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Tetrahedron Letters
Journal Prestige (SJR): 0.683
Citation Impact (citeScore): 2
Number of Followers: 141  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0040-4039 - ISSN (Online) 1359-8562
Published by Elsevier Homepage  [3161 journals]
  • 1-Methyl-1H-tetrazol-5-yl (MT) Sulfones in the Julia-Kocienski
           Olefination: Comparison with the PT and the TBT Sulfones
    • Abstract: Publication date: Available online 15 May 2019Source: Tetrahedron LettersAuthor(s): Kaori Ando, Daiki Kawano, Daiki Takama, Yutaka Semii The stability and the stereoselectivity of newly prepared n-pentyl 1-methyl-1H-tetrazol-5-yl (MT) sulfone 1a in the Julia-Kocienski reactions were compared with those of the PT sulfone 1b and the TBT sulfone 1c. The improved stability of the anion derived from the n-pentyl MT sulfone 1a enhanced the efficiency of the olefination reactions and gave higher yields of the product alkenes 3 compared with the PT sulfone 1b. Especially high E-selectivity and high yields were obtained from the reaction with aromatic aldehydes and α,β-unsaturated aldehydes. The selectivity of 1a was not so sensitive to the change of base counter ion compared with the PT sulfone 1b. The reaction of the MT sulfones having either ethyl or a longer alkyl chain also gave E-alkenes selectively in high yields.Graphical abstractGraphical abstract for this article
       
  • A ratio-metric fluorescent sensor design platform with red emission of
           Europium(III) as built-in fluorescence correction
    • Abstract: Publication date: Available online 15 May 2019Source: Tetrahedron LettersAuthor(s): Xuechan Liu, Shiping Zhan, Xiaoge Hu, Xiaolin Zhang A EuIII-containing single molecule BCR-Eu as design platform for ratio-metric fluorescent sensor which includes a blue-emitting coumarin dye, a green-emitting BODIPY fluorophore and a EuIII moiety as the origin of red light has been designed and synthesized. The compound BCR shows only green emission with large stoke shift when excited in 400 nm due to good fluorescence resonance energy transfer from coumarin to BODIPY. After embedding EuIII complexes in the molecule, BCR-Eu exhibits dual emission which is equal in magnitude and independent of each other, when excited at the range of 305-365 nm. An emission from Lanthanide complexes as the stable built-in standard fluorescence peak offers a promising opportunity to enhance the precision of bioimaging and also an ideal design platform for future ratio-metric fluorescent sensor.Graphical abstractGraphical abstract for this article
       
  • Novel coupling reaction between sulfonyl azide and
           N,N,N',N'-tetramethylthiourea
    • Abstract: Publication date: Available online 15 May 2019Source: Tetrahedron LettersAuthor(s): Muhammad Aswad, Junya Chiba, Yasumaru Hatanaka, Takenori Tomohiro The synthesis of sulfonylguanidines from N,N,N',N'-tetramethylthiourea and sulfonyl azides is described. This method serves as an alternative route for generating sulfonylguanidines via the use of stable starting materials.Graphical abstractGraphical abstract for this article
       
  • Unexpected intramolecular nucleophilic cyclization of ureidoacetamide: a
           novel route towards the synthesis of 2, 4, 5-trisubsituted oxazoles
    • Abstract: Publication date: Available online 15 May 2019Source: Tetrahedron LettersAuthor(s): Jianhui Liu, Yawen Dong, Guanglan Li, Xiangting Min, Mustafa Hussain A variety of N, 2-diaryl-2-ureidoacetamide prepared from the condensation of N-aryl-α-aminoamide with potassium cyanate (KOCN) undergo efficient Hendrickson’s reagent-mediated nucleophilic cyclization to afford 2,5-diamine-4-aryloxazoles. The two-step synthesis provides seven target products in yields of 61-78% under mild conditions. This reaction involves an unusual pathway in which the electrophilic amide carbonyl carbon is activated by Hendrickson’s reagent and attacked by a nucleophilic ureido oxygen in a 5-exo-trig O-cycloisomerization.Graphical abstractGraphical abstract for this article
       
  • Efficient and practical synthesis of N-acetyl enamides from ketoximes by
           unique iron catalytic system
    • Abstract: Publication date: Available online 15 May 2019Source: Tetrahedron LettersAuthor(s): Takahiro Kunishige, Daisuke Sawada A new procedure for the iron-catalyzed synthesis of enamides from ketoximes was developed, and its mechanism was proposed. A unique reduction system, with the concerted use of KI and Na2S2O4, was involved. The reaction exhibited a wide substrate scope and gave good yields in a short reaction time. The procedure is operationally simple and also applicable for the large-scale synthesis.Graphical abstractGraphical abstract for this article
       
  • (+)- and (-)-Eurotone A: a Pair of Enantiomeric Polyketide Dimers from a
           Marine-Derived Fungus Eurotium sp. SCSIO F452
    • Abstract: Publication date: Available online 14 May 2019Source: Tetrahedron LettersAuthor(s): Wei-Mao Zhong, Jun-Feng Wang, Xiao-Yi Wei, Qi Zeng, Xia-Yu Chen, Yao Xiang, Xin-Peng Tian, Si Zhang, Li-Juan Long, Fa-Zuo Wang (±)-Eurotone A [(±)-1], a pair of new enantiomeric polyketide dimers, as well as six known biogenetically related polyketides (2-7) were isolated from a marine-derived fungus Eurotium sp. SCSIO F452. Their structures were determined by comprehensive spectroscopic methods, X-ray diffraction and quantum chemical calculations. Compound 1 represented the first pair of spiro-dihydrobenzanthracene enantiomers isolated from marine fungi with their absolute configurations assigned. A plausible biosynthetic pathway involving a key acid-mediated dimerization was proposed for 1. The antioxidative activities of the new enantiomers were evaluated.Graphical abstractGraphical abstract for this article
       
  • Total synthesis and determination of the absolute configuration of
           paralemnolin C and biological studies of eremophilane derivatives
    • Abstract: Publication date: Available online 14 May 2019Source: Tetrahedron LettersAuthor(s): Hideki Abe, Mitsuru Fujimaki, Ena Goto, Akihito Yokosuka, Yoshihiro Mimaki, Toyoharu Kobayashi, Hisanaka Ito The first asymmetric total synthesis of paralemnolin C was achieved. The absolute configuration at C11 of this natural product was determined from the X-ray crystallographic analysis of the epoxide derivative. In addition, biological studies of eremophilane derivatives including paralemnolin C and sagittacin E were carried out.Graphical abstractGraphical abstract for this article
       
  • Graphical abstract TOC
    • Abstract: Publication date: 30 May 2019Source: Tetrahedron Letters, Volume 60, Issue 22Author(s):
       
  • Graphical abstract TOC cont’d
    • Abstract: Publication date: 30 May 2019Source: Tetrahedron Letters, Volume 60, Issue 22Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 30 May 2019Source: Tetrahedron Letters, Volume 60, Issue 22Author(s):
       
  • Confirmation of the stereochemistry of two naturally occurring epimeric
           phenylpropanoids via synthesis: elucidation of hitherto unknown full
           stereostructures
    • Abstract: Publication date: Available online 11 May 2019Source: Tetrahedron LettersAuthor(s): Ipsita Chakraborty, Sandip Chatterjee, Avrajit Manna, Tanurima Bhaumik Herein we report our efforts toward unequivocal assignment of the hitherto unknown absolute configurations of two naturally occurring phenylpropanoids from Abies delavayi and Abies fabri via a combination of chiral pool synthesis and single crystal X-ray analysis which also confirmed their previously reported gross structures with relative stereochemistry. Toward this end we have achieved the first stereodivergent syntheses of threo-(1R,2R)-(−)- and erythro-(1S,2R)-(+)-1-(4-hydroxyphenyl)-1-methoxy-2,3-propanediol. The synthetic threo-isomer was found to be identical to the naturally occurring threo-isomer, while the natural erythro-isomer was postulated to be the enantiomer of the synthetic erythro-isomer.Graphical abstractGraphical abstract for this article
       
  • Stereoselective synthesis of novel functionalized cyclohexanone
           derivatives via the condensation of aromatic aldehydes with acetoacetamide
           and the influence of the ortho-effect and autocondensation
    • Abstract: Publication date: Available online 11 May 2019Source: Tetrahedron LettersAuthor(s): Vladimir L. Gein, Natalia V. Nosova, Andrei N. Yankin, Alina Y. Bazhina, Maksim V. Dmitriev A simple, inexpensive and stereoselective synthesis of novel functionalized cyclohexanone derivatives via the reaction of acetoacetamide with aromatic aldehydes in ethanol at room temperature is described. Additionally, the presence of substituents such as –NO2 and –Cl in the ortho-position of the aldehyde aromatic ring resulted in the formation of novel piperidines. The use of Lewis acids such as iron(III) chloride and bismuth(III) nitrate as catalysts led to autocondensation of acetoacetamide and the formation of 2,4-dimethyl-6-oxo-1,6-dihydropyridine-3-carboxamide.Graphical abstractGraphical abstract for this article
       
  • Peroxide-mediated oxidative coupling of primary alcohols and disulfides:
           synthesis of 2-substituted benzothiazoles
    • Abstract: Publication date: Available online 11 May 2019Source: Tetrahedron LettersAuthor(s): Nathalia B. Padilha, Filipe Penteado, Maria C. Salomão, Eric F. Lopes, Luana Bettanin, Daniela Hartwig, Raquel G. Jacob, Eder J. Lenardão A peroxide-mediated protocol for the synthesis of 2-substituted benzothiazoles was developed, starting from bis(o-aminophenyl) disulfides and primary alcohols. Eleven differently 2-substituted benzothiazoles were prepared in moderate to excellent yields using di-tert-butylperoxide (DTBP) as an oxidant.Graphical abstractGraphical abstract for this article
       
  • Graphical abstract TOC
    • Abstract: Publication date: 23 May 2019Source: Tetrahedron Letters, Volume 60, Issue 21Author(s):
       
  • Graphical abstract TOC cont’d
    • Abstract: Publication date: 23 May 2019Source: Tetrahedron Letters, Volume 60, Issue 21Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 23 May 2019Source: Tetrahedron Letters, Volume 60, Issue 21Author(s):
       
  • Iodine(III)/AlX3-mediated Electrophilic Chlorination and Bromination of
           Arenes. Dual Role of AlX3 (X=Cl, Br) for (PhIO)n Depolymerization and as
           the Halogen Source
    • Abstract: Publication date: Available online 10 May 2019Source: Tetrahedron LettersAuthor(s): Alberto Segura-Quezada, Yuvraj Satkar, Dipak Patil, Narendra Mali, Kazimirez Wrobel, Gerardo González, Ramón Zárraga, Rafael Ortiz-Alvarado, César R. Solorio-Alvarado An efficient chlorination and bromination of arenes mediated by in situ-formed PhI(X)OAlX2 (X= -Cl, -Br), which is proposed as a plausible halogenating species, is described. The proposed dual role displayed by AlX3, enables the iodozylbenzene [(PhIO)n] depolymerization while also acting as the halogen source by transferring the chlorine or bromine atoms to the iodine(III) center. This process allowed the chlorination and bromination of different arenes and heteroarenes under mild and open flask conditions. To the best of our knowledge, this is the first report describing a dual role of aluminum salts applied to the direct C-H chlorination and bromination of arenes.Graphical abstractGraphical abstract for this article
       
  • Fused vs. spiro: kinetic, not thermodynamic preference may direct the
           reaction of α-carbonyl oxonium ylides
    • Abstract: Publication date: Available online 10 May 2019Source: Tetrahedron LettersAuthor(s): Natalia I. Guranova, Dmitry Dar'in, Grigory Kantin, Alexander S. Novikov, Olga Bakulina, Mikhail Krasavin Rh(II)-catalyzed decomposition of certain cyclic α-diazocarbonyl compounds in the presence of cyclic ethers has been shown to give bicyclic ring expansion products. These are thought to arise from a [1,4]-alkyl shift toward the carbonyl oxygen atom and are in contrast with the recently observed spirocyclic products of a Stevens-type [1,2]-alkyl shift within the postulated oxonium ylide intermediate. Quantum chemical calculations performed at the B3LYP/6-31G* level of theory showed that the former reaction pathway (toward fused bicycles) is kinetically preferred.Graphical abstractGraphical abstract for this article
       
  • A novel on-off-on fluorescent chemosensor for relay detection of Fe3+ and
           PPi in aqueous solution and living cells
    • Abstract: Publication date: Available online 9 May 2019Source: Tetrahedron LettersAuthor(s): Wei Wang, Meng Wu, Huimin Liu, Qinglei Liu, Yan Gao, Bing Zhao A novel on-off-on fluorescence chemosensor BP based on benzothiazole for the relay recognition of Fe3+ and PPi was designed and synthesized. The chemosensor BP exhibited a high affinity to Fe3+ in the presence of other competing cations. The resultant BP-Fe3+ showed excellent recognition ability for PPi via Fe3+ displacement approach. The detection limits of BP for Fe3+ and BP-Fe3+ for PPi were estimated to be 2.59×10-8M and 8.47×10-8M, respectively. The low cytotoxicity and good cell-membrane permeability of BP and BP-Fe3+ complex makes them capable of Fe3+ and PPi imaging in living Hep G2 cells.Graphical abstractGraphical abstract for this article
       
  • Et2Zn-mediated Stoichiometric C(sp)-H Silylation of 1-Alkynes
           and Chlorosilanes
    • Abstract: Publication date: Available online 9 May 2019Source: Tetrahedron LettersAuthor(s): Pan Huang, Dawen Xu, Robert M. Reich, Felix Kaiser, Boping Liu, Fritz E. Kühn A first example of an Et2Zn mediated silylation of 1-aklynes is reported. A series of functional groups are tolerated in this reaction. Mechanistic studies support Zn alkynilides as intermediates in the reaction. This reaction protocol provides a practical method for the preparation of alkynylsilanes and expands the application of organometallic zinc in organic synthesis.Graphical abstractGraphical abstract for this article
       
  • A unified, RCM anchored approach to spiro[4.5]decane-based
           sesquiterpenoids: Collective synthesis of (±)-α & β -Vetispirenes,
           (±)-β-Vetivone, (±)-Agarospirol and (±)-Hinesol
    • Abstract: Publication date: Available online 9 May 2019Source: Tetrahedron LettersAuthor(s): Sudhakar Athe, Subhash Ghosh, Goverdhan Mehta Collective syntheses of five spiro[4.5]decane framework bearing sesquiterpenoids, namely, α & β-vetispirenes, β-vetivone, agarospirol and hinesol as well as formal synthesis axenol and gleenol from a readily available precursor cyclohexanone-β-ketoester via the intermediacy of a versatile intermediate (2,10-dimethylspiro[4.5]dec-1-en-6-one) have been accomplished in a concise manner.Graphical abstractGraphical abstract for this article
       
  • Cross-dehydrogenative coupling of 3,6-dihydro-2H-pyrans with
           1,3-dicarbonyls and aryl moieties
    • Abstract: Publication date: Available online 9 May 2019Source: Tetrahedron LettersAuthor(s): Guidong Feng, Chuanxi Sun, Xiaodong Xin, Renzhong Wan, Lei Liu An indium-catalyzed oxidative C–H alkylation and arylation of 4-substituted 3,6-dihydro-2H-pyrans (DHPs) using dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as the oxidant has been developed. The mild and modular cross-dehydrogenative coupling reaction exhibited a broad scope with respect to both DHPs and nucleophilic 1,3-dicarbonyl moieties as well as aryl rings, rapidly providing 2,4-disubstituted DHPs bearing diverse patterns of functionalities at the α position.Graphical abstractGraphical abstract for this article
       
  • An Immobilized Vanadium-Binaphthylbishydroxamic Acid Complex as a Reusable
           Catalyst for the Asymmetric Epoxidation of Allylic Alcohols
    • Abstract: Publication date: Available online 9 May 2019Source: Tetrahedron LettersAuthor(s): Masahiro Noji, Hisako Kondo, Chihiro Yazaki, Hiroaki Yamaguchi, Shun Ohkura, Toshikatsu Takanami An immobilized polymer-supported vanadium-binaphthylbishydroxamic acid (PS-VBHA) has been developed as an efficient, reusable catalyst for the asymmetric epoxidation of allylic alcohols. This PS-VBHA catalyst shows comparable catalytic performance to that of the parent V-BBHA catalyst and can be reused five times without significant loss of enantioselectivity.Graphical abstractGraphical abstract for this article
       
  • Synthesis of β-selenylated ketones via iodine-mediated
           selenylation/1,2-carbon migration sequences of alkenyl alcohols
    • Abstract: Publication date: Available online 9 May 2019Source: Tetrahedron LettersAuthor(s): Yubin Kim, Dae Young Kim An iodine-mediated selenylation/1,2-carbon migration sequences of alkenyl alcohols is described. This approach provides a mild and operationally simple access to the synthesis of β-selenated cyclic ketone derivatives from the coupling reaction of alkenyl alcohols with diselenides.Graphical abstractGraphical abstract for this article
       
  • Design and synthesis of A- and D ring-modified analogues of luotonin A
           with reduced planarity
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Abdulrahman I. Almansour, Raju Suresh Kumar, Natarajan Arumugam, Giulia Bianchini, J. Carlos Menéndez, Dhaifallah M. Al-thamili, Govindasami Periyasami, Mohammad Altaf A small library of A- and D-ring modified luotonin-inspired heterocyclic systems have been synthesised in moderate to good yields following a six-step route that starts from phenylalanine and has the final key stage an intramolecular Povarov reaction of imines obtained from a tetrahydroquinoline-derived alkynyl aldehyde and various arylamines.Graphical abstractA- and D-ring modified luotonin-inspired heterocyclic systems have been synthesized starting from phenylalanine following a six-step route that includes the final key stage an intramolecular Povarov reaction.Graphical abstract for this article
       
  • The tetraalkylammonium-accelerated Norrish-Yang photocyclization of
           2-substituted acetophenones
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Shinji Yamada, Yuki Oshima, Yuka Fujita, Seiji Tsuzuki The tetrabutylammonium-accelerated Norrish-Yang cyclization of 2-ethoxycarbonylmethyloxy- and 2-cyanomethyloxyacetophenones afforded trans-dihydrobenzofuranols in good stereoselectivities through cation-π interactions between the ammonium and the carbonyl and cyano groups. Furthermore, a new type of organocatalyst possessing both conformation-controlling and triplet-sensitizing units was developed, and was found to be effective in accelerating the Norrish-Yang photocyclization of 2-cyanomethyloxyacetophenone.Graphical abstractGraphical abstract for this article
       
  • Synthesis of nucleoside units possessing photoreactive diazirine groups on
           the major and minor groove faces
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Tomoya Wada, Noriko Saito-Tarashima, Mayu Yamada, Yasuko Okamoto, Noriaki Minakawa In this work, we developed and examined photoreactive nucleoside units, which are chemical probes to investigate the interaction between nucleic acids and proteins. Starting with 7-iodo-7-deazaadenosine derivative 5, 7-(3-oxobutyl)-7-deazaadenosine derivative 8 was prepared via a palladium-catalyzed reaction with 3-buten-2-ol. Then, the carbonyl group of 8 was converted into a diazirinyl group to provide the desired Dia7C7A 3. In a similar manner, Dia2A 4 was prepared from 2-iodoadenosine derivative 11. The resulting 3 and 4 were confirmed to form chemically active carbene species via photo-irradiation.Graphical abstractGraphical abstract for this article
       
  • The Rhodium-Catalyzed Selective Oxidative Heck Reaction of Amides with
           Allylic Esters
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Yu-Yuan Hei, Jian-Lan Song, Xin-Chen Zhan, Xing-Guo Zhang, Chen-Liang Deng The Rh-catalyzed direct selective oxidation Heck reaction of benzamides with allylic esters has been developed for the synthesis of amides and isoquinolin-1-ones. According to the functional groups on N-atom, benzamides or isoquinolin-1-ones were synthesized under optimal reaction conditions. The ambient catalytic system has good functional group tolerance, afforded corresponding products in moderate to good yields.Graphical abstractGraphical abstract for this article
       
  • Potential antidiabetic zinc(II) complexes of novel
           5-oxo-2-thioxopyrrolidine derivatives synthesized via an unprecedented
           reaction
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Saya Kawano, Yutaka Yoshikawa, Akihiro Kato, Shoko Higashi, Kyohei Mitani, Hiroyuki Yasui, Yoichi Habata, Shunsuke Kuwahara, Kaname Sasaki, Ryota Saito We have developed a synthetic route to novel ethyl 1-arylmethyl-5-oxo-2-thioxopyrrolidine-3-carboxylates (1a–e) via an unprecedented reaction of ethyl 1-arylmethyl-4-acetoxy-5-oxo-2,5-dihydro-1H-pyrrole-3carboxylates with potassium thioacetate. Synthesized products 1a–e were further converted into their zinc(II) complexes (10a–e), having an S2O2-type coordination mode, that showed improved insulin-mimetic activities compared to ZnSO4, a positive standard, and also the previously reported zinc(II) complexes of ethyl 1-benzyl-4-hydroxy-5-oxo-2,5-dihydro-1H-pyrrole-3-carboxylates with O4-type coordination mode.Graphical abstractGraphical abstract for this article
       
  • Xanthate-mediated synthesis of functional bis(γ-thiolactones)
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Marvin Langlais, Olivier Coutelier, Mathias Destarac A new methodology for the synthesis of bis(γ-thiolactones) including two different routes was developed. Both strategies are based on xanthate-mediated synthesis involving free radical addition to an unsaturated compound followed by thermolysis and thiolactonization steps. The first approach is based on the addition of a xanthate to different dienes whereas the second one uses the addition of a bis(xanthate) to various functional alkenes. These two different pathways led to a series of bis(γ-thiolactones) bearing phosphonated, hydroxy, bromide or boronate groups. This shows great promise for broader access to functional bis(γ-thiolactones) which can be envisioned as high potential building blocks for step-growth polymerization.Graphical abstractGraphical abstract for this article
       
  • Metal Free Oxidative C=C Bond Cleavage: Facile and One-pot Tandem
           Synthesis of Benzothiadiazine 1,1-dioxides
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Aniket S. Karpe, Pratima A. Sathe, Prashant Patil, Bhausaheb N. Patil, Atul C. Chaskar An interesting protocol for the synthesis of benzothiadiazine 1,1-dioxides through iodine-catalyzed one-pot dehomologative oxidation of styrenes and readily available 2-aminobenzenesulfonamide has been developed. Diverse benzothiadiazine 1,1-dioxides were prepared using I2 as a catalyst, TBHP as an oxidant and Na2CO3 as a base. This reliable, metal and ligand free conversion involves dehomologation of styrene to aromatic aldehyde which on subsequent cyclisation affords benzothiadiazine 1,1-dioxides in good yield.Graphical abstractGraphical abstract for this article
       
  • Cooperation of biopolymer chitosan with hydrogen peroxide for
           ipso-hydroxylation of arylboronic acids under green conditions
    • Abstract: Publication date: Available online 8 May 2019Source: Tetrahedron LettersAuthor(s): Eun-Jae Shin, Seong-Ryu Joo, Seung-Hoi Kim Oxidative hydroxylation of arylboronic acids to the corresponding phenolic compounds under metal- and base-free aerobic conditions is successfully demonstrated on a biopolymer support (chitosan or chitosan immobilized onto carbon nanotubes (CNT@Chitosan)). Hydrogen peroxide, as an eco-friendly oxidant, is compatible with the biopolymer supports and provides hydroxylation products in an efficient manner. The CNT@chitosan biopolymer support is particularly interesting for its potential recyclability.Graphical abstractGraphical abstract for this article
       
  • A dipodal thiourea-ionic liquid conjugate system for selective ratiometric
           detection of HSO4 − ion in purely aqueous medium: Application to real
           sample analysis
    • Abstract: Publication date: Available online 4 May 2019Source: Tetrahedron LettersAuthor(s): Deepak Bains, Gagandeep Singh, Narinder Singh A benzimidazolium based thiourea conjugate (IL) receptor has been designed, synthesized and characterized spectroscopically. The prepared receptor (IL) shows the sensitive and selective ratiometric sensing for HSO4− over the other anions as evident by UV–visible absorption and fluorescence spectroscopy. With the addition of HSO4− ion, the parent absorption band of IL in UV–visible absorption at 311 nm was shifted to 261 nm having an isosbestic point at 294 nm, which clearly indicates an interaction between HSO4− ion and the IL. Further, upon excitation at 310 nm, the fluorescence emission of IL at 455 nm was observed. Furthermore, the gradual addition of HSO4− ion results in a drastic decrease in emission at 455 nm and simultaneous appearance of a new emission band at 379 nm with isosbestic point at 430 nm was observed. The binding mechanism of HSO4− with IL was also explored with 1H NMR titration, mass spectrometry and DFT calculations. These studies revealed the involvement of hydrogen bonding with –NH (thiourea) and –CH (benzimidazolium) functionalities towards the recognition of HSO4− ion. The association constant (Ka) and lowest detection limits for HSO4− were determined to be 5.437 × 104 M−1 and 5.0 nM, respectively. The real sample analysis by synthesized sensor probe for HSO4− was also performed which shows the practical applicability of the developed sensor system.Graphical abstractGraphical abstract for this article
       
  • Divergent Synthesis of Oxacyclophenylpropanoids from Biomass-Derived
           Eugenol
    • Abstract: Publication date: Available online 2 May 2019Source: Tetrahedron LettersAuthor(s): Guohui Li, Qingqing Zhang, Wenhao Zhuang, Xi Cheng, Tao-Shan Jiang, Yongping Cai A divergent synthesis of new oxacyclophenylpropanoids from the readily available and biomass-derived starting material eugenol is reported. The synthetic routes feature two important steps, including (i) DDQ-mediated selective oxidation of an allyl group and subsequent Claisen-rearrangement for the formation of key intermediates 1 and 11, and (ii) five-membered or six-membered ring formation via either palladium-catalyzed cyclization or ring-closing metathesis (RCM) strategies.Graphical abstractGraphical abstract for this article
       
  • [1],+[4]thiazin-2-one+O-(tert-butyl)+oximes+in+the+presence+of+K2CO3/SiO2&rft.title=Tetrahedron+Letters&rft.issn=0040-4039&rft.date=&rft.volume=">Novel synthesis of 1,4-thiazin-2-one O-(tert-butyl) oximes and
           benzo[b][1], [4]thiazin-2-one O-(tert-butyl) oximes in the presence of
           K2CO3/SiO2
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Tadashi Aoyama, Kenshiro Tashiro, Mamiko Hayakawa, Shigeru Shimada, Akihiko Ouchi A simple and efficient method was developed for the synthesis of 1,4-thiazin-2-one O-(tert-butyl) oximes and benzo[b][1], [4]thiazin-2-one O-(tert-butyl) oximes from N-tert-butoxy acyl imidoyl bromides and 2-aminothiols in the presence of K2CO3/SiO2. Twenty five novel compounds were readily synthesized in excellent yields using this procedure. The products possessed Z-stereochemistry with regard to the C=N double bond. The reaction proceeded with initial substitution of bromine in the N-tert-butoxy acyl imidoyl bromides by mercapto groups in the presence of K2CO3/SiO2, and subsequent intramolecular Schiff base formation.Graphical abstractGraphical abstract for this article
       
  • Tetramethylguanidine (TMG)-Catalyzed Reductive Spirocyclization of
           Tryptamine Derivatives with Formic Acid as a C1 Synthon
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Hui Han, Lei Fang, Jie Chen, Shang-Dong Yang, Ji-Bao Xia A reductive spirocyclization of tryptamine derivatives with formic acid as a C1 building block has been achieved via dearomatization. The reaction was catalyzed by a commercially available and cost-effective organic base, tetramethylguanidine (TMG). A variety of spiroindolenines were obtained in high yields under mild conditions.Graphical abstractGraphical abstract for this article
       
  • Stable cyclopropene-containing analogs of the amino acid neurotransmitter
           glutamate
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Pratik Kumar, Wei Huang, David Shukhman, Frank M. Camarda, Scott T. Laughlin As a neurotransmitter, the amino acid glutamate has been the subject of efforts to generate structural analogs with unique properties. Here we report a practical, half-gram synthesis of two cyclopropene-containing glutamate analogs. These analogs are stable in solution, in the presence of the biological nucleophile glutathione, upon concentration, and during long-term storage, while maintaining their amenability to photo- or enzyme-caging and reactivity with bioorthogonal reaction partners like s-tetrazine or light-activated tetrazoles.Graphical abstractGraphical abstract for this article
       
  • Metal-Free Synthesis of Novel Indolizines from Chromones and Pyridinium
           Salts via 1,3-Dipolar Cycloaddition, Ring-opening and Aromatization
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Kai-Kai Dong, Qiang Huang A simple, efficient, and economical synthetic approach to construct a variety of stucturally novel indolizines bearing a phenolic hydroxy group has been developed through 1,3-dipolar cycloaddition of chromones and pyridinium salts. The methodology is tolerant of a wide range of functional groups and applicable to library synthesisGraphical abstractGraphical abstract for this article
       
  • An efficient preparation of 1,2-dihydropyridazines through a
           Diels-Alder/palladium-catalysed elimination sequence
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Thomas K. Britten, Geoffrey R. Akien, Paul D. Kemmitt, Nathan R. Halcovitch, Susannah C. Coote A convenient, scalable synthesis of 1,2-dihydropyridazines is presented, based on the Diels-Alder cycloaddition of 1-acetoxy-1,3-butadiene with a variety of azo compounds, followed by a palladium-catalysed elimination. The products are produced on multigram scale and the new method is particularly efficient and atom-economical when compared with previous preparations of 1,2-dihydropyridazines.Graphical abstractGraphical abstract for this article
       
  • Pyrroles from TosMIC and Substituted N-Acyl-2,3-dihydro-4-pyridones: A
           short Access to a 4-Azaisoindole Unit
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Sezgin Kiren, Ayanna M. Brooks, Jada J. Graves We investigated the reactions of substituted N-acyl-2,3-dihydro-4-pyridones with TosMIC reagent under various basic conditions to generate novel pyrrole products. These products were then transformed to substituted azaisoindoles in a couple of steps.Graphical abstractGraphical abstract for this article
       
  • Structure-activity studies of irumamycin type macrolides from
           Streptomyces sp. INA-Ac-5812
    • Abstract: Publication date: Available online 30 April 2019Source: Tetrahedron LettersAuthor(s): Vera A. Alferova, Maxim V. Shuvalov, Roman A. Novikov, Alexey S. Trenin, Lubov G. Dezhenkova, Elena G. Gladkikh, Olda A. Lapchinskaya, Valeriya V. Kulyaeva, Olga P. Bychkova, Elena P. Mirchink, Pavel N. Solyev, Gulnara Kh. Kudryakova, Vladimir A. Korshun, Anton P. Tyurin Three natural glycosylated macrolide compounds, known irumamycin 1 and X-14952B 2, as well as new isoirumamycin 3, were isolated from ethyl acetate mycelium extract of Streptomyces sp. INA-Ac-5812. Structures of the compounds were elucidated using 1D and 2D NMR. Isoirumamycin 3 was found to be an isomer of irumamycin with an 18-membered macrolactone ring instead of 20-membered macrolide in irumamycin. A previously unknown stereo configuration of irumamycin epoxide (C23,C24) and hemiketal (C3,C7) fragments was deduced from NMR data (ROESY/NOESY and HSQMBC). Cytotoxic, antifungal and antibacterial activities were studied for all isolated compounds. Comparison of the collected data showed crucial importance of 20-membered macrolactone ring for antimicrobial properties of this antibiotic family.Graphical abstractGraphical abstract for this article
       
  • Transition-metal-free sp3 C-H Activation of 2-methylquinoline with
           Terminal Alkynes for Synthesis of 3-(quinolin-2-yl)isoxazoles
    • Abstract: Publication date: Available online 29 April 2019Source: Tetrahedron LettersAuthor(s): Lei Meng, Shuwei Zhang, Xiaodong Jia, Liangzhong Lv, Yu YuanGraphical abstractGraphical abstract for this article
       
  • Synthesis of unsymmetrical 2-(2-vinyl-4H-chromen-4-ylidene)malononitrile
           dyes via Knoevenagel reaction
    • Abstract: Publication date: Available online 29 April 2019Source: Tetrahedron LettersAuthor(s): K.S. Levchenko, K.A. Chudov, E.V. Zinoviev, K.A. Lyssenko, A.N. Fakhrutdinov, D.U. Demin, N.O. Poroshin, P.S. Shmelin, E.P. Grebennikov A series of new chromophores based on 4-(dicyanomethylene)-2-vinyl 4H-chromenes was synthesized and their physical properties (UV–Vis, NMR, mass spectrometry) were studied. The chromophores show moderate or good solubility in organic solvents. Solvatochromism was investigated for compounds in solvents of low (1.4-dioxane, chlorobenzene, methylene chloride) and high polarity (acetone, acetonitrile). The calculations of the first hyperpolarizability (β) was performed using M052X/6-31 + G(d) approximation. Chromophore’s molecules are characterized by high calculated values of the first hyperpolarizability (β) that is only 15% lower than that of FTC analogs.Graphical abstractGraphical abstract for this article
       
  • An unorthodox hydroxymethylation of MEM-protected glucals
    • Abstract: Publication date: Available online 29 April 2019Source: Tetrahedron LettersAuthor(s): Felix Bächle, Alexander Klaiber, Thomas Ziegler During the preparation of 1-tributylstannyl glucals from 1-phenylsulfinyl glycosides an unexpected side reaction was observed for 2,3,4,6-tetra-O-methoxyethoxy (MEM) protected 1-phenylsulfinyl glucoside. Treatment of the latter with lithium diisopropylamide (LDA) afforded the expected, fully MEM protected 1-phenylsulfinyl glucal accompanied by variable amounts of an unexpected 1-phenylsulfinyl 2-hydroxymethyl-3,4,6-tri-O-methoxyethoxyglucal. The amount of the side product rose with increasing concentration of the starting material.Graphical abstractGraphical abstract for this article
       
  • Ru(II)-catalyzed Regioselective C-7 Hydroxymethylation of Indolines with
           Formaldehyde
    • Abstract: Publication date: Available online 29 April 2019Source: Tetrahedron LettersAuthor(s): Yanni Chen, Shili Wan, Yunxiang Wu, Yaxi Yang, Bing Zhou A regioselective addition of C7−H bonds of indolines to formaldehyde is reported to synthesize a variety of C-7 hydroxymethylated indolines via a Ru (II)-catalyzed C-H activation. More importantly, a one-pot C−H formylation procedure is also developed to synthesize valuable C7-formyl indoles.Graphical abstractGraphical abstract for this article
       
  • First total synthesis of the β-carboline alkaloids Trigonostemine A,
           Trigonostemine B and a new synthesis of Pityriacitrin and Hyrtiosulawesine
           
    • Abstract: Publication date: Available online 29 April 2019Source: Tetrahedron LettersAuthor(s): Tímea Szabó, Viktor Hazai, Balázs Volk, Gyula Simig, Mátyás Milen The total synthesis of four natural products, trigonostemine A, trigonostemine B, pityriacitrin, and hyrtiosulawesine was accomplished. The key intermediates, variously substituted 1-formyl-β-carbolines, were prepared in five steps via a novel synthetic approach using readily available starting materials. These formyl derivatives were then further transformed, providing a general route for the synthesis of the four title alkaloids. The method reported herein represents the first total synthesis of the two trigonostemines and a new pathway to pityriacitrin and hyrtiosulawesine.Graphical abstractGraphical abstract for this article
       
  • BODIPY based fluorescent turn-on sensor for highly selective detection of
           HNO and the application in living cells
    • Abstract: Publication date: Available online 29 April 2019Source: Tetrahedron LettersAuthor(s): Xiaolong Zhao, Chao Gao, Na Li, Fayu Liu, Shuhui Huo, Jianzhen Li, Xiaolin Guan, Na Yan On the basis of BODIPY platform, a terpyridyl-substituent BODIPY-Copper complex (Cu(II)-BTPY) was rationally designed and synthesized as a redox reaction fluorescent sensor for detecting HNO over reactive oxygen species (ROS) and reactive nitrogen species (RNS) with impressive selectivity in living cells under mild and neutral conditions. The BTPY exhibits relatively high fluorescence quantum efficiency as much as 34.8% and presents large stokes shift, about 62 nm. When a series of transition metal ions were exploited to investigate the fluorescence quench towards BTPY, copper ion (Cu2+) gave the optimal result. After the fluorescence of the probe being effectively quenched in the presence of Cu2+, it can be in turn recovered through the reduction of Cu2+ into Cu+ by HNO accompanying with a visually observable fluorescence response. Still, the sensing mechanism was evidently confirmed by EPR and ESI-MS measurement. In addition, the employment of BTPY for imaging dyes was also presented in vivo.Graphical abstractA Cu(II)-BODIPY was rationally designed and synthesized as a reducing reaction turn-on fluorescent probe for HNO over ROS and RNS species.Graphical abstract for this article
       
  • Catalytic oxidative conversion of aldehydes into nitriles using
           NH3•H2O/FeCl2/NaI/Na2S2O8: a practical approach to febuxostat
    • Abstract: Publication date: Available online 27 April 2019Source: Tetrahedron LettersAuthor(s): Han Chen, Sijia Sun, Haoying Xi, Kaifang Hu, Ning Zhang, Jingping Qu, Yuhan Zhou A novel approach to convert aldehydes into nitriles using NH3•H2O/FeCl2/NaI/Na2S2O8 has been developed. Both alkyl and aryl nitriles were obtained in good to excellent yields. Electron-withdrawing and electron-donating groups, such as fluoro, chloro, bromo, nitro, ester, cyano, trifluoromethyl and alkoxy were tolerated. Notably, febuxostat and its intermediate, ethyl 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methyl-5-thiazolecarboxylate, were obtained in excellent yields.Graphical abstractGraphical abstract for this article
       
  • Ag2CO3-mediated direct functionalization of alkyl nitriles: facile
           synthesis of γ-ketonitriles through nitrile alkylation of enol acetates
    • Abstract: Publication date: Available online 26 April 2019Source: Tetrahedron LettersAuthor(s): Pi Cheng, Wei Wang, Lin Wang, Jianguo Zeng, Oliver Reiser, Yun Liang Direct C(sp3)-H functionalization of alkyl nitriles is a low toxic and facile route to nitrile-containing compounds. In this research, the Ag2CO3-mediated nitrile methylenation of enol acetates is developed to prepare γ-ketonitriles through the direct C(sp3)-H oxidative functionalization of acetonitrile. A radical pathway is proposed, and acetonitrile serves both as solvent and CN-containing radical source.Graphical abstractGraphical abstract for this article
       
  • Organozinc-aided, HMPA-free, stoichiometric three-component coupling for
           the general synthesis of prostaglandins and stable prostacyclin analogs
           with biological significance
    • Abstract: Publication date: Available online 25 April 2019Source: Tetrahedron LettersAuthor(s): Hiroko Koyama, Atsuto Izumiseki, Masaaki Suzuki A three-component coupling procedure was developed to construct the entire prostaglandin (PG) skeleton under HMPA-free and stoichiometric conditions via a combination of dimethylzinc-aided conjugate addition of an ω-side-chain vinyllithium with (R)-4-hydroxy-2-cyclopentenone and the direct trapping of the resulting enolate with an α-side-chain propargyl triflate. Dimethylzinc effectively regulated both the conjugate addition and alkynylation reactions. Thus, the method afforded protected 5,6-didehydro-PGE2, a common intermediate for the general synthesis of natural PGs and the stable artificial prostacyclin (PGI2) analog isocarbacyclin in 88% yield. The utility of the method was further applied to the syntheses of novel intermediates, which are useful for the straightforward synthesis of 15R-TIC and 15-deoxy-TIC in 79% and 86% yield, respectively.Graphical abstractGraphical abstract for this article
       
  • Development of a water-soluble 3-formylBODIPY dye for fluorogenic sensing
           and cell imaging of sulfur dioxide derivatives
    • Abstract: Publication date: Available online 25 April 2019Source: Tetrahedron LettersAuthor(s): Murat Işık, Ilke Simsek Turan, Suay Dartar A new water-soluble, highly fluorogenic 3-formylBODIPY dye that enables the sensing of SO2 derivatives in aqueous buffers and cancer cells is reported. The quaternary ammonium group appended through the meso-position of the BODIPY dye ensures water solubility. The probe exhibits high specificity for cytosolic (bi)sulfites and fluoresces brightly in human lung adenocarcinoma cells (A549).Graphical abstractGraphical abstract for this article
       
  • NH4I-Promoted N-acylation of amines via the transamidation of DMF and DMA
           under metal-free conditions
    • Abstract: Publication date: Available online 25 April 2019Source: Tetrahedron LettersAuthor(s): Jiahui Chen, Jing Jia, Ziyi Guo, Jitan Zhang, Meihua Xie An unprecedented NH4I-promoted N-formylation and N-acetylization of various amines with dimethylformamide (DMF) and dimethylacetamide (DMA) has been developed. This protocol shows broad substrate scope for aromatic, aliphatic, and heterocyclic amines, which provides a metal-free strategy for N-acylation featuring mild reaction conditions, as well as inexpensive and readily available starting materials.Graphical abstractGraphical abstract for this article
       
  • Synthesis and characterization of (R)-miniPEG-containing chiral γ-peptide
           nucleic acids using the Fmoc strategy
    • Abstract: Publication date: Available online 25 April 2019Source: Tetrahedron LettersAuthor(s): Bo Dong, Kaixuan Nie, Huanhuan Shi, Xiaoxia Yao, Lemeng Chao, Bo Liang, Zhengchun Liu Diethylene glycol (miniPEG)-containing chiral γPNA is considered to be one of the best PNA derivatives. Its preparation is mainly based on the Boc strategy for solid phase peptide synthesis (SPPS), requiring the repeated use of trifluoroacetic acid TFA, which is not suitable for the in situ synthesis of PNA arrays and some other applications under mild conditions. Herein, Fmoc/Cbz orthogonal protected miniPEG-containing chiral γPNA monomers were synthesized, and a 15mer γPNA was prepared using the Fmoc strategy under mild conditions.Graphical abstractGraphical abstract for this article
       
  • H+bond+functionalization+of+N-allylbenzamide+for+CN+and+CC+bond+formation&rft.title=Tetrahedron+Letters&rft.issn=0040-4039&rft.date=&rft.volume=">Copper-catalyzed oxidative CH bond functionalization of N-allylbenzamide
           for CN and CC bond formation
    • Abstract: Publication date: Available online 25 April 2019Source: Tetrahedron LettersAuthor(s): Ranjith Jala, Radha Krishna Palakodety CH bond functionalization for CN and CC bond formations via cross-dehydrogenative coupling (CDC) of N-allylbenzamides with indole as amine source has been developed under a copper-catalyzed condition. To the best of our knowledge, these are the first examples in which different classes of N-containing compounds were directly prepared from the readily available N-allylbenzamides using an inexpensive catalyst-oxidant (CuSO4/TBHP) system. Further, it was applied for the synthesis of α-substituted N-allylbenzamides by using Grignard reagent as nucleophiles.Graphical abstractGraphical abstract for this article
       
  • Synthesis of elaiolide and halichoblelide aglycone
    • Abstract: Publication date: Available online 23 April 2019Source: Tetrahedron LettersAuthor(s): Gregory W. O'Neil, Andrew J. Phillips A synthesis of two structurally related macrodiolides representing the aglycone of natural products elaiophylin and halichoblelide is described. The key transformation for both is a Ti(II)-mediated (silyloxy)enyne cyclization, generating a new methyl stereocenter and providing a diene that can be selectively cross metathesized with crotonic acid.Graphical abstractGraphical abstract for this article
       
  • Synthesis of 3-Aminoindan-1-one Derivatives from 2-Acetylbenzaldehydes and
           Secondary Amines by Mannich Annulation
    • Abstract: Publication date: Available online 23 April 2019Source: Tetrahedron LettersAuthor(s): Yong Zhang, Yonghai Liu, Shuai Zhang, Lei Shi, Wei Wang, Hao Li An acid-promoted 2-component Mannich annulation reaction of readily available acetylbenzaldehydes and secondary amines has been reported. The approach provides a simple and efficient method under mild conditions to synthesize 3-aminoindan-1-one derivatives in moderate to good yields.Graphical abstractGraphical abstract for this article
       
  • Synthesis of 2-Phenyl-1,3-di(4-pyridyl)naphthvalene by Photoinduced
           
    • Abstract: Publication date: Available online 23 April 2019Source: Tetrahedron LettersAuthor(s): Feng Li, Shouliang Zhang, Haijun Hao, Dongyue Chen, Junpeng Zhuang 2-Phenyl-1,3-di(4-pyridyl)naphthvalene 3a was synthesized by the photoinduced reversible valence isomerization of 2-phenyl-1,3-di(4-pyridyl)naphthalene 2a. Then, 3a was converted into 3-phenyl-1,2-di(4-pyridyl)naphthalene 4a and 2a simultaneously. The t1/2 of 3a in DMSO-d6 at 90 °C was 2 h, while that at 110 °C was approximately 10 min.Graphical abstractGraphical abstract for this article
       
  • Copper(I)-Promoted Trifluoromethylthiolation of Arenediazonium salts with
           AgSCF3
    • Abstract: Publication date: Available online 18 April 2019Source: Tetrahedron LettersAuthor(s): Changge Zheng, Yang Liu, Jianquan Hong, Shuai Huang, Wei Zhang, Yupeng Yang, Ge Fang An efficient method for trifluoromethylthiolation of arenediazonium salts has been developed in mild conditions with a stable and convenient AgSCF3. It provides a straightforward and convenient way for the synthesis of trifluoromethylthiolated compound from diazonium salts in moderate to good yields.Graphical abstractGraphical abstract for this article
       
  • Highly Regioselective Synthesis of
           7-Oxo-7H-[1,3,4]thiadiazolo[3,2-a]pyrimidine-5-carboxylate Derivatives
           under Mild Conditions
    • Abstract: Publication date: Available online 11 April 2019Source: Tetrahedron LettersAuthor(s): Hongru Dong, Yuming Zhao 7-Oxo-7H-[1,3,4]thiadiazolo[3,2-a]pyrimidine-5-carboxylate derivatives are biologically and pharmacologically useful heterocycles. An efficient synthetic methodology for this class of compounds was developed through catalyst-free, one-pot reactions between 2-aminothiadiazoles and dimethyl acetylenedicarboxylate (DMAD) in THF with the aid of ultrasound irradiation. The reactions show applicability to a wide range of substrates and high regioselectivity for the “7-one” products over their “5-one” isomers. Detailed reaction mechanisms were mapped out by theoretical modeling analysis based on density functional theory (DFT) calculations. Mechanistic studies indicate that the favored reaction pathway involves a sequence of hydrogen-bond directed Michael addition, synergistic proton transfer/five-membered ring opening, and intramolecular cyano hetero-Diels-Alder reactions.Graphical abstractGraphical abstract for this article
       
 
 
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