxazine motifs
    • Authors: Małgorzata Wąsińska-Kałwa; Mirosław Giurg; Przemysław J. Boratyński; Jacek Skarżewski
      Pages: 308 - 315
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Małgorzata Wąsińska-Kałwa, Mirosław Giurg, Przemysław J. Boratyński, Jacek Skarżewski
      An oxidative cross-coupling strategy for quinoline ring annulation in Cinchona alkaloids has been developed. Key-reaction optimization by changing oxidants and adjusting the nucleophilicity of the 2-aminophenols led to cupreine and cupreidine expanded with the phenoxazinone unit in 56–75% yield. The stereochemical integrity of the obtained alkaloid structures was confirmed by combined experimental and computed CD and NMR data. The conformational study revealed a fast equilibrium of the three conformers, differing in the orientation of the pyrido[a-3,2]phenoxazine moiety.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.072
       
  • Sesterterpenes and phenolic alkenes from the Thai sponge Hyrtios erectus
    • Authors: Wirongrong Kaweetripob; Chulabhorn Mahidol; Siriporn Wongbundit; Pittaya Tuntiwachwuttikul; Somsak Ruchirawat; Hunsa Prawat
      Pages: 316 - 323
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Wirongrong Kaweetripob, Chulabhorn Mahidol, Siriporn Wongbundit, Pittaya Tuntiwachwuttikul, Somsak Ruchirawat, Hunsa Prawat
      Sesterterpene, erectusolide A (1), six phenolic alkenes, erectuseneols A−F (2–7) and nine known compounds, luffalactone (8), luffariolide E (9), (6E)- and (6Z)-neomanoalide 24,25-diacetates (10 and 11), 6,6-dimethylundecane-2,5,10-trione (12), threo- and erythro-cavernosines (13 and 14), (4E,6E)-dehydromanoalide (15), echinoclerodane A (16), were isolated from the marine sponge Hyrtios erectus. Compound 13 was isolated for the first time from a natural source. The structures of these compounds were elucidated on the basis of spectroscopic analysis. The phenolic alkenes 3 and 7, the sesterterpenes 8–11 and 15, and compounds 12–14 were evaluated for cytotoxic activities against six cancer cell lines, MOLT-3, HepG2, HeLa, HuCCA-1, A549, and MDA-MB-231.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.073
       
  • Unexpected products from the reaction of chalcones with cyanoguanidine
    • Authors: Amr Hassan Moustafa; Amer Anwar Amer
      Pages: 324 - 328
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Amr Hassan Moustafa, Amer Anwar Amer
      A new series of unexpected dihydrochalcones DHCs attached with cyanoiminopyrimidine moiety in addition to expected cyanoaminopyrimidines CAMPs were synthesized by efficient and facile method via reaction of cyanoguanidine with chalcone derivatives in the presence of EtONa.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.074
       
  • Synthesis and structure of a chiral areno-bridged [2.4]metacyclophane
    • Authors: Thamina Akther; Md.Monarul Islam; Taisuke Matsumoto; Junji Tanaka; Pierre Thuéry; Carl Redshaw; Takehiko Yamato
      Pages: 329 - 335
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Thamina Akther, Md.Monarul Islam, Taisuke Matsumoto, Junji Tanaka, Pierre Thuéry, Carl Redshaw, Takehiko Yamato
      The reductive coupling reaction of 1,4-bis(3-acetyl-5-tert-butyl-2-methoxyphenyl)butane 3 was carried out using TiCl4-Zn in pyridine followed by a McMurry coupling reaction to afford the compounds anti and syn 1,2-dimethyl[2.4]MCP-1-ene 4. Bromination of 4 with BTMA-Br3 in dry CH2Cl2 afforded the interesting compound 1,2-bis-(bromomethyl)-5,15-di-tert-butyl-8,18-dimethoxy[2.4]MCP-1-ene 6 and consecutive debromination with Zn and AcOH in CH2Cl2 solution afforded the stable solid 5,15-di-tert-butyl-8,18-dimethoxy-1,2-dimethylene[2.4]MCP 7 in 89% yield. Compound 7 was conveniently employed in a Diels–Alder reaction with dimethyl acetylenedicarboxylate (DMAD) to provide 2-(3′,6′-dihydrobenzo)-5,15-di-tert-butyl-8,18-dimethoxy[2.4]MCP-4′,5′-dimethylcarboxylate 8 in good yield. Diels–Alder adduct 8 was converted into a novel and inherently chiral areno-bridged compound [2.4]MCP 9 by aromatization. The chirality of the two conformers was characterized by circular dichroism (CD) spectra of the separated enantiomer which are perfect mirror images of each other.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.11.075
       
  • A novel and practical method for the synthesis of dinotefuran through
           Michael addition of nitromethane to diethyl maleate
    • Authors: Haifeng Li; Lailai Wang
      Pages: 336 - 340
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Haifeng Li, Lailai Wang
      A novel and practical synthesis of dinotefuran 1, featuring a new access to it from known key intermediate (tetrahydrofuran-3-yl)-methanamine 5, has been achieved through Michael addition reaction of nitromethane to diethyl maleate in 6 steps with 45.5% total yield. This synthesis is scalable and hence has high potential for application to further synthetic elaboration on such new neonicotinoid insecticide dinotefuran 1.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.002
       
  • Glabralides A – C, three novel meroterpenoids from Sarcandra glabra
    • Authors: Wan-qiu Yang; Ping Hai; Han Xiao; Yuan Gao; Yun-hai Tao; De-ren Miao; Fei Wang
      Pages: 341 - 347
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Wan-qiu Yang, Ping Hai, Han Xiao, Yuan Gao, Yun-hai Tao, De-ren Miao, Fei Wang
      Glabralides A–C (1–3), three novel meroterpenoids including two unprecedented skeletons were isolated from the whole plants of Sarcandra glabra. Glabralide A (1) represented a unique skeleton of the chalcone-coupled monoterpenoid, bearing a bicyclo [2.2.2] octene core unit with five chiral centers. The structures were established by spectroscopic methods, including 2D NMR experiments, and the absolute configurations were determined using circular dichroic (CD) spectra. The plausible biogenetic pathway for 1 suggested that α-phellandrene was conjugated with chalcone by Diels-Alder cyclization, and for 3 implied that α-phellandrene and o-hydroxy phenylacetate cyclized by an uncommon radical addition and cationic cyclization.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.001
       
  • An efficient route to quinoline-2-carboxylates via a rhodium-catalyzed
           oxidative [5+1] annulation of 2-vinylanilines with α-diazocarbonyl
           compounds
    • Authors: Cong Wang; Qiuping Ding; Qiang Zheng; Ping Bao; Yiyuan Peng
      Pages: 348 - 353
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Cong Wang, Qiuping Ding, Qiang Zheng, Ping Bao, Yiyuan Peng
      A novel rhodium-catalyzed oxidative [5 + 1] annulation of 2-vinylanilines with α-diazocarbonyl compounds for the construction of quinoline-2-carboxylate derivatives has been developed. A series of functional groups such as methyl, methoxy, fluoro, chloro, bromo, cyano, and even thienyl substituents were tolerated well. This methodology has the potential for use in the pharmaceutical industry.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.004
       
  • Cyclization and oxidation of o-bromophenylacetamides for the synthesis of
           oxindoles and isoindigoes
    • Authors: Liang Liu; Lei Song; Yujun Guo; Dewen Min; Tianchao Shi; Wu Zhang
      Pages: 354 - 359
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Liang Liu, Lei Song, Yujun Guo, Dewen Min, Tianchao Shi, Wu Zhang
      N-substituted oxindoles were obtained through a facile KOH/DMSO promoted intramolecular cyclization of o-bromophenylacetamides in good yields. Furthermore, isoindigo derivatives were readily synthesized through sequential intramolecular cyclization, oxidation and condensation of o-bromophenylacetamide in the presence of copper (II) acetate monohydrate, iodobenzene diacetate and KOH/DMSO. This method provides a convenient synthesis of a range of oxindoles and symmetrical biologically important (E)-bisindole-2-ones using o-bromophenylacetamide as sole starting material. The reaction mechanism is elucidated in light of the control experiment results.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.005
       
  • The role of β-cyclodextrin in mediating regioselective
           dimethylaminomethylation of phenol
    • Authors: Wen-Hai Wu; Jiang Duan; Ting Wei; Hai-Yang Tu; Ai-Dong Zhang
      Pages: 360 - 365
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Wen-Hai Wu, Jiang Duan, Ting Wei, Hai-Yang Tu, Ai-Dong Zhang
      Regioselective reactions with supramolecular control are of great interest. Herein, the para-regioselectivity in the Mannich reaction of phenol with formaldehyde and dimethylamine was achieved with the use of β-cyclodextrin (β-CD), giving 4-(N,N-dimethylaminomethyl)phenol (p-AP) as major product. 1H NMR and ITC measurements of the binding of β-CD with the reactants and the products o- and p-AP revealed a new mechanism, in which β-CD includes p-AP instead of phenol to control the reaction regioselectivity. This product-inclusion mechanism is remarkably different to the known reactant-inclusion process.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.007
       
  • Synthesis of 2-alkenyl-3-hydroxyquinolin-4(1H)-ones as promising
           antimicrobial and fluorescent agents
    • Authors: Radim Horák; Lubomír Kvapil; Kamil Motyka; Ludmila Slaninová; Martin Grepl; Kamil Kořistek; Miroslav Urbášek; Pavel Hradil; Miroslav Soural
      Pages: 366 - 374
      Abstract: Publication date: 11 January 2018
      Source:Tetrahedron, Volume 74, Issue 2
      Author(s): Radim Horák, Lubomír Kvapil, Kamil Motyka, Ludmila Slaninová, Martin Grepl, Kamil Kořistek, Miroslav Urbášek, Pavel Hradil, Miroslav Soural
      2-Alkenyl-3-hydroxyquinolin-4(1H)-ones were prepared by the rearrangement of anthranilic acid esters synthesized by two alternative methods. The prepared derivatives were screened for their antimicrobial activities against representative Gram-positive and Gram-negative bacteria, displaying notable minimum inhibitory concentration values against specific strains. The emission spectra of the target quinolines exhibited two well-separated emission bands, and the maximum excitation wavelengths of the selected compounds were detected at relatively high values.
      Graphical abstract image

      PubDate: 2017-12-27T05:09:17Z
      DOI: 10.1016/j.tet.2017.12.010
       
  • An unusual [4 + 4] cycloadduct from an o-quinodimethane:
           Characterisation and computational studies
    • Authors: Raghunath O. Ramabhadran; Mohamed Husaini bin Abdul Rahman; Steven J. Collier; Richard C. Storr; Roderick W. Bates
      Pages: 1 - 5
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Raghunath O. Ramabhadran, Mohamed Husaini bin Abdul Rahman, Steven J. Collier, Richard C. Storr, Roderick W. Bates
      Trapping of a pyrimidinone-derived o-quinodimethane with tetraphenylcyclopentadienone gives a mixture of the [4 + 2] and formal [4 + 4] adducts. Computational studies show that the latter arises by a sequence of [4 + 2] cycloaddition, homolysis, radical recombination to a spiro-tetrahydrofuran and Claisen rearrangement under the thermolytic conditions.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.10.076
       
  • Design and synthesis of novel 1,4-benzodiazepine surrogates as potential
           CCKA and CCKB antagonists via palladium-catalyzed three-component cascade
           reactions
    • Authors: H. Ali Dondas; Samet Belveren; Samet Poyraz; Ronald Grigg; Colin Kilner; Marcos Ferrándiz-Saperas; Elisabet Selva; José M. Sansano
      Pages: 6 - 11
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.017
       
  • Novel methodology for the synthesis of the benz[a]anthracene skeleton of
           the angucyclines using a Suzuki-Miyaura/isomerization/ring closing
           metathesis strategy
    • Authors: Myron M. Johnson; Kennedy J. Ngwira; Amanda L. Rousseau; Andreas Lemmerer; Charles B. de Koning
      Pages: 12 - 18
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.023
       
  • N,N-dimethyl-d-glucosamine as an efficient ligand for copper-catalyzed
           Ullmann-type coupling of N-H heterocycles with aryl halides
    • Authors: Jiao Jiao Wei; Wei Bin Song; Ye Fu Zhu; Bo Le Wei; Li Jiang Xuan
      Pages: 19 - 27
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.027
       
  • Puckering behavior in six new phosphoric triamides containing aliphatic
           six- and seven-membered ring groups and a database survey of analogous
           ring-containing structures
    • Authors: Banafsheh Vahdani Alviri; Mehrdad Pourayoubi; Anahid Saneei; Mojtaba Keikha; Arie van der Lee; Aurélien Crochet; A. Abdul Ajees; Marek Nečas; Katharina M. Fromm; Krishnan Damodaran; Titus A. Jenny
      Pages: 28 - 41
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Banafsheh Vahdani Alviri, Mehrdad Pourayoubi, Anahid Saneei, Mojtaba Keikha, Arie van der Lee, Aurélien Crochet, A. Abdul Ajees, Marek Nečas, Katharina M. Fromm, Krishnan Damodaran, Titus A. Jenny
      The influence of a N heteroatom on the ring conformations of six- and seven-membered aliphatic rings in six new C(O)NHP(O)-based phosphoric triamide structures (analysed by X-ray crystallography) is investigated. Additionally the influence of steric and crystal packing effects is also studied by the analysis of Hirshfeld surfaces. The results are compared to analogous structures with three- to seven- aliphatic membered rings deposited in the Cambridge Structural Database. In the newly determined structures, the six-membered rings only show the near-chair conformation with a maximum deviation of the θ puckering parameter of 4.4° from the ideal chair value of 0°/180°, while the seven-membered rings are found in different conformations such as near-chair, twist chair and twist sofa.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.030
       
  • One-pot synthesis of novel 3,10-dihydro-2H-1,3-oxazepino[7,6-b]indoles via
           1,4-dipolar cycloaddition reaction
    • Authors: Mervat S. Sammor; Ahmad Q. Hussein; Firas F. Awwadi; Mustafa M. El-Abadelah
      Pages: 42 - 48
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.031
       
  • Evidence for involvement of cationic intermediate in epoxidation of chiral
           allylic alcohols and unfunctionalised alkenes catalysed by
           MnIII(quinazolinone) complexes
    • Authors: Murat Çakıcı; Hamdullah Kılıç; Sabri Ulukanlı; Duygu Ekinci
      Pages: 49 - 57
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.034
       
  • Solvent-free, catalyst-free aza-Michael addition of cyclohexylamine to
           diethyl maleate: Reaction mechanism and kinetics
    • Authors: Michal Bláha; Olga Trhlíková; Jiří Podešva; Sabina Abbrent; Miloš Steinhart; Jiří Dybal; Miroslava Dušková-Smrčková
      Pages: 58 - 67
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.033
       
  • Modification of Kagan's amide for improved activity as Chiral Solvating
           Agent in enantiodiscrimination during NMR analysis
    • Authors: Nilesh Jain; Aditya N. Khanvilkar; Sibaprasad Sahoo; Ashutosh V. Bedekar
      Pages: 68 - 76
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.036
       
  • Prenylated indole alkaloids and chromone derivatives from the fungus
           Penicillium sp. SCSIO041218
    • Authors: Bin Yang; Huaming Tao; Xiuping Lin; Junfeng Wang; Shengrong Liao; Junde Dong; Xuefeng Zhou; Yonghong Liu
      Pages: 77 - 82
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.038
       
  • Chemical-epigenetic method to enhance the chemodiversity of the marine
           algicolous fungus, Aspergillus terreus OUCMDZ-2739
    • Authors: Kunlai Sun; Guoliang Zhu; Jiejie Hao; Yi Wang; Weiming Zhu
      Pages: 83 - 87
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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-dimethylchroman-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 K i value of 1.42 μM.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.039
       
  • A new enantioselective synthesis of the four stereoisomers of pallantione,
           the male-produced sex pheromone of Pallantia macunaima (Heteroptera:
           Pentatomidae)
    • Authors: Rafael Augusto Soldi; Daiane Szczerbowski; Paulo Henrique Gorgatti Zarbin
      Pages: 88 - 95
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.043
       
  • First synthetic approach towards K-259-2, a unique calmodulin antagonist
    • Authors: Shyam Basak; Smita Mandal; Dipakranjan Mal
      Pages: 96 - 103
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.037
       
  • Enantioselective approach to indolizidine and quinolizidine scaffolds.
           Application to the synthesis of peptide mimics
    • Authors: Yuanyuan Lu; Sílvia Alujas-Burgos; Cristina Oliveras-González; Laura Vázquez-Jiménez; Pep Rojo; Ángel Álvarez-Larena; Pau Bayón; Marta Figueredo
      Pages: 104 - 116
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.042
       
  • Phloroglucinol derivatives and a chromone glucoside from the leaves of
           Myrtus communis
    • Authors: Naonobu Tanaka; Yuyu Jia; Kanji Niwa; Kiyoshi Imabayashi; Yutaka Tatano; Hideki Yagi; Yoshiki Kashiwada
      Pages: 117 - 123
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Naonobu Tanaka, Yuyu Jia, Kanji Niwa, Kiyoshi Imabayashi, Yutaka Tatano, Hideki Yagi, Yoshiki Kashiwada
      Seven new phloroglucinol derivatives, myrtucommunins A–D (1–4), 6-methylisomyrtucommulone B (5), 4-methylmyrtucommulone B (6), and 2-isobutyryl-4-methylphloroglucinol 1-O-β-d-glucopyranoside (7), and one new chromone derivative, undulatoside A 6′-O-gallate (8), were isolated from the leaves of Myrtus communis (Myrtaceae). Myrtucommunins A–D (1–4) were conjugates of polymethylated acylphloroglucinol and flavonol rhamnoside. The absolute configurations of the rhamnosyl moieties for 1–4 were confirmed to be l in each case by HPLC analyses, while those of the aglycones were assigned by comparisons of the experimental and TDDFT calculated ECD spectra. 6-Methylisomyrtucommulone B (5) and 4-methylmyrtucommulone B (6) were assigned as 6/6/6 tricyclic acylphloroglucinol derivatives with a racemic nature. Antimicrobial activities of 1–8 and related known compounds were evaluated.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.044
       
  • Deracemization of α-monosubstituted cyclopentanones in the presence of a
           TADDOL-type host molecule
    • Authors: Hiroto Kaku; Minami Ito; Mitsuyo Horikawa; Tetsuto Tsunoda
      Pages: 124 - 129
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Hiroto Kaku, Minami Ito, Mitsuyo Horikawa, Tetsuto Tsunoda
      Racemic α-monosubstituted cyclopentanones were converted to optically active forms by a thermodynamically controlled deracemization using TADDOL-type host molecule 1 in alkaline aqueous MeOH. The efficiency of this conversion was strongly influenced by the ratio of the solvent components (H2O/MeOH) and the functionality and architecture of the α-side-chain on the cyclopentanones. For example, (R)-2-(2-benzyloxyethyl)cyclopentanone (9) was obtained in 89% yield with 97% ee using a 7:3 mixture of H2O/MeOH as the solvent. X-ray analytical studies were also carried out and disclosed the nature of this chiral molecular recognition process in the solid phase.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.045
       
  • Synthesis of 2,4,6,8,9,11-hexaaza[3.3.3]propellanes as a new molecular
           skeleton for explosives
    • Authors: Byeongil Lee; Moonyong Shin; Youngran Seo; Myeong Hak Kim; Hye Ryoung Lee; Jin Seok Kim; Kyu-hyun Chung; Dongwon Yoo; Young Gyu Kim
      Pages: 130 - 134
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): 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.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.046
       
  • Novel synthesis of perfluoroalkylated indolizinylphosphonates via a
           DIPEA-promoted one-pot process
    • Authors: Hao Liu; Dong He; Zhenhua Sun; Weimin He; Jing Han; Jie Chen; Hongmei Deng; Min Shao; Hui Zhang; Weiguo Cao
      Pages: 135 - 141
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Hao Liu, Dong He, Zhenhua Sun, Weimin He, Jing Han, Jie Chen, Hongmei Deng, Min Shao, Hui Zhang, Weiguo Cao
      DIPEA-promoted one-pot synthesis of perfluoroalkylated indolizinylphosphonates by the reaction of pyridines 1, bromomethyl ketones 2 with perfluoroalkynylphosphonates 3 is described. This procedure is compatible with a broad range of functional groups in both pyridines and ketones with good yields. The reaction proceeds through a tandem CN bond formation followed by an intramolecular cyclization.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.050
       
  • New pyridinium based ionic dyes for the hydrogen evolution reaction
    • Authors: Dagny D. Konieczna; Harry Biller; Matthias Witte; Wolf Gero Schmidt; Adam Neuba; René Wilhelm
      Pages: 142 - 149
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Dagny D. Konieczna, Harry Biller, Matthias Witte, Wolf Gero Schmidt, Adam Neuba, René Wilhelm
      The presented work comprised the synthesis and characterization of new ionic organic dyes as potential photosensitizer (PS) in the photocatalytic H2 evolution reaction. The presented dyes are consisting of donor-π-acceptor (D-π-A) structures that are commonly used for organic dyes for organic solar cells. The acceptor is based on a cationic pyridinium moiety. Furthermore, a complex was synthesized, in which a D-π-A photosensitizer is linked as ligand to cobaloxime. The latter is a common proton reduction catalyst. The attached ligand enabled a fast intramolecular electron transfer to the cobalt center. The resulted complex showed high stability and potential in the homogeneous photocatalytic H2 evolution reaction. Finally, one ionic dye showed a high activity when combined with TiO2 and Pt in a heterogeneous hydrogen evolution reactions with a TOF of up to 407 h−1.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.053
       
  • One-pot palladium-catalyzed synthesis of functionalized
           10H-pyrido[1,2-a]quinoxalin-10-ones under copper-free conditions
    • Authors: Atena Soozani; Ali Keivanloo; Mohammad Bakherad
      Pages: 150 - 156
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Atena Soozani, Ali Keivanloo, Mohammad Bakherad
      Reactions of 3-substituted-2-chloroquinoxalines, terminal alkynes, and 1,3-dicarbonyl compounds in the presence of palladium catalyst afforded a number of 6,8,9-trisubstituted-10H-pyrido[1,2-a]quinoxalin-10-ones in 60–86% reaction yields. This one-pot protocol provided an efficient, practical, and direct method for the synthesis of pyrido[1,2-a]quinoxalines from readily available starting materials in the absence of a copper salt.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.055
       
  • Green asymmetric synthesis of tetrahydroquinolines in carbon
           dioxide medium promoted by lipophilic bifunctional tertiary amine –
           squaramide organocatalysts
    • Authors: Evgeniya V. Filatova; Olga V. Turova; Albert G. Nigmatov; Sergei G. Zlotin
      Pages: 157 - 164
      Abstract: Publication date: 4 January 2018
      Source:Tetrahedron, Volume 74, Issue 1
      Author(s): Evgeniya V. Filatova, Olga V. Turova, Albert G. Nigmatov, Sergei G. Zlotin
      Novel pseudo-enantiomeric bifunctional tertiary amine-squaramides modified with long-chained alkoxy or polyfluoroalkoxy groups, have been synthesized. They catalyzed the asymmetric double-Michael cascade reactions of o-N-tosylaminophenyl α,β-unsaturated ketones with α-nitroolefins in carbon dioxide medium at significantly lower pressure (75 bar) and temperature (35 °C), than known less lipophilic catalysts. Both enantiomers of the pharmacologically valuable methoxy-substituted tetrahydroquinoline derivatives can be prepared in moderate to high yield with promising enantioselectivity (up to 98% ee) under the optimized conditions.
      Graphical abstract image

      PubDate: 2017-12-11T17:40:14Z
      DOI: 10.1016/j.tet.2017.11.057
       
 
 
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