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Journal Cover Tetrahedron Letters
  [SJR: 0.782]   [H-I: 145]   [124 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0040-4039 - ISSN (Online) 1359-8562
   Published by Elsevier Homepage  [3043 journals]
  • New C2-symmetric six-membered carbene ligands incorporating two hydroxyl
           groups for palladium-catalyzed deprotonative-cross-coupling processes
           (DCCP) of sp3 C–H bonds in diarylmethanes
    • Authors: Bi-Hui Zhou; Chen Wu; Xing-Xiu Chen; Hong-Xia Huang; Lin-Lin Li; Li-Mei Fan; Jie Li
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Bi-Hui Zhou, Chen Wu, Xing-Xiu Chen, Hong-Xia Huang, Lin-Lin Li, Li-Mei Fan, Jie Li
      A series of novel 3,4,5,6-tetrahydropyrimidinium salts, the precursor of N-heterocyclic carbene, were synthesized in high yields using a two-step procedure starting from commercially available amino alcohols. In situ prepared corresponding carbenes were tested in palladium-catalyzed C(sp3)−H arylation of 4-benzylpyridine with aryl bromides, affording triarylmethane derivatives in high yields.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.022
       
  • The influence of distal substitution on the base-induced isomerization of
           long-chain terminal alkynes
    • Authors: Innus Mohammad; JiYoung Mun; Amber Onorato; Martha D. Morton; Abdullah I. Saleh; Michael B. Smith
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Innus Mohammad, JiYoung Mun, Amber Onorato, Martha D. Morton, Abdullah I. Saleh, Michael B. Smith
      When compared to a long-straight chain terminal alkyne, a long chain terminal alkyne with a distal isopropyl unit (isobranched) isomerizes about two times faster when treated with strong base under identical conditions, and appears to follow pseudo first order kinetics. In both cases, equilibration to a 95–97:5–3 mixture of terminal:internal alkyne accompanies isomerization. The difference in rate may be due to an unusual folding of both long-chain alkynes, bringing the distal substituent close to the carbon-carbon-triple bond moiety. The distal isopropyl moiety may provide unanticipated steric hindrance that disrupts such folding, making the propargylic proton more available for reaction with base.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.026
       
  • Synthesis, characterization and biological evaluation of purine nucleoside
           analogues
    • Authors: Shankaraiah Malthum; Naveen Polkam; Tejeswara Rao Allaka; Kalyani Chepuri; Jaya Shree Anireddy
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Shankaraiah Malthum, Naveen Polkam, Tejeswara Rao Allaka, Kalyani Chepuri, Jaya Shree Anireddy
      We present a convenient route for the synthesis of C6-amino-C5′-N-cyclopropyl carboxamido-C2-alkynylated purine nucleoside analogues 11a–g via Sonogashira coupling reaction. The nine step synthesis is easy to perform, employing commercially available reagents. Compound 9 is used as key intermediate for the synthesis of analogues 11a–g. Synthetic intermediates and final products are appropriately characterized by IR, 1H NMR, 13C NMR and Mass. The modified nucleoside analogues 11a–g is evaluated for in vitro anticancer activity against MDA-MB-231 and Caco-2 cell lines. Screening data reveals that compounds 11b and 11e displayed potent IC50 value of 7.9, 6.8µg/mL respectively against MDA-MB-231 and of 7.5, 8.3µg/mL respectively against Caco-2 than the standard drug doxorubicin, thus establishing the potential anti-cancer properties of these newer derivatives.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.041
       
  • [bmIm]OH catalyzed coupling: Green and efficient synthesis of 2,8
           dioxacyclopenta [a] inden-3-one derivatives in an aqua media
    • Authors: Malik A Waseem; Shireen; Khursheed Ansari; Farah Ibad; Afshan Ibad; Jagdamba Singh; I.R. Siddiqui
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Malik A Waseem, Shireen, Khursheed Ansari, Farah Ibad, Afshan Ibad, Jagdamba Singh, I.R. Siddiqui
      An efficient recyclable [bmIm]OH catalyzed and aqua mediated eco-compatible synthesis of biologically versatile 2,8 dioxacyclopenta [a] inden-3-one derivatives. Combination of ionic liquid and water has emerged out as a powerful synthetic tool for constructing C–C, C–S and C–O bonds. Disclosed methodology for introducing broad range of 2-iodophenols, 2-iodothiophenols and tetronic acid in basic ionic liquid with predictable high yield will catch the attention of synthetic chemists. This protocol has documented the notable advances and the applications of ionic liquid in heterocyclic synthesis. The chosen strategy illustrates important issues regarding scope, reactivity, product yield, reaction time, reuse and recyclability that will help in designing new synthetic routes for other heterocyclic synthesis.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.039
       
  • Analogues of the 2-carboxyl-6-hydroxyoctahydroindole (CHOI) unit from
           diverging Pd-catalyzed allylations: Selectivity as a function of the
           double bond position
    • Authors: Zhongyi Mao; Elisabetta Martini; Guillaume Prestat; Julie Oble; Pei-Qiang Huang; Giovanni Poli
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Zhongyi Mao, Elisabetta Martini, Guillaume Prestat, Julie Oble, Pei-Qiang Huang, Giovanni Poli
      Pd-catalyzed allylations of cyclic bis-allylic substrates, carried out either as two separate steps or in a pseudo-domino fashion, can generate 2-carboxyl-hexahydroindoles bearing an unsaturation in different positions. Sequential homologation, and epoxidation or syn-dihydroxylation steps were investigated to access analogues of the bicyclic 2-carboxyl-6-hydroxyoctahydroindole motif of aeruginosins, a family of peptides displaying serine protease inhibitor activity.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.046
       
  • Al(III) chloride catalyzed multi-component domino strategy: Synthesis of
           library of dihydrotetrazolo[1,5-a]pyrimidines and
           tetrahydrotetrazolo[1,5-a]quinazolinones
    • Authors: Parteek Kour; Varun P. Singh; Brijmohan Khajuria; Tajinder Singh; Anil Kumar
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Parteek Kour, Varun P. Singh, Brijmohan Khajuria, Tajinder Singh, Anil Kumar
      Tetrazolo[1,5-a]pyrimidines are well recognized and valuable scaffolds in drug discovery. In the current manuscript, we demonstrated AlCl3 catalyzed synthesis of series of dihydrotetrazolo[1,5-a]pyrimidines and tetrahydrotetrazolo[1,5-a]quinazolinones via a modified Biginelli type multi-component reaction of 5-aminotetrazole, aldehyde and diverse active methylene components such as acetophenone/alkylacetoacetates/dimedone. This provides an efficient route to construct highly functionalized dihydrotetrazolo[1,5-a]pyrimidines and tetrahydrotetrazolo[1,5-a]quinazolinones directly from readily available starting materials.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.052
       
  • Selective functionalization of cyano-phenyl-2-oxazolines using
           TMPMgCl·LiCl
    • Authors: Leandro A. Bozzini; João H.C. Batista; Murilo B.M. de Mello; Ricardo Vessecchi; Giuliano C. Clososki
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Leandro A. Bozzini, João H.C. Batista, Murilo B.M. de Mello, Ricardo Vessecchi, Giuliano C. Clososki
      Metalated phenyl-2-oxazolines bearing cyano groups can be selectively obtained through the reaction of TMPMgCl·LiCl with the appropriate substrate. Subsequent reaction with different electrophiles furnished the functionalized derivatives in good yields. Density functional theory (DFT) calculations were performed to evaluate the influence of the ring substituents on the acidity of the aromatic hydrogens. Application to the synthesis of novel functionalized phthalides illustrates the great potential of the methodology to the synthesis of bioactive compounds.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.051
       
  • Aerobic oxidation of benzyl alcohols through biosynthesized palladium
           nanoparticles mediated by Oak fruit bark extract as an efficient
           heterogeneous nanocatalyst
    • Authors: Hojat Veisi; Saba Hemmati; Mahnaz Qomi
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Hojat Veisi, Saba Hemmati, Mahnaz Qomi
      In this study, green synthesis of Pd nanoparticles (NPs) is outlined through application of Oak fruit bark extract as a reducing, capping and stabilizing agent. The characteristics and properties of the biosynthesized Pd NPs were revealed by FESEM, EDX, XRD, TEM, UV–Vis, and FT-IR spectroscopies. So that, UV–Vis spectroscopy of the Pd colloidal solution confirmed reduction of Pd ions, and XRD and TEM analysis identified fcc unit cell structure forming 5–7nm spherical Pd NPs. Furthermore, catalytic activity of the prepared catalyst was investigated through aerobic oxidation of alcohols, as model reactions. Catalytic evaluations demonstrated achievement of good yields from primary and secondary benzyl alcohols. In general, the devised synthesis method is advantageous from several perspectives. For example, the synthesized catalysts give high product yields and are efficient, they eliminate the need for surfactant, chemical reductants, ligand and organic solvents, the approach is economically inexpensive, it results in cleaner reaction profiles, application of the simply prepared heterogeneous catalyst is convenient, and the catalyst is recoverable and reusable for at least six times without any significant loss of its catalytic activity.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.057
       
  • One-pot synthesis of ortho-acylphenols by palladium-catalyzed phenol
           C–H addition to nitriles
    • Authors: Tao-Shan Jiang; Bei Gan; Xi Wang; Xiuli Zhang
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Tao-Shan Jiang, Bei Gan, Xi Wang, Xiuli Zhang
      The regioselective one-pot synthesis of ortho-acylphenols via the palladium-catalyzed addition of phenols to nitriles and subsequent hydrolysis is reported. The acylation reaction proceeded smoothly using the Pd(OAc)2/DMSO system and TFA as the additive. This method also provides a direct strategy for the synthesis of a salicylketoxime scaffold.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.062
       
  • Synthesis of functionalized chromene and spirochromenes using
           l-proline-melamine as highly efficient and recyclable homogeneous catalyst
           at room temperature
    • Authors: Sakkani Nagaraju; Banoth Paplal; Kota Sathish; Santanab Giri; Dhurke Kashinath
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Sakkani Nagaraju, Banoth Paplal, Kota Sathish, Santanab Giri, Dhurke Kashinath
      An efficient and recyclable homogeneous catalyst is developed using commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio; 3mol% on total weight) was found to be best catalyst to give the desired products with excellent yields (up to 99%) in very short times (1–15min) at room temperature in DMSO as solvent. The catalyst was recovered by adding EtOAc and reused up to 5 cycles without losing the catalytic activity.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.060
       
  • Preparation and reactivity of sterically encumbered organocatalysts and
           their use in the preparation of (S)-Pregabalin precursors
    • Authors: Mauro Cortigiani; Alberto Tampieri; Claudio Monasterolo; Andrea Mereu; Mauro F.A. Adamo
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Mauro Cortigiani, Alberto Tampieri, Claudio Monasterolo, Andrea Mereu, Mauro F.A. Adamo
      Herein we describe the preparation of a new class of sterically demanding organocatalysts derived from d-fructose and their use, alongside hitherto unreported doubly quaternarised Cinchona ammonium salts, in the Michael reaction of nitromethane with 4-nitro-5-alkenyl-isoxazoles.
      Graphical abstract image

      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.067
       
  • Hydrogenolysis of geminal diazides
    • Authors: Phillip Biallas; Stefan F. Kirsch
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Phillip Biallas, Stefan F. Kirsch
      The complete hydrogenolysis of compounds containing the geminal diazido functionality is described. Using hydrogen over palladium on charcoal, the diazides are reduced, and primary amines are obtained. For example, aminomalonates and glycines are generated in a straightforward manner. A protocol that provides direct access to acetylated amines derived from 2-amino-1,3-diketones in good to excellent yields, via hydrogenation in the presence of acetic anhydride, is also presented.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.066
       
  • Synthesis of symmetrically and unsymmetrically substituted S,S-dialkyl
           phosphonodithioates
    • Authors: David J. Jones; Eileen M. O'Leary; Timothy P. O'Sullivan
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): David J. Jones, Eileen M. O'Leary, Timothy P. O'Sullivan
      Herein, we report the synthesis of a range of S,S-dialkyl phosphonodithioates. Symmetrically substituted analogues were readily prepared from the corresponding phosphonic dichlorides in good to moderate yields, while unsymmetrically substituted variants were obtained by a sequential alkylation-deprotection-alkylation strategy.
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      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.065
       
  • Corrigendum to “Synthesis and biological evaluation of oxoapratoxin E
           and its C30 epimer” [Tetrahedron Lett 58 (33) (2017) 3333–3336]
    • Authors: Ping Wu; Hao Xu; Zhi Li; Yang Zhou; Yingxia Li; Wei Zhang
      Abstract: Publication date: 1 November 2017
      Source:Tetrahedron Letters, Volume 58, Issue 44
      Author(s): Ping Wu, Hao Xu, Zhi Li, Yang Zhou, Yingxia Li, Wei Zhang


      PubDate: 2017-10-10T14:18:34Z
      DOI: 10.1016/j.tetlet.2017.09.059
       
  • Chemical syntheses of the cochliomycins and certain related resorcylic
           acid lactones
    • Authors: Martin G. Banwell; Xiang Ma; Benoit Bolte; Yiwen Zhang; Michael Dlugosch
      Pages: 4025 - 4038
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Martin G. Banwell, Xiang Ma, Benoit Bolte, Yiwen Zhang, Michael Dlugosch
      The cochliomycins (7–12) are a group of six resorcylic acid lactones that have recently been isolated from culture broths of marine fungi found in the South China Sea. These natural products have attracted attention as synthetic targets because of (in certain instances) their novel structural features and their capacities to suppress biofouling. This short review summarizes the synthesis of these and some related compounds that have been reported to date, including those developed in the authors’ laboratories.
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      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.08.021
       
  • Organotin-catalyzed regioselective benzylation of carbohydrate trans-diols
    • Authors: Hengfu Xu; Ying Zhang; Hai Dong; Yuchao Lu; Yuxin Pei; Zhichao Pei
      Pages: 4039 - 4042
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Hengfu Xu, Ying Zhang, Hai Dong, Yuchao Lu, Yuxin Pei, Zhichao Pei
      A convenient approach to regioselective benzylation of carbohydrate trans-diols was developed, where 0.1equiv. of Bu2SnCl2 and 0.1equiv. of TBABr were used as the catalysts and 2.0equiv. of BnCl was used as the benzylation reagent. In most cases, similar or better benzylation regioselectivities and isolated yields were obtained by using catalytic amounts of Bu2SnCl2, rather than stoichiometric amounts of organotin reagents required.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.08.043
       
  • Copper-catalyzed tandem reaction directed toward synthesis of
           
    • Authors: Kotaro Yamaguchi; Shin-ichi Kawaguchi; Motohiro Sonoda; Shinji Tanimori; Akiya Ogawa
      Pages: 4043 - 4047
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Kotaro Yamaguchi, Shin-ichi Kawaguchi, Motohiro Sonoda, Shinji Tanimori, Akiya Ogawa
      A copper-catalyzed tandem reaction with vinyl halides and 2-aminobenzamides has been developed. In this synthetic route, cross-coupling reaction of the amide moiety with vinyl halides initially progresses, followed by hydroamination, to provide 2,2-disubstituted quinazolinone derivatives. Moreover, the tandem reaction is used in a one-pot synthesis beginning with alkyne hydroiodination by PPh3, I2, and H2O.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.001
       
  • The formal synthesis of (+)-15-deoxy-Δ12,14-prostaglandin J2: Controlling
           exo-olefin geometry via SmI2-mediated cyclization
    • Authors: Kazunori Takahashi; Yuichi Arai; Toshio Honda
      Pages: 4048 - 4050
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Kazunori Takahashi, Yuichi Arai, Toshio Honda
      A synthetic approach of (+)-15d-PGJ2 has been developed. The present method features a stereoselective construction of the olefin unit using SmI2-mediated radical cyclization. The resulting cyclic compound was further utilized by efficient introduction of α and ω chains of prostaglandins to achieve enantioselective formal synthesis of (+)-15d-PGJ2.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.002
       
  • Isopropenyl acetate: A cheap and general acylating agent of alcohols under
           metal-free conditions
    • Authors: Andrea Temperini; Lucio Minuti; Tommaso Morini; Ornelio Rosati; Francesca Piazzolla
      Pages: 4051 - 4053
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Andrea Temperini, Lucio Minuti, Tommaso Morini, Ornelio Rosati, Francesca Piazzolla
      Functionalized primary, secondary and tertiary alcohols are efficiently acetylated by isopropenyl acetate and catalytic p-TsOH.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.007
       
  • Ruthenium hydride catalyzed silylvinylation of terminal alkynes under
           ethylene atmosphere at 80psi
    • Authors: Alexandre D.C. Dixon; Robert J. Wilson; Daniel D. Nguyen; Daniel A. Clark
      Pages: 4054 - 4056
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Alexandre D.C. Dixon, Robert J. Wilson, Daniel D. Nguyen, Daniel A. Clark
      The development of methods for the stereoselective synthesis of polysubstituted 1,3-dienes is a challenge to synthetic chemistry. Herein is reported a selective approach for the synthesis of polysubstituted 1,3-dienes using the ruthenium hydride catalyzed intramolecular silylvinylation of alkynes under 80psi of ethylene gas. This strategy affords a single diene isomer, is applicable to substrates with aryl and alkyl substitution at the propargyl and homopropargyl positions, and has been utilized in the synthesis of 5- and 6-membered oxasilacycles.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.023
       
  • New, simple, and efficient method for the synthesis of N-substituted
           4-trifluoromethyl-5-(alkan-1-ol)-pyridin-2(1H)-imines
    • Authors: Mário A. Marangoni; Carlos E. Bencke; Helio G. Bonacorso; Marcos A.P. Martins; Nilo Zanatta
      Pages: 4057 - 4061
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Mário A. Marangoni, Carlos E. Bencke, Helio G. Bonacorso, Marcos A.P. Martins, Nilo Zanatta
      A new, simple, and efficient method for the synthesis a novel series of 1-substituted 4-(trifluoromethyl)-5-(alkan-1-ol)-pyridin-2(1H)-imines from the reaction of 3-(5,6-dihydro-4H-pyran-3-yl)-4,4,4-trifluorobut-2-enenitrile and 3-(4,5-dihydrofuran-3-yl)-4,4,4-trifluorobut-2-enenitrile with primary amines – is described. The products were obtained in 29–82% yield.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.024
       
  • Highly stereoselective asymmetric aldol routes to
           tert-butyl-2-(3,5-difluorophenyl)-1-oxiran-2-yl)ethyl)carbamates: Building
           blocks for novel protease inhibitors
    • Authors: Arun K. Ghosh; Emilio L. Cárdenas; Margherita Brindisi
      Pages: 4062 - 4065
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Arun K. Ghosh, Emilio L. Cárdenas, Margherita Brindisi
      Enantioselective syntheses of tert-butyl ((S)-2-(3,5-difluorophenyl)-1-((S)-oxiran-2-yl)ethyl)carbamate and ((S)-2-(3,5-difluorophenyl)-1-((R)-oxiran-2-yl)ethyl)carbamate are described. We utilized asymmetric syn- and anti-aldol reactions to set both stereogenic centers. We investigated ester-derived Ti-enolate aldol reactions as well as Evans’ diastereoselective syn-aldol reaction for these syntheses. We have converted optically active ((S)-2-(3,5-difluorophenyl)-1-((S)-oxiran-2-yl)ethyl)carbamate to a potent β-secretase inhibitor.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.025
       
  • Trichothiazole A, a dichlorinated polyketide containing an embedded
           thiazole isolated from Trichodesmium blooms
    • Authors: Richard S. Belisle; Christopher W. Via; Tracey B. Schock; Tracy A. Villareal; Paul V. Zimba; Kevin R. Beauchesne; Peter D.R. Moeller; Matthew J. Bertin
      Pages: 4066 - 4068
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Richard S. Belisle, Christopher W. Via, Tracey B. Schock, Tracy A. Villareal, Paul V. Zimba, Kevin R. Beauchesne, Peter D.R. Moeller, Matthew J. Bertin
      Mass spectrometry-guided isolation of the lipophilic extract of Trichodesmium bloom material led to the isolation and structure characterization of a new thiazole-containing di-chlorinated polyketide (1). The structure of 1 was deduced using 1D and 2D NMR analysis, high-resolution mass spectrometry analysis and complementary spectroscopic procedures. Trichothiazole A possesses interesting structural features, such as a terminal alkyne, two vinyl chlorides and a 2,4-disubstituted thiazole. Trichothiazole A showed moderate cytotoxicity to Neuro-2A cells (EC50: 13.3±1.1μM).
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.027
       
  • Concise and efficient synthesis of E-stereoisomers of exo-cyclic
           carbohydrate enones. Aldol condensation of dihydrolevoglucosenone with
           five-membered aromatic aldehydes1 Part 1
    • Authors: Zbigniew J. Witczak; Roman Bielski; Donald E. Mencer
      Pages: 4069 - 4072
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Zbigniew J. Witczak, Roman Bielski, Donald E. Mencer
      Stereoselective synthesis of exocyclic enones 10–17 via a base-catalyzed direct aldol condensation between dihydrolevoglucosenone 1 and heterocyclic aldehydes 2–9 is described. The reaction is performed under mild conditions and is applicable to variety of heterocyclic aldehydes. E-Steroisomers of exo-cyclic enones are the only products. They are very easy to isolate and were formed in good to excellent (72–88%) yield. 1H NMR, 13C NMR analyses provide the structural assignment and absolute stereochemistry of the condensation products. Single-crystal X-ray diffraction of condensation product 12, additionally supports the structural assignment.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.028
       
  • Diisobutylaluminum borohydride: An efficient reagent for the reduction of
           tertiary amides to the corresponding amines under ambient conditions
    • Authors: Rachel A. Snelling; Gabriella Amberchan; Angel Resendez; Chris L. Murphy; Lauren Porter; Bakthan Singaram
      Pages: 4073 - 4077
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Rachel A. Snelling, Gabriella Amberchan, Angel Resendez, Chris L. Murphy, Lauren Porter, Bakthan Singaram
      A synthetically simple mixed metal hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], is easily generated from a 1:1 mixture of borane-dimethylsulfide (BMS) and diisobutylaluminum hydride (DIBAL). The reduction of tertiary amides using (iBu)2AlBH4 is complete within five minutes under ambient conditions and the product tertiary amines were isolated in 70–99% yields by a simple acid-base extraction. This new methodology, reported herein, works well for reduction of tertiary aliphatic and aromatic amides as well as lactams to the corresponding amines and product isolation and purification does not require column chromatography.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.030
       
  • Single and double A3-coupling (aldehyde-amine-alkyne) reaction catalyzed
           by an air stable copper(I)-phosphole complex
    • Authors: José Ricardo Cammarata; Rocío Rivera; Franmerly Fuentes; Yomaira Otero; Edgar Ocando-Mavárez; Alejandro Arce; Juan M. Garcia
      Pages: 4078 - 4081
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): José Ricardo Cammarata, Rocío Rivera, Franmerly Fuentes, Yomaira Otero, Edgar Ocando-Mavárez, Alejandro Arce, Juan M. Garcia
      An air stable copper(I)-phosphole complex, [CuCl{2,5-bis(2-thienyl)-1-phenylphosphole}2] (1), was utilized as a catalyst in single and double A3-coupling reactions for preparing mono- and bi-propargylamines. A variety of aldehydes, amines and terminal alkynes were tested. Most of these reactions led to formation of the expected propargylamines in good yields using low amounts catalyst and obviating both the use of purified reagents as employ of a glovebox.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.031
       
  • Nectrianolins A, B, and C, new metabolites produced by endophytic fungus
           Nectria pseudotrichia 120-1NP
    • Authors: Nanang Rudianto Ariefta; Priska Kristiana; Handojo Hadi Nurjanto; Hiroyuki Momma; Eunsang Kwon; Tatsuya Ashitani; Keitaro Tawaraya; Tetsuya Murayama; Takuya Koseki; Hiroshi Furuno; Narandulam Usukhbayar; Ken-ichi Kimura; Yoshihito Shiono
      Pages: 4082 - 4086
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Nanang Rudianto Ariefta, Priska Kristiana, Handojo Hadi Nurjanto, Hiroyuki Momma, Eunsang Kwon, Tatsuya Ashitani, Keitaro Tawaraya, Tetsuya Murayama, Takuya Koseki, Hiroshi Furuno, Narandulam Usukhbayar, Ken-ichi Kimura, Yoshihito Shiono
      Two sesquiterpene-epoxycyclohexenone conjugates, nectrianolins A (1) and B (2), together with a sesquiterpene, nectrianolin C (3), were isolated from the brown rice culture of Nectria pseudotrichia 120-1NP, an endophytic fungus isolated from Gliricidia sepium. Their structures were determined on the basis of 1D-/2D-NMR spectroscopy and HRESIMS data analyses in combination with chemical means. Nectrianolins A–C (1–3) exhibited cytotoxic activity against both HL60 and HeLa cells.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.032
       
  • Synthesis and computational analysis of conformationally restricted
           [3.2.2]- and [3.2.1]-3-azabicyclic diamines
    • Authors: Sreedhar Reddy Tummalapalli; Rohit Bhat; Craig Waitt; Henk Eshuis; David P. Rotella
      Pages: 4087 - 4089
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Sreedhar Reddy Tummalapalli, Rohit Bhat, Craig Waitt, Henk Eshuis, David P. Rotella
      Conformational restriction is a useful approach for ligand design in organic and medicinal chemistry. This manuscript reports the facile synthesis and in silico conformational analysis of two new diastereomeric [3.2.2]-3-azabicyclic, two new [3.2.1]-3-aza-8-oxy-bicyclic and one new [3.2.1]-3-azabicyclic diamine scaffolds. A conformational analysis of these structures along with calculation of carbon–carbon/carbon–nitrogen bond angles was carried out and compared to those in the flexible 1,3-diaminopropane template upon which they were based. It is of particular importance that these scaffolds have bond lengths and angles that can overlap with low energy conformers of the flexible diamine. Such information is useful for ligand design in organic chemistry and for development of structure activity relationships and in silico screening in medicinal chemistry.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.033
       
  • A selective hydration of nitriles catalysed by a Pd(OAc)2-based system in
           water
    • Authors: Daniel D. Sanz Sharley; Jonathan M.J. Williams
      Pages: 4090 - 4093
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Daniel D. Sanz Sharley, Jonathan M.J. Williams
      In situ formation of a [Pd(OAc)2bipy] (bipy=2,2′-bipyridyl) complex in water selectively catalyses the hydration of a wide range of organonitriles at 70°C. Catalyst loadings of 5mol% afford primary amide products in excellent yields in the absence of hydration-promoting additives such as oximes and hydroxylamines.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.034
       
  • Synthesis of spiroindenyl-2-oxindoles by montmorillonite K-10-catalyzed
           tandem Friedel-Crafts alkenylation/hydroarylation of propargylic alcohols
           with sterically hindered and electron-rich arenes
    • Authors: Hwa Jung Roh; Da Young Seo; Ji Yeon Ryu; Junseong Lee; Jae Nyoung Kim
      Pages: 4094 - 4098
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Hwa Jung Roh, Da Young Seo, Ji Yeon Ryu, Junseong Lee, Jae Nyoung Kim
      Various spiroindenyl-2-oxindoles have been synthesized in a one-pot reaction from isatin-derived propargylic alcohols with sterically hindered and electron-rich arenes such as 2-phenylindole and 1,3,5-trimethoxybenzene. The reaction involved montmorillonite K-10-catalyzed tandem Friedel-Crafts alkenylation and a following hydroarylation of an allene intermediate.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.035
       
  • n-Butyllithium-promoted regioselective elimination of vicinal bis-triflate
           having an adjacent ether oxygen
    • Authors: Noriki Kutsumura; Kota Shibuya; Hitoshi Yamaguchi; Takao Saito
      Pages: 4099 - 4102
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Noriki Kutsumura, Kota Shibuya, Hitoshi Yamaguchi, Takao Saito
      Regioselective elimination of a vicinal bis-triflate having an adjacent ether oxygen functional group has been developed. Considered in the context of our studies of the regioselective elimination of vicinal dibromide, the key to the mechanism involves the electron-withdrawing inductive effect of the neighboring oxygen functional group. Aliphatic vinyl triflate was shown to be effective in Suzuki–Miyaura cross coupling compared with corresponding aliphatic vinyl bromide.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.036
       
  • The intramolecular Diels-Alder vinylthiophen (IMDAV) reaction: An easy
           approach to thieno[2,3-f]isoindole-4-carboxylic acids
    • Authors: Yuriy I. Horak; Roman Z. Lytvyn; Yevhen-Oleh V. Laba; Yuriy V. Homza; Vladimir P. Zaytsev; Maryana A. Nadirova; Tatiana V. Nikanorova; Fedor I. Zubkov; Alexey V. Varlamov; Mykola D. Obushak
      Pages: 4103 - 4106
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Yuriy I. Horak, Roman Z. Lytvyn, Yevhen-Oleh V. Laba, Yuriy V. Homza, Vladimir P. Zaytsev, Maryana A. Nadirova, Tatiana V. Nikanorova, Fedor I. Zubkov, Alexey V. Varlamov, Mykola D. Obushak
      The reaction of readily accessible 3-(thien-2-yl)allylamines with maleic anhydride, followed by a domino sequence involving successive acylation/[4+2] cycloaddition steps, leads to the formation of the thieno[2,3-f]isoindole core. The key step, the intramolecular Diels-Alder vinylaren (IMDAV) reaction, proceeds with high level of diastereoselectivity and with formation of a single diastereoisomer of the target product 4,4a,5,6,7,7a-hexahydro-3aH-thieno[2,3-f]isoindole-4-carboxylic acids in excellent yields. If the reaction is carried out at room temperature, it occurs in 2–3days and the proton migration (H-shift) does not take place at the last stage. In boiling benzene, the reaction is complete after three hours, but in this case a slight impurity of byproducts bearing aromatic thiophene ring – 4a,5,6,7,7a,8-hexahydro-4H-thieno[2,3-f]isoindole-4-carboxylic acids is formed.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.038
       
  • Preparative-scale synthesis of amino coumarins through new sequential
           nitration and reduction protocol
    • Authors: Hemchandra K. Chaudhari; Akshata Pahelkar; Balaram S. Takale
      Pages: 4107 - 4110
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Hemchandra K. Chaudhari, Akshata Pahelkar, Balaram S. Takale
      In contrast to the conventional deleterious approach for nitration (for example HNO3/H2SO4) and for reduction (for example Zn/HCl), we hypothesized that sensitive heterocycles such as coumarins could not withstand with those hard conditions. Hence, while studying this reaction sequence to prepare amino coumarins (which is our ongoing project to synthesize antitubercular coumarin agents), we came across mild and greener reagent for nitration using calcium nitrate (Ca(NO3)2·4H2O; lime nitrate), and reduction using d-glucose. These two mild, chemoselective, high yielding methods are discussed herein.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.040
       
  • A mild halogenation of pyrazoles using sodium halide salts and Oxone
    • Authors: Kathryn L. Olsen; Matthew R. Jensen; James A. MacKay
      Pages: 4111 - 4114
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Kathryn L. Olsen, Matthew R. Jensen, James A. MacKay
      A mild, inexpensive, and operationally simple pyrazole halogenation method utilizing Oxone and sodium halide salts is reported. This work documents 17 examples of alkyl, aryl, allyl, and benzyl substituted 4-chloro and 4-bromopyrazoles, obtained in up to 93% yield. Reactions are performed in water under ambient conditions and generation of organic byproducts is avoided.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.042
       
  • UV–vis and fluorescence detection by receptors based on an
           isophthalamide bearing a phenylethynyl group
    • Authors: Shin-ichi Kondo; Kimihiro Endo; Jun Iioka; Keisuke Sato; Yuka Matsuta
      Pages: 4115 - 4118
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Shin-ichi Kondo, Kimihiro Endo, Jun Iioka, Keisuke Sato, Yuka Matsuta
      We have successfully prepared 5-(2-phenylethynyl)isophathalilc acid as a signaling unit and the corresponding derivatives for an anion receptor 2 and a barbiturate receptor 4. Receptor 2 showed characteristic UV–vis changes and dramatic fluorescence quenching upon the addition of anions and receptor 4 showed UV–vis and an OFF-ON fluorescence changes upon the addition of dibutylbarbituric acid based on the diphenylethyne moiety.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.043
       
  • Two new algal bromophenols from Odonthalia corymbifera
    • Authors: Md. Reazul Islam; Daisuke Mikami; Hideyuki Kurihara
      Pages: 4119 - 4121
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Md. Reazul Islam, Daisuke Mikami, Hideyuki Kurihara
      Two new algal bromophenols, odonthalol and odonthadione, were isolated from the alga Odonthalia corymbifera. Odonthalol was determined as a trimer of brominated hydroxylated benzyl (BHB) units. Three units were connected via ether and methylene bridges. Odonthadione was identified as a hybrid compound of the BHB unit and a unique cyclopentenedione. The cyclopentenedione unit has not been reported from natural origin.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.044
       
  • Asymmetric synthetic approach to a functionalized azabicyclo[3.3.1]nonane
           moiety of (+)-sarain A
    • Authors: Jiao Meng; Yu Wang; Yong Qin; Xiao-Yu Liu
      Pages: 4122 - 4124
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Jiao Meng, Yu Wang, Yong Qin, Xiao-Yu Liu
      This paper describes our efforts toward the asymmetric synthesis of sarain A which led to efficient preparation of a functionalized azabicyclo[3.3.1]nonane moiety. The key to the synthesis relied on a base-catalyzed asymmetric Diels-Alder cycloaddition to establish multiple stereocenters of a highly substituted cyclohexenone unit and a facile intramolecular aza-Michael addition to form the desired bicyclic system.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.045
       
  • Copper-catalyzed regioselective allylic oxidation of olefins via C–H
           activation
    • Authors: Nengbo Zhu; Bo Qian; Haigen Xiong; Hongli Bao
      Pages: 4125 - 4128
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Nengbo Zhu, Bo Qian, Haigen Xiong, Hongli Bao
      A regioselective oxidation of allylic C–H bond to C–O bond catalyzed by copper (I) was developed with diacyl peroxides as oxidants. The oxidation of allylic C–H bond was accomplished with good yield and regioselectivity under mild reaction conditions. This method has a broad substrate scope including cyclic olefins, terminal and internal acyclic olefins and allyl benzene compounds. The reaction proceeds by a radical mechanism as suggested by spin trapping experiments.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.047
       
  • A novel HPQ-based turn-on fluorescent probe for detection of fluoride ions
           in living cells
    • Authors: Zhou Zhao; Xinzhou Bi; Wuxiang Mao; Xiaowei Xu
      Pages: 4129 - 4132
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Zhou Zhao, Xinzhou Bi, Wuxiang Mao, Xiaowei Xu
      2-(2′-Hydroxyphenyl)-4(3H)-quinazolinone (HPQ) has been reported as a precipitating fluorescent molecule with excellent optical properties, such as large Stokes shift and strong fluorescence intensity. HPQF, a novel HPQ-based turn-on probe for localizable detection of fluoride ions, was designed, synthesized and fully characterized by 1H NMR, 13C NMR and HRMS. As a chemogenic fluoride probe, the tert-butyldiphenylsilane moiety of HPQF can be easily cleaved by fluoride. After spontaneous 1,6-elimination, HPQ molecule was generated to emit fluorescence under the excitation light. Further study shows that HPQF exhibited high selectivity and sensitivity for detection of fluoride. In addition, HPQF was utilized for the detection of fluoride in living cells.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.049
       
  • A four-step tandem synthesis of 3,5-diaroyl-4-arylpyrazoles from
           1,3-diaryl-propane-1,3-diketones
    • Authors: Jianlan Zhang; Wenwen Chen; Dayun Huang; Xiaobao Zeng; Xinyan Wang; Yuefei Hu
      Pages: 4133 - 4136
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Jianlan Zhang, Wenwen Chen, Dayun Huang, Xiaobao Zeng, Xinyan Wang, Yuefei Hu
      A novel four-step tandem procedure was developed for efficient synthesis of 3,5-diaroyl-4-arylpyrazoles by simply stirring the mixture of 1,3-diarylpropane-1,3-diketones, TsN3, aqueous MeNH2 and Na2CO3 in DMF at 85°C for 3h.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.050
       
  • N-Halo succinimide-promoted one-pot three-component electrophilic
           cyclization: Facile access to dihalogenated heterocycles under mild
           conditions
    • Authors: Hai-Tao Zhu; Ting-Ting Luo; Shi-Hui Shi; Ni-Ni Zhou; Si-Si Ning; Chen Zhang; Yu-Gang Xiao; Ming-Jin Fan; De-Suo Yang
      Pages: 4137 - 4140
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Hai-Tao Zhu, Ting-Ting Luo, Shi-Hui Shi, Ni-Ni Zhou, Si-Si Ning, Chen Zhang, Yu-Gang Xiao, Ming-Jin Fan, De-Suo Yang
      An effective and concise electrophilic cyclization of 1,4-butynediols, 4-aminobut-2-yn-1-ols, pent-2-yne-1,5-diols, 2-propynolphenols and 2-propynolanilines with N-halo succinimides and trimethylsilyl halides opens a one-pot synthetic access to five- and six-membered dihalogenated heterocycles in moderate to good yields. The optimized cyclization conditions are tolerated with many functional groups.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.053
       
  • Synthesis of bicyclopyrroles with various substituents at the bridging
           positions
    • Authors: Satoshi Ito; Marina Tobata; Minenari Asakura; Yasutaka Shinozaki; Yuuki Iwabe; Lisa Sakamoto; Shun-pei Ito; Makoto Roppongi; Toru Oba
      Pages: 4141 - 4144
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Satoshi Ito, Marina Tobata, Minenari Asakura, Yasutaka Shinozaki, Yuuki Iwabe, Lisa Sakamoto, Shun-pei Ito, Makoto Roppongi, Toru Oba
      Bicyclopyrroles are important synthetic equivalents of isoindoles, which are difficult to synthesize. Using bicyclopyrrole asa starting material, functional organic materials such as benzopyrromethene and benzoporphyrin can be synthesized. However, there are few reports on introducing substituents into bridging positions in bicyclopyrrole. By combining various reactions, we successfully obtained bicyclopyrroles with various substituents at the bridging positions.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.056
       
  • Synthesis of a secretoglobin 3A2 type C (98–139) fragment by Dawson’s
           native chemical ligation
    • Authors: Mariko Kikuchi; Reiko Kurotani; Hiroyuki Konno
      Pages: 4145 - 4148
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Mariko Kikuchi, Reiko Kurotani, Hiroyuki Konno
      A secretoglobin 3A2 type C (98–139) peptide was synthesized by native chemical ligation between 115Ile and 116Cys residues using Dawson’s linker. The peptide-N-acyl-benzimidazolinone-glycine amide, a C-terminal thioesters precursor, was provided from 3-amino-4-(methylamino)benzoic acid. In addition, an N-terminal cysteine fragment, the (116–139) peptide, was prepared by ordinary Fmoc-solid phase peptide synthesis. Native chemical ligation of the (98–115) fragment with the Dawson’s linker and the (116–139) peptide smoothly proceeded to give SCGB3A2 type C (98–139) peptide.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.058
       
  • N-Bromosuccinimide mediated synthesis of triazatruxenes from indoles
    • Authors: Natthawut Toworakajohnkun; Mongkol Sukwattanasinitt; Paitoon Rashatasakhon
      Pages: 4149 - 4152
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Natthawut Toworakajohnkun, Mongkol Sukwattanasinitt, Paitoon Rashatasakhon
      A new synthetic method for triazatruxenes from indoles is developed using N-bromosuccinimide (NBS) as a user-friendly reagent. Major reaction parameters including the amount of NBS, substrate concentration, temperature, addition rate and addition method are investigated. Additional experiments are also conducted in order to gain access toward the reaction mechanism. Compared to the use of Br2 in the conventional method, this reaction requires less reaction time, provides better yields, and displays excellent reproducibility. The reaction can be conveniently performed at 10g scale and it is also applicable to several substituted indoles, benzoindole, and N-alkyl indoles.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.061
       
  • Facile benzofuran synthesis: Palladium-catalyzed carbonylative Suzuki
           
    • Authors: Xinxin Qi; Chao Zhou; Jin-Bao Peng; Jun Ying; Xiao-Feng Wu
      Pages: 4153 - 4155
      Abstract: Publication date: 25 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 43
      Author(s): Xinxin Qi, Chao Zhou, Jin-Bao Peng, Jun Ying, Xiao-Feng Wu
      A palladium-catalyzed carbonylative Suzuki coupling of methyl 2-(2-iodophenoxy)acetates with arylboronic acids has been developed. The reactions were performed under CO gas-free conditions and the obtained products act as a direct precursor for the synthesis of highly functionalized benzofuran derivatives.
      Graphical abstract image

      PubDate: 2017-10-02T03:44:36Z
      DOI: 10.1016/j.tetlet.2017.09.063
       
  • Formal total synthesis of stigmatellin A
    • Authors: J.S. Yadav; G. Revathi; B.V. Subba Reddy
      Pages: 3943 - 3946
      Abstract: Publication date: 18 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 42
      Author(s): J.S. Yadav, G. Revathi, B.V. Subba Reddy
      An efficient and stereoselective approach for the formal total synthesis of Stigmatellin A has been described. The key steps involved in this synthesis are desymmetrization of the bicyclic olefin to introduce two methyl and two hydroxyl chiral centers, Friedel Crafts acylation, regioselective demethylation, Baker-Venkataraman rearrangement and Grubbs cross metathesis.
      Graphical abstract image

      PubDate: 2017-09-25T09:09:46Z
      DOI: 10.1016/j.tetlet.2017.08.048
       
  • A concise synthesis of (+)-botryolide-E and its C-7 epimer
    • Authors: Xiaojing Liu; Ruijiao Chen; Feixia Duan; Junhao Jia; Yuqin Zhou; Xiaochuan Chen
      Pages: 3947 - 3950
      Abstract: Publication date: 18 October 2017
      Source:Tetrahedron Letters, Volume 58, Issue 42
      Author(s): Xiaojing Liu, Ruijiao Chen, Feixia Duan, Junhao Jia, Yuqin Zhou, Xiaochuan Chen
      The first synthesis of (+)-botryolide-E and its C-7 epimer has been achieved in 8 steps from d-Glucono-δ-lactone, and their antibiotic activities were also investigated preliminarily.
      Graphical abstract image

      PubDate: 2017-09-25T09:09:46Z
      DOI: 10.1016/j.tetlet.2017.08.057
       
 
 
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