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Tetrahedron Letters
Journal Prestige (SJR): 0.683
Citation Impact (citeScore): 2
Number of Followers: 121  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0040-4039 - ISSN (Online) 1359-8562
Published by Elsevier Homepage  [3161 journals]
  • Graphical abstract TOC
    • Abstract: Publication date: 17 October 2018Source: Tetrahedron Letters, Volume 59, Issue 42Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 17 October 2018Source: Tetrahedron Letters, Volume 59, Issue 42Author(s):
       
  • Graphical abstract TOC cont’d
    • Abstract: Publication date: 17 October 2018Source: Tetrahedron Letters, Volume 59, Issue 42Author(s):
       
  • A water-soluble, small molecular fluorescence probe based on
           2-(2’-hydroxyphenyl) benzoxazole for Zn2+ in plants
    • Abstract: Publication date: Available online 24 September 2018Source: Tetrahedron LettersAuthor(s): Yuting Shang, Shuwen Zheng, Madalitso Tsakama, Miao Wang, Weihua ChenA water-soluble, small molecular zinc fluorescence probe (ZFP) based on 2-(2’-hydroxyphenyl) benzoxazole was prepared. It exhibited high selectivity and sensitivity to Zn2+ than the other metal ions. The highest fluorescence enhancement was observed in the presence of Zn2+ owing to the inhibition of excited-state intramolecular proton transfer (ESIPT). Furthermore, fluorescence imaging experiments confirmed that ZFP can be used to monitor Zn2+ in biological systems.Graphical abstractGraphical abstract for this article
       
  • Synthesis of tetraarylmethanes via a Friedel-Crafts
           cyclization/desulfurization strategy
    • Abstract: Publication date: Available online 22 September 2018Source: Tetrahedron LettersAuthor(s): Paul J. Griffin, Matthew A. Fava, St. John T. Whittaker, Kristopher J. Kolonko, Arthur J. CatinoTetraarylmethanes are an important class of molecules that contain four aryl groups bonded to a central carbon atom. The shape/three-dimensionality of these molecules makes them suitable for organic light-emitting diodes (OLEDs), organic solar cells, hydrogen storage, and even drug-delivery. Despite their importance, there are only a few methods available for their preparation. Herein, we report a simple procedure for the preparation of tetraarylmethanes that involves a bismuth-catalyzed Friedel-Crafts cyclization followed by a desulfurization reaction mediated by Raney nickel.Graphical abstractGraphical abstract for this article
       
  • Unsaturated Four-Membered N-Heterocycles: From Synthesis to
           Applications
    • Abstract: Publication date: Available online 22 September 2018Source: Tetrahedron LettersAuthor(s): Dorian Didier, Andreas N. Baumann, Michael EisoldThe ubiquity of strained motifs in drug discovery has recently witnessed a large regain of interest, as such scaffold can be used to modulate the properties of drug candidates. Unsaturated N-containing four-membered heterocycles present unique opportunities to access functionalized azetidines, which play an essential role in pharmacological studies. Even though those unsaturated patterns have been much less reported than the corresponding saturated versions, the consequent impact that those structures could have on molecular design with implementation of strained modules deserves to be summarized. In this review, synthetic accesses to substituted azetes, 1-azetines and 2-azetines are depicted, as well as their involvement in further transformations.Graphical abstractGraphical abstract for this article
       
  • Facile C–H Arylation using Catalytically Active Terminal Sulfurs of 2
           Dimensional Molybdenum Disulfide
    • Abstract: Publication date: Available online 21 September 2018Source: Tetrahedron LettersAuthor(s): Eunhee Hwang, Sae Mi Lee, Sora Bak, Hee Min Hwang, Hyunjung Kim, Hyoyoung LeeThe first methodology of C-H arylation of heteroarene via 2D transition metal dichalcogenides that have catalytically active edge functional groups was described. The terminal sulfur groups could effectively catalyze a formation of an azo-linked intermediate with aryl diazonium salts, leading to produce heteroarenes with good yields.This novel methodology using bulk 2D transition metal dichalcogenides that have catalytically active edge functional groups can apply for various reactions to achieve C-C bond formation in the fields of heterogeneous catalysis that is easily separable, highly reusable, and inexpensive method.Graphical abstractGraphical abstract for this article
       
  • Gold(0) Catalyzed Dehydrogenation of N-Heterocycles
    • Abstract: Publication date: Available online 21 September 2018Source: Tetrahedron LettersAuthor(s): Kumaran Elumalai, Weng Kee LeongGold nanoclusters are good catalyst precursors for the catalytic dehydrogenation of indolines, tetrahydroquinazolines, and related N-heterocycles. The catalytically active species is presumably Au(0) nanoparticles.Graphical abstractGraphical abstract for this article
       
  • Hydrogen Bonding Network Assisted Regio- and Stereo- Controlled
           Hydrohalogenations of Sulfonyl Alkynes
    • Abstract: Publication date: Available online 21 September 2018Source: Tetrahedron LettersAuthor(s): Bocheng Chen, Xiaowen Xia, Xiaojun Zeng, Bo XuWe have developed an efficient synthesis of β-halo Z-sulfonyl alkenes via hydrohalogenations of readily available sulfonyl alkynes. The high hydrogen bonding acidity of linear acetic acid network or aggregate may play a vital role in activation of sulfonyl alkyne substrates. Our condition offers high stereoselectivity, good chemical yields, and high functional group tolerance.Graphical abstractGraphical abstract for this article
       
  • Oxopiperazine capping: formation of oxopiperazine-containing peptoids via
           C-terminal cyclization
    • Abstract: Publication date: Available online 20 September 2018Source: Tetrahedron LettersAuthor(s): Yunjee Lee, Jiwon SeoAn unexpected side reaction was observed in peptoids containing a C-terminal carboxamide with a 2-aminoethyl side chain. The reaction proceeded via cyclization and release of NH3, resulting in C-terminal oxopiperazine formation, analogous to pyroglutamate formation from N-terminal glutamine in peptides. Reaction conditions that promote oxopiperazine formation were developed. In particular, the addition of organic bases accelerated the cyclization, thus providing a simple strategy for the post-synthetic C-terminal capping of peptoids.Graphical abstractGraphical abstract for this article
       
  • Colorimetric detection of histidine in aqueous solution by Ni2+ complex of
           a thiazolylazo dye based on indicator displacement mechanism
    • Abstract: Publication date: Available online 20 September 2018Source: Tetrahedron LettersAuthor(s): Tatsuya Nagae, Shunichi Aikawa, Koshiro Inoue, Yasumasa FukushimaA colorimetric naked-eye chemosensor for histidine (His) was established by mixing a thiazolylazo dye and Ni2+ in a 1:1 molar ratio (TAMSMB-Ni2+). Due to the interaction of Ni2+ with His, TAMSMB was regenerated upon the addition of His to TAMSMB-Ni2+ to lead a significant hypsochromic shift in absorption spectra accompanied by a visual color change from red to yellow which can be directly observed by the naked eye. On the other hands, other amino acids did not trigger any significant changes in absorption properties and solution color. Moreover, it exhibited the selective recognition of His without obvious interference from other amino acids. Thus, TAMSMB-Ni2+ can act as a simple and efficient colorimetric chemosensor for His with sensitivity and selectivity in aqueous solution.Graphical abstractGraphical abstract for this article
       
  • Efficient sulfonylation of ketones with sodium sulfinates for the
           synthesis of β-keto sulfones
    • Abstract: Publication date: Available online 20 September 2018Source: Tetrahedron LettersAuthor(s): Siqi Deng, En Liang, Yinrong Wu, Xiaodong TangThe oxidative sulfonylation of ketones with sodium sulfinates as the sulfone source and DMSO as the oxidant is reported. A series of β-keto sulfones were obtained in good to excellent yields. The advantages of this efficient protocol include the low cost of DMSO and HBr, and a broad scope.Graphical abstractGraphical abstract for this article
       
  • Ag-catalyzed Sulfonylation-Peroxidation of Alkenes with Sulfonyl
           hydrazides and T-Hydro
    • Abstract: Publication date: Available online 20 September 2018Source: Tetrahedron LettersAuthor(s): Ran Xu, Zhiping LiThe sulfonylation-peroxidation of alkenes with sulfonyl hydrazides and T-hydro was developed. The Ag-catalyzed three-component peroxidation provides a method for synthesis of a variety of β-sulfonyl peroxides, which could be converted into various sulfone derivatives.Graphical abstractGraphical abstract for this article
       
  • Conformational analysis of
           N-aryl-N-(2-azulenyl)acetamides
    • Abstract: Publication date: Available online 20 September 2018Source: Tetrahedron LettersAuthor(s): Ai Ito, Takamasa Amaki, Ayako Ishii, Kazuo Fukuda, Ryu Yamasaki, Iwao OkamotoAromatic amides bearing 2-azulenyl group on the amide nitrogen were synthesized and their structures were investigated. The π-electron density of the N-aryl group was found to influence the cis-trans conformational preferences of these compounds in solution. X-Ray crystallography revealed that the plane of the 2-azulenyl ring has a strong tendency to lie coplanar with the amide plane when the azulene group is located on the same side as the amide oxygen atom.Graphical abstractGraphical abstract for this article
       
  • Synthesis of enantiomerically-enriched N-aryl amino-amides via a
           Jocic-type reaction
    • Abstract: Publication date: Available online 19 September 2018Source: Tetrahedron LettersAuthor(s): Christian Hobson, Michael S. Perryman, Gavin Kirby, Guy J. Clarkson, David J. FoxEnantiomerically-enriched secondary trichloromethyl-alcohols react with aryl amines to give enantiomerically-enriched α-N-arylamino-acid derivatives. The intermediate acid chlorides can react in situ with aryl or, regioselectively, with alkyl amines to give aryl or alkyl α -N-arylamino amides.Graphical abstractGraphical abstract for this article
       
  • Multicomponent synthesis of substituted
           3-styryl-1H-quinoxalin-2-ones in an aqueous medium
    • Abstract: Publication date: Available online 19 September 2018Source: Tetrahedron LettersAuthor(s): Erivaldo P. da Costa, Sara E. Coelho, André H. de Oliveira, Renata M. Araújo, Livia N. Cavalcanti, Josiel B. Domingos, Fabrício G MenezesA multicomponent synthesis of substituted 3-styryl-1H-quinoxalin-2-ones is described. Sequential reactions of o-phenylenediamine with sodium pyruvate and aldehydes in 20% aqueous acetic acid containing sodium acetate provided the target products in good to high yields. The reaction is proposed to proceed via initial condensation of the diamine and pyruvate partners followed by an aldol condensation-type mechanism.Graphical abstractGraphical abstract for this article
       
  • New spiro phosphinooxazolines for palladium-catalyzed asymmetric allylic
           amination
    • Abstract: Publication date: Available online 18 September 2018Source: Tetrahedron LettersAuthor(s): Yanfeng Gao, Zhongxuan Qiu, Rui Sun, Nanxing Gao, Guorui Cao, Dawei TengThe new conformational rigid spiro phosphinooxazolines 1 were synthesized from 7-bromo-1-indanone. The asymmetric catalytic potential of them was demonstrated in the asymmetric palladium catalyzed allylic amination. High yields and enantioselectivities were obtained with alkylamines.Graphical abstractGraphical abstract for this article
       
  • Graphical abstract TOC
    • Abstract: Publication date: 10 October 2018Source: Tetrahedron Letters, Volume 59, Issue 41Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 10 October 2018Source: Tetrahedron Letters, Volume 59, Issue 41Author(s):
       
  • Graphical abstract TOC cont’d
    • Abstract: Publication date: 10 October 2018Source: Tetrahedron Letters, Volume 59, Issue 41Author(s):
       
  • A colorimetric squaraine-based probe and test paper for rapid naked eyes
           detection of copper ion (II)
    • Abstract: Publication date: Available online 18 September 2018Source: Tetrahedron LettersAuthor(s): Yang Liu, Liqiu Wang, Chenxiao Guo, Yajuan HouA colorimetric probe N,N’-bis(2-methoxy-ethyl)-2,3,3-trimethyl-3H-squaraine (MOESQ) with H2O solubility was synthesized to detect Cu2+. MOESQ exhibits good selectivity, high sensitivity and fast UV-Vis response toward Cu2+ over other competing ions in CH3CN. The detection limit of MOESQ for Cu2+ in CH3CN can reach 1.88×10-7 molL-1. By adsorbing MOESQ on the chromatography paper, a colorimetric test paper for Cu2+ was prepared, which could detect Cu2+ with the color change from blue to faint yellow even in the limit of detection concentration of 10-6 molL-1.Graphical abstractA colorimetric sensor MOESQ based on squaraine was synthesized to detect Cu2+ in CH3CN with the detection limit of 1.88×10-7 molL-1. By adsorbing MOESQ on the chromatography paper, a colorimetric test paper for Cu2+ was prepared, which could detect Cu2+ with the color change from blue to faint yellow in the limit of detection concentration of 10-6 molL-1.Graphical abstract for this article
       
  • Multicatalytic Beckmann Rearrangement of 2-Hydroxylarylketone Oxime:
           Switchable Synthesis of Benzo[d]oxazoles and N-(2-Hydroxylaryl)amides
    • Abstract: Publication date: Available online 18 September 2018Source: Tetrahedron LettersAuthor(s): Zhen Li, Chengtao Fang, Yannan Zheng, Guanyinsheng Qiu, Xiaofang Li, Hongwei ZhouA switchable synthesis route is developed for benzo[d]oxazole derivatives and (2-hydroxylaryl)benzamide from 2-hydroxylbenzeneketoxime using organomolecules (BOP-Cl, and CNC) and Lewis acid cocatalyzed Beckmann rearrangement (BR) reaction. Further, this reaction is switched using different organocatalysts.Graphical abstractGraphical abstract for this article
       
  • The investigation on the N-H reactivity of pentacoordinate
           spirophosphoranes by H/D exchange and NMR experiments
    • Abstract: Publication date: Available online 17 September 2018Source: Tetrahedron LettersAuthor(s): Can Sun, Shuxia Cao, Pei Zhao, Wenwen Ma, Yanchun Guo, Yufen ZhaoDifferent pentacoordinate spirophosphoranes were investigated by H/D exchange and NMR tracking experiments. The H/D exchanged site of spirophosphoranes was confirmed to be the N-H bond instead of the P-H bond according to the integration of the signal changes in proton-decoupled, proton-coupled 31P NMR and 1 H NMR tracking experiments. The reactivity of N-H bond at the spiro-ring of spirophosphoranes was explored by the rate constant of H/D exchange of different spirophosphoranes. The results demonstrated that the reactivity of N-H bond of spirophosphoranes was influenced by steric hindrance and the species of substituent at phosphorus atom, and the electronic effect of the substituent was the main effect factor on the reactivity of the N-H bond. The strong electron-withdrawing group at phosphorus resulted in more reactive N-H bond of spirophosphoranes. These results are beneficial to further understand and explore the characteristics of pentacoordinate spirophosphoranes.Graphical abstractGraphical abstract for this article
       
  • Safer Solvents for Reactive Organometallic Reagents
    • Abstract: Publication date: Available online 17 September 2018Source: Tetrahedron LettersAuthor(s): Thomas J. Malinski, David E. BergbreiterThis paper describes the use of poly(α -olefin)s (PAOs) as safer alternatives to cyclohexane, hexanes, and heptane as solvents for alkyllithium reagents. While PAOs like any alkane are flammable, PAOs do not readily catch on fire because they contain 20 or more carbon atoms, a low volatility, and have a high flash point vis-à-vis alkanes like hexane. Also unlike conventional alkanes, PAOs can be quantitatively separated from polar organic solvents and polar organic products either by a simple gravity separation or by an extraction after a reaction. Any leaching of the PAO solvent into a polar phase during such a separation can be minimized by addition of small amounts of water to the polar phase. However, while these PAO solvents have some physical differences from conventional low molecular weight volatile alkanes, they otherwise behave like alkanes and alkyllithium reagents in these PAO solvents can used in their conventional reactions in these PAO solvents.Graphical abstractGraphical abstract for this article
       
  • Resorcinarene Supramolecular Organocatalyst for Functionalized 1-tetralone
           Synthesis in Aqueous Medium
    • Abstract: Publication date: Available online 17 September 2018Source: Tetrahedron LettersAuthor(s): Pampa Maity, Chhanda MukhopadhyayAn efficient, straightforward and environmentally benign process has been developed for the synthesis of fluorenone and 1- tetralone derivatives using cyclic 1,3-dione, malononitrile and dialkylacetylenedicarboxylate as starting materials in aqueous medium. The reaction is favoured in presence of resorcin[4]arene which is effective as a reusable organocatalyst. The catalyst has been easily synthesized and characterized by 1H, 13C NMR, IR, XRD and HRMS analyses. Resorcin[4]arene afforded the resulted products in a shorter time and in good yields. The recyclability of the catalyst was established up to 6th cycle by FT-IR and SEM images.Graphical abstractGraphical abstract for this article
       
  • A new and efficient method for the synthesis of 3-(2-nitrophenyl)pyruvic
           acid derivatives and indoles based on the Reissert reaction
    • Abstract: Publication date: Available online 17 September 2018Source: Tetrahedron LettersAuthor(s): Vakhid A. Mamedov, Vera L. Mamedova, Victor V. Syakaev, Gul'naz Z. Khikmatova, Dmitry E. Korshin, Temur A. Kushatov, Shamil K. LatypovThe formation of 3-(2-nitrophenyl)pyruvic acid and its amide and ester derivatives – key compounds for the Reissert indole synthesis – was achieved under various reaction conditions via the acid catalyzed hydrolysis of 5-(2-nitrobenzyliden)-2,2-dimethyl-1,3-oxazolidin-4-one, which is readily available from 3-(2-nitrophenyl)oxirane-2-carboxamide. A new and highly efficient method for the synthesis of indole-2-carboxylic acid derivatives via the intramolecular reductive cyclization of o-nitrophenylpyruvic acid and its amide and ester derivatives was developed using Na2S2O4 in dioxane/water at reflux.Graphical abstractGraphical abstract for this article
       
  • Ytterbium-catalyzed formal [4+2] cycloaddition: Synthesis of
           chalcogen-quinolines 3-unsubstituted
    • Abstract: Publication date: Available online 15 September 2018Source: Tetrahedron LettersAuthor(s): Isadora M. de Oliveira, Mariana P. Darbem, C. Henrique A. Esteves, Daniel C. Pimenta, Julio Zukerman-Schpector, Hélio A. Stefani, Flávia ManarinA regioselective ytterbium-catalyzed annulation reaction between ethylglyoxalate, anilines and silyl-alkynes bearing selenyl- and telluryl- moieties for the formation of poly-substituted quinolones is described. A series of examples formed under mild conditions are presented, including a scaled-up reaction and a study on catalyst recyclability.Graphical abstractGraphical abstract for this article
       
  • Protected pyrimidine nucleosides for cell-specific metabolic labeling of
           RNA
    • Abstract: Publication date: Available online 15 September 2018Source: Tetrahedron LettersAuthor(s): Samantha Beasley, Kim Nguyen, Michael Fazio, Robert C. SpitaleRNA molecules can perform a myriad of functions, from the regulation of gene expression to providing the genetic blueprint for protein synthesis. Characterizing RNA expression dynamics, in a cell-specific manner, still remains a great challenge in biology. Herein we present a new set of protected alkynyl nucleosides for cell-specific metabolic labeling of RNA. We anticipate these analogs will find wide spread utility toward the goal of understanding RNA expression in complex cellular and tissue environments, even within living animals.Graphical abstractGraphical abstract for this article
       
  • Synthesis of a new pyrene-devived fluorescent probe for the detection of
           Zn2+
    • Abstract: Publication date: Available online 15 September 2018Source: Tetrahedron LettersAuthor(s): Yanfeng Tang, Yang Huang, Linxia Lu, Chun Wang, Tongming Sun, Jinli Zhu, Guohua Zhu, Jinyang Pan, Yingli Jin, Ailin Liu, Miao WangA novel pyrene-based receptor bearing benzothiazole was synthesized as a good turn-on fluorescent sensor for the recognition of Zn2+. The probe showed an excellent selectivity for Zn2+over most other competing ions (eg, Cr3+, Li+, Cd2+, Al3+, Pb2+, Li+, Mg2+, Ag+, Ca2+, Ni2+, Mn2+, Fe3+, Hg2+, Ba2+, K+, Na+, Cu2+, Fe2+) in EtOH-HEPES (65:35, v/v, pH=7.20), which might be attributed to the photoinduced electron transfer (PET) mechanism. The formation of 1:1 stoichiometric PBZ-Zn2+ complex was determined based on the Job's plot, 1H NMR titration and ESI-MS. The binding constant of the complex was 4.04×104 M-1 with a detection limit of 2.58×10-7 M. The potential application of the PBZ in real water samples for recognizing Zn2+ was investigated. Bio-imaging study also revealed that PBZ could be applied to detecting Zn2+ in live cells. These results indicated that PBZ could be a favorable probe for Zn2+.Graphical abstractGraphical abstract for this article
       
  • A mild method for the synthesis of
           bis-pyrazolo[3,4-b:4',3'-e]pyridine derivatives
    • Abstract: Publication date: Available online 14 September 2018Source: Tetrahedron LettersAuthor(s): Rui Qiu, Shujia Qiao, Boyu Peng, Jiajia Long, Guodong YinA mild and efficient method for the synthesis of bispyrazolo[3,4-b:4',3'-e]pyridines from 5-aminopyrazoles and aromatic aldehydes using an inexpensive FeCl3 catalyst is reported. The reaction temperature was reduced from 220–250 oC to 130 oC compared to conventional methods. A large proportion of the products precipitated directly from the mixture at room temperature. Aliphatic and α,β-unsaturated aldehydes selectively resulted in formation of the corresponding 1H-pyrazolo[3,4-b]pyridine derivatives. A possible domino reaction mechanism was also proposed. Several aryl alkynyl groups were introduced to these tricyclic molecules via the Sonogashira coupling reaction.Graphical abstractGraphical abstract for this article
       
  • Co-cross-linking of Bio-based Multi-functional Epoxide and Bisphenol A
           Diglycidyl Ether with 2-Ethyl-4-methylimidazole
    • Abstract: Publication date: Available online 14 September 2018Source: Tetrahedron LettersAuthor(s): Hisatoyo Morinaga, Mayu SakamotoA co-cross-linking reaction of bio-based multi-functional epoxides (1) derived from limonene oxide and bisphenol A diglycidyl ether (BPADE) in the presence of 2-ethyl-4-methylimidazole (EMI) as a cross-linker afforded the corresponding network copolymers (2) having the 10 % thermal decomposition temperature (Td10) of 294.4 °C at maximum. Adhesive strength induced by 1, especially tetra-functional epoxide, and BPADE exhibited remarkably higher than that by BPADE alone.Graphical abstractGraphical abstract for this article
       
  • Naphthalene dianhydride based selective detection targetable fluorescent
           probe for monitoring exogenous Iron in living cells
    • Abstract: Publication date: Available online 14 September 2018Source: Tetrahedron LettersAuthor(s): Gandhaveeti Rohini, Konakanchi Ramaiah, Anandaram SreekanthA green emissive PET operating fluorescent turn-on cell permeable novel probe R1 has been successfully developed and utilized for the detection of Fe+3 in the pure aqueous system at sub-nanomolar level. Moreover, probe R1 demonstrate highly sensitive and selective towards Fe+3 over the other divalent and trivalent metal ions and was established by using fluorescence spectroscopy. The efficiency and aid of R1 was demonstrated by the fluorescence imaging of captured Fe+3 within Pollen grains by using fluorescence microscopy. These results indicate that, this is the first fluorescent turn-on PET probe to detect sub-nanomolar Fe+3 in the pure aqueous system and in cellular level.Graphical abstractGraphical abstract for this article
       
  • Transition metal free large-scale synthesis of aromatic vinyl chlorides
           from aromatic vinyl carboxylic acids using bleach
    • Abstract: Publication date: Available online 14 September 2018Source: Tetrahedron LettersAuthor(s): Navnath T Hatvate, Balaram S. Takale, Shrikant M. Ghodse, Vikas N. TelvekarWhile continuing our research on Hunsdiecker reaction, we came across an interesting application of bleach, sodium hypochlorite (NaOCl) for decarboxylative chlorination reaction. The reaction is easily scaled up to 10 mmol. The reaction has good tolerance towards wide variety of functional groups. The reaction has mild conditions and gave relatively high chemical yield of the desired product.Graphical abstractGraphical abstract for this article
       
  • Formal synthesis of Pellasoren - A
    • Abstract: Publication date: Available online 14 September 2018Source: Tetrahedron LettersAuthor(s): Katta Muralikrishna, Gavireddy Chaithanya kumar, Vavilapalli Satyanarayana, R. Sudheer Kumar, Jhillu singh YadavA convergent and highly stereoselctive formal synthesis of Pellasoren – A is described. The salient features of the synthesis are the utilization of enzymatic desymmetrization, Crimmin’s non-Evans syn aldol, Lindlar’s and Wittig reaction.Graphical abstractGraphical abstract for this article
       
  • Visible Light-Induced 4-Phenylthioxanthone-Catalyzed Aerobic Oxidation of
           Triarylphosphines
    • Abstract: Publication date: Available online 13 September 2018Source: Tetrahedron LettersAuthor(s): Aishun Ding, Shijie Li, Yang Chen, Ruiwen Jin, Cong Ye, Jianhua Hu, Hao GuoWe report herein a visible light-induced oxidation of triarylphosphines under aerobic condition with excellent functional group tolerance. In this transformation, the photo catalyst 4-phenylthioxanthone acted as a photosensitizer for the in situ generation of singlet oxygen. This new approach provided a cheaper and greener method for the preparation of phosphine oxide, showing great advantages in environmental protocols.Graphical abstractGraphical abstract for this article
       
  • Potassium iodide-mediated radical arylsulfonylation/1,2-carbon migration
           sequences for the synthesis of β-sulfonated cyclic ketones
    • Abstract: Publication date: Available online 12 September 2018Source: Tetrahedron LettersAuthor(s): Yeon Joo Kim, Mi Hyeon Choo, Dae Young KimPotassium iodide-mediated radical sulfonylation/1,2-carbon migration sequences of alkenylcyclobutanols has been developed. The reaction was effectively accelerated using potassium iodide as a catalyst under mild reaction conditions without other metal oxidant. This approach is environmentally benign by use of shelf-stable arylsulfonyl hydrazides as arylsulfonyl radical precursor and water as solvent. This approach offers a facile way to prepare β -sulfonated cyclic ketone derivatives.Graphical abstractGraphical abstract for this article
       
  • Influence of the side chain protecting group on the stereoselectivity of
           the 1,3-dipolar cycloaddition of D-talo-configured nitrones
    • Abstract: Publication date: Available online 12 September 2018Source: Tetrahedron LettersAuthor(s): Tomáš Malatinský, Zsófia Puhová, Matej Babjak, Jana Doháňošová, Ján Moncol, Štefan Marchalín, Róbert FischerTwo new five-membered cyclic D-talo-configured nitrones were synthesized from D-mannose, and examined in 1,3-dipolar cycloadditions with vinyl acetate and vinylene carbonate. The stereoselectivity of the cycloadditions depends greatly on the protecting group of the vicinal diol attached to the nitrone C-5 carbon atom. Methyl protection resulted in limited syn/anti-selectivity, giving mixtures of the two isomeric exo-syn and exo-anti isoxazolidines in comparable amounts. On the other hand, the cyclohexylidene-substituted nitrone reacted more selectively in favour of the syn isomer. The difference in the diastereoselectivity was attributed to the specific spatial orientation of the nitrone C-5 substituent.Graphical abstractGraphical abstract for this article
       
  • Synthesis of 6,6-Dimethyltricyclo[5.4.0.02,8]undecane-2,9-diol for
           (ent-)Longipinane-type Sesquiterpenoids Using Two Types of Radical
           Cyclization Reactions
    • Abstract: Publication date: Available online 12 September 2018Source: Tetrahedron LettersAuthor(s): Kazuma Matsunaga, Kazuhiko Takatori, Hiroshi Kogen, Naoki SaitoA synthetic route to 6,6-dimethyltricyclo[5.4.0.02,8]undecane-2,9-diol, a key precursor to (ent-)longipinane-type sesquiterpenoids, is described. This unique core common to (ent-)longipinanes was constructed using two types of intramolecular radical cyclization reactions, namely, intramolecular coupling of an acid chloride and an alkyl iodide mediated by SmI2, TBAI and HMPA, and the coupling of a ketone and an epoxide mediated by Cp2TiI2 and SmI2.Graphical abstractGraphical abstract for this article
       
  • A new method using 1,3,5-triazine as an umpolung hydrogen cyanide
           equivalent toward the syntheses of isoquinolinone and 2-pyridone
           derivatives
    • Abstract: Publication date: Available online 12 September 2018Source: Tetrahedron LettersAuthor(s): Joji Hayashida, Shinya YoshidaAn investigation of Hermecz and Hartenstein’s cyclization methods was conducted. Overcoming the limited substrate scope allowed the expansion of the synthetic application of 1,3,5-triazine as an umpolung hydrogen cyanide equivalent. The reaction proceeded under mild conditions to provide various isoquinolinone and 2-pyridone derivatives with excellent yields.Graphical abstractGraphical abstract for this article
       
  • Selective recognition and electrochemical sensing of dopamine using a
           ferrocene-based heteroditopic receptor
    • Abstract: Publication date: Available online 11 September 2018Source: Tetrahedron LettersAuthor(s): Hidekazu Miyaji, Haruka Komada, Keisuke Goto, Junko Fujimoto, Naoaki Kiriyama, James H.R. TuckerA redox-active ferrocene-based heteroditopic receptor bearing a boronic acid (as a catechol recognition site) and a benzo-18-crown-6-ether unit (as an ammonium ion recognition site) was synthesized. A 1:1 ditopic complex with dopamine was evidenced by mass spectrometry and NMR spectroscopy. Cyclic voltammetry measurements on the receptor in the presence of a series of organic guest species demonstrated the successful electrochemical sensing of dopamine through a distinct change in the ferrocene-centred redox-couple upon complex formation.Graphical abstractGraphical abstract for this article
       
  • Site-Selective C−H Nitration of N-Aryl-7-Azaindoles Under
           Palladium(II) Catalysis
    • Abstract: Publication date: Available online 11 September 2018Source: Tetrahedron LettersAuthor(s): Rina Chun, Saegun Kim, Sang Hoon Han, Ashok Kumar Pandey, Neeraj Kumar Mishra, In Su KimThe site-selective C–H nitration reaction of 7-azaindoles with t-butyl nitrite under palladium catalysis is described. This protocol provides an efficient method for the construction of ortho-nitrated N-aryl-7-azaindoles with excellent site-selectivity and functional group compatibility. The formed 7-azaindole derivatives can be readily transformed into 7-azaindoles containing an aniline functional group under palladium-catalyzed hydrogenation conditions.Graphical abstractGraphical abstract for this article
       
  • One-pot synthesis of dihydroquinazolinethione-based polycyclic system
    • Abstract: Publication date: Available online 10 September 2018Source: Tetrahedron LettersAuthor(s): Wensheng Zhang, Xiaofeng Zhang, Xiaoming Ma, Wei ZhangA one-pot and diastereoselective synthesis of quinazoline-2(1H)-thione-containing polycyclic compounds is introduced. The reaction process includes [3+2] cycloaddition of azomethine ylides for pyrrolidines, Staudinger-aza-Wittig reaction of azides for iminophosphoranes, formation of isothiocyanates, and finally cyclization of amines to isothiocyanates for dihydroquinazolinethiones.Graphical abstractGraphical abstract for this article
       
  • Single chemosensor for sensing multiple analytes: selective fluorogenic
           detection of Cu2+ and Br–
    • Abstract: Publication date: Available online 10 September 2018Source: Tetrahedron LettersAuthor(s): Yoon Gun Ko, Mayank, Narinder Singh, Doo Ok JangA tripodal receptor R1 with a combination of nitrogen and oxygen-based binding sites was designed and used for the selective determination of Cu2+. The fluorescence emission profile of R1 in the presence of Cu2+ showed a marked enhancement in fluorescence intensity, indicating high selectivity among other metal ions. The R1–Cu2+ complex was further explored as a sensor for anion detection. Upon addition of Br–, switching to a fluorescence “off” state was observed. The Br– selectivity of the complex over a wide range of concentrations was observed via titrimetric analysis through changes in the emission spectra.Graphical abstractGraphical abstract for this article
       
  • Synthesis of 8-deoxypumiliotoxin 193H and 9-deoxyhomopumiliotoxin 207O
    • Abstract: Publication date: Available online 8 September 2018Source: Tetrahedron LettersAuthor(s): Takuya Okada, Taiga Yamamoto, Daiki Kato, Masashi Kawasaki, Ralph A. Saporito, Naoki ToyookaThe asymmetric synthesis of 8-deoxypumiliotoxin 193H and 9-deoxyhomopumiliotoxin 207O has been achieved, starting from both enantiomers of (+)- and (-)-10. Enantiomerically pure alcohols (+)- and (-)-10 were obtained by lipase-mediated kinetic resolution of racemic 10, which was prepared in 3 steps from new lactam-type building block (-)-8 in a highly stereoselective manner.Graphical abstractGraphical abstract for this article
       
  • Mn/Cu catalyzed addition of arylboronic acid to nitriles: Direct synthesis
           of arylketones
    • Abstract: Publication date: Available online 8 September 2018Source: Tetrahedron LettersAuthor(s): Dina Moustafa, Chelsea Sweet, Hyun Lim, Brenda Calalpa, Parminder KaurA direct and efficient synthesis of arylketones via arylboronic acid addition to nitriles in presence of inexpensive Mn/Cu catalytic system is reported. The use of non-precious Mn and Cu salts has been found to be highly advantageous both in terms of accessibility as well as cost effectiveness. A series of arylboronic acids as well as nitriles were used to synthesize a variety of symmetrical and unsymmetrical arylketones. Based on the literature studies, the reaction mechanism is anticipated to go through an aryl radical intermediate which reacted with the copper activated nitrile to give the desired arylketones after the hydrolysis of the imine intermediate.Graphical abstractGraphical abstract for this article
       
  • Selective carboxylation of substituted phenols with engineered
           Escherichia coli whole-cells
    • Abstract: Publication date: Available online 8 September 2018Source: Tetrahedron LettersAuthor(s): Chang Peng, Yuxue Liu, Xiaojia Guo, Wujun Liu, Qing Li, Zongbao K. ZhaoSelective carboxylation of substituted phenols is realized in the presence of bicarbonate under ambient pressure by engineered Escherichia coli whole-cells expressing various hydroxybenzoate decarboxylases, leading to their corresponding ortho-hydroxybenzoates. This process may be further developed as an efficient route to upgrade lignin-derived phenolic compounds as valuable building blocks.Graphical abstractGraphical abstract for this article
       
  • One-pot, microwave-assisted synthesis of polymethylene-bridged
           bis(1H-1,2,4-triazol-5(3)-amines) and their tautomerism
    • Abstract: Publication date: Available online 8 September 2018Source: Tetrahedron LettersAuthor(s): Felicia Phei Lin Lim, Lee Ming Hu, Edward R.T. Tiekink, Anton V. DolzhenkoA highly selective and efficient method for the synthesis of 3,3’(5,5’)-polymethylene-bis(1H-1,2,4-triazol-5(3)-amines) was developed using the reaction of dicarboxylic acids and aminoguanidine in an aqueous medium. This one-pot, microwave-promoted method was proved to be scalable affording the desired products in good yields and purity. The scope of the method was successfully explored by the preparation of a small library of polymethylene-bis(1H-1,2,4-triazol-5(3)-amines) with different alkyl chain linkers. The annular prototropic tautomerism in the prepared compounds was studied using NMR spectroscopy and X-ray crystallography.Graphical abstractGraphical abstract for this article
       
  • Synthesis and photophysical characterization of heterocyclic
           dihydrotetracenes and their utility in the fluorescence imaging of HeLa
           cells
    • Abstract: Publication date: Available online 7 September 2018Source: Tetrahedron LettersAuthor(s): Subhadeep Banerjee, Apeksha Ashok Phadte, Anjan Chattopadhyay, Joseph R.D. Fernandes, Akanksha Vinod Savardekar, Arnab Banerjee, Keisham Sarjit SinghAza- and oxa-dihydrotetracenes were prepared in one step from 1,4-dicyanodibenzodioxins in good yields. These molecules represent the first examples of heterocyclic dihydrotetracenes with push-pull character. Aza-dihydrotetracene 18H showed a strong red-shifted absorbance maxima at 472 nm, nearly equal in intensity to the parent band at 260 nm, in polar DMSO medium. The fluorescence emission spectrum of aza-dihydrotetracene 18H had an emission maximum at 525 nm with a broad band stretched out as far as 650 nm. The fluorescence emission quantum yield was almost as strong as the known fluorescent standard 1,3-diphenylisobenzofuran. The aza–dihydrotetracenes exhibited in vitro cytotoxicity against the HeLa cell line and were non-toxic against the normal HaCaT cell line. The fluorescence emerging from HeLa cells incubated with aza-dihydrotetracene 18H was very strong and helped detect the cells microscopically using appropriate filters.Graphical abstractGraphical abstract for this article
       
  • Synthesis of 1-Hydrocarbon Substituted Cyclopropyl Silyl Ketones
    • Abstract: Publication date: Available online 7 September 2018Source: Tetrahedron LettersAuthor(s): Mitsunori Honda, Sho Sasaki, Tsuyoshi Nishimoto, Hiromoto Koshiro, Ko-Ki Kunimoto, Masahito SegiThe synthesis of cyclopropyl silyl ketones possessing a hydrocarbon group at 1-position of three-membered ring was investigated. The reaction of sulfoxonium ylide with α,β unsaturated acylsilanes derived from α,β unsaturated aldehydes did not afford the desired acylsilane derivatives. Instead, the corresponding silyl enol ethers were yielded exclusively. On the other hand, the Corey-Chaykovsky cyclopropanation of α -substituted α,β unsaturated aldehydes proceeded well to give 1-substituted cyclopropyl aldehydes. The silyl substitution of formyl proton in the obtained aldehydes via umpolung of carbonyl group afforded the target acylsilanes.Graphical abstractGraphical abstract for this article
       
  • Fluoranthene and its π-extended diimides: Construction of new
           electron acceptors
    • Abstract: Publication date: Available online 7 September 2018Source: Tetrahedron LettersAuthor(s): Hiroyuki Ishikawa, Koji Katayama, Jun-ichi Nishida, Chitoshi Kitamura, Takeshi Kawase3,4,8,9-Fluoranthenetetracarboxylic diimides (FDI) are first synthesized as stable yellow compounds by the Diels-Alder (DA) reaction of maleic anhydride and acecyclone derivative bearing an acenaphthylene imide unit and subsequent imidations. An X-ray crystallographic analysis of di(N-octyl)FDI derivative reveals the planar fluoranthene diimide π -system. The cyclic voltammograms of FDIs shows considerably high electron affinity. Moreover, its π -extended analogue involving an anthracene unit (DAAI) was also prepared by the DA reaction of acenaphthylene-3,4-dicarboxylic imide with o-xylylene derivative. The compound exhibits long wavelength absorption and intense fluorescence with moderate solvatofluorochromism (ΔλEM = 41 nm). Theoretical calculations based on density function theory (DFT) were performed to characterize the electronic feature of these diimides.Graphical abstractGraphical abstract for this article
       
  • Bismuth-Catalyzed Synthesis of 2-Substituted Quinazolinones
    • Abstract: Publication date: Available online 7 September 2018Source: Tetrahedron LettersAuthor(s): Sandeep R. Vemula, Dinesh Kumar, Gregory R. CookThe bismuth-catalyzed oxidative condensation of aldehydes with 2-aminobenzamide under aerobic conditions is reported using ethanol as the solvent. Good to excellent isolated yields (68-95%) of the corresponding 2-substituted quinazolinones were obtained under mild reaction conditions with excellent functional group tolerance. The quinazolinones were further functionalized to afford N-allylated quinazolinones, 2-aminopyridine derivatives, and annulated polyheterocyclic compounds via transition-metal catalyzed reactions.Graphical abstractGraphical abstract for this article
       
  • Croissamide, a proline-rich cyclic peptide with an N-prenylated tryptophan
           from a marine cyanobacterium Symploca sp.
    • Abstract: Publication date: Available online 7 September 2018Source: Tetrahedron LettersAuthor(s): Keitaro Iwasaki, Arihiro Iwasaki, Shimpei Sumimoto, Takuya Sano, Yuki Hitomi, Osamu Ohno, Kiyotake SuenagaCroissamide, a proline-rich cyclic peptide that contains an N-prenylated tryptophan, was isolated from a marine cyanobacterium Symploca sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on chiral HPLC analyses of acid hydrolysates.Graphical abstractGraphical abstract for this article
       
  • Metal-Free TBAI-Catalyzed Oxidative Csp 3-S Bond Formation through
           Csp 2-Csp 2 Bond and S-N Bond Cleavage: A New Route to β-keto-Sulfones
    • Abstract: Publication date: Available online 6 September 2018Source: Tetrahedron LettersAuthor(s): Yucai Tang, Ying Chen, Hui Liu, Min GuoA novel TBAI-catalyzed radical sulfonylation of readily available N,N-dimethylenaminones with sulfonylhydrazides to afford functionalized β-keto-sulfones has been developed. Various functional groups were tolerated well under the present oxidative conditions and the corresponding β-keto-sulfone compounds were obtained in moderate to good yields. Importantly, this transformation offered the first protocol for Csp3-S bond formation by oxidative Csp2-Csp2 bond cleavage in one step.Graphical abstractGraphical abstract for this article
       
  • A mild capping method for SPPS on the N-methyl diaminobenzoyl linker:
           synthesis of an N-acyl urea appended C. elegans neuropeptide
    • Abstract: Publication date: Available online 6 September 2018Source: Tetrahedron LettersAuthor(s): Christine A. Arbour, Jennifer L. StockdillIn this manuscript, we establish the susceptibility of the N-methyldiaminobenzoyl linker to undergo undesired acylation during standard peptide capping with acetic anhydride. Successive capping treatments led to problematic levels of linker incapacitation. We describe a mild, inexpensive alternative capping strategy that is completely selective for the N terminus with no acylation of the linker detected for any of the substrates evaluated. The utility of this protocol is demonstrated via the synthesis of the CAPA-PVK-1 consensus sequence of the C. elegans neuropeptide-like protein precursor peptide NLP-44.Graphical abstractGraphical abstract for this article
       
  • Towards the total synthesis of Trichormamide A, a cyclic undecapeptide
    • Abstract: Publication date: Available online 6 September 2018Source: Tetrahedron LettersAuthor(s): Michel Gaillard, Sanjit Das, Mahamadou Djibo, Delphine Raviglione, Christian Roumestand, Baptiste Legrand, Nicolas InguimbertLipocyclopeptides isolated from marine sources hold great promise as new lead for therapeutics. Here, we propose the first attempt towards the total synthesis of Trichormamide A. This synthesis will help to confirm the proposed structure of the cyclic lipopeptide.Graphical abstractGraphical abstract for this article
       
  • Novel 5 H -[1,2,4]oxadiazolo[4,5- a ]pyrimidin-5-one derivatives as
           antibacterial and anticancer agents: synthesis and biological evaluation
    • Abstract: Publication date: Available online 5 September 2018Source: Tetrahedron LettersAuthor(s): Xiaoyu Liu, Xizhong Song, Yuwen Liu, Mingjin Xie, Wei Yu, Shengjiao Yan, Jun Lin, Yi JinA novel class of 5H-[1,2,4]oxadiazolo[4,5-a]pyrimidine derivatives was prepared, characterized, and tested for its antibacterial and anticancer potential against thirteen strains and five human cancer cell lines. The synthetic method was optimized, and a proposed reaction mechanism was also presented. The compounds containing the 5-bromo-pyrimidine moiety exhibited moderate antibacterial potencies against Gram-positive strains. Furthermore, the newly prepared compounds displayed selectively antiproliferative activity against human cancer cell lines. These current results will help us to further optimize and develop new drug candidates for clinical studies as novel antibacterial or anticancer agents.Graphical abstractGraphical abstract for this article
       
  • A metal-catalyst-free oxidative coupling of anilines to aromatic azo
           compounds in water using bleach
    • Abstract: Publication date: Available online 5 September 2018Source: Tetrahedron LettersAuthor(s): Gabriela F.P. de Souza, Theodora W. von Zuben, Airton G. SallesA simple route toward the synthesis of symmetrical and unsymmetrical aromatic azo compounds through oxidative coupling of anilines using widely available NaOCl is presented. This metal catalyst-free protocol is performed in water and affords the desired products in high yields.Graphical abstractGraphical abstract for this article
       
  • Imidazolidin-4-ones via (3+2) cycloadditions of aza-oxyally cations onto
           (E)-N-arylideneanilines
    • Abstract: Publication date: Available online 5 September 2018Source: Tetrahedron LettersAuthor(s): Oznur Eyilcim, Sezin Issever, Nuket Ocal, Scott Gronert, Ihsan ErdenIn the course of our studies on the chemistry of oxyallyl species we uncovered a new (3+2) cycloaddition of aza-oxyallyl systems, generated in situ from N-benzyloxy-2-chloroamides in the presence of NEt3, onto N-arylimines yielding imidazolidin-4-ones in moderate to good yields. The cycloadditions are regioselective. Computational modelling using DFT at the M062x/6-311+G∗∗ level is in support the observed regioselectivities. Although the path to the trans imidazolin-4-one is favored, the cis product is preferred by almost 8 kcal/mol and could be formed by base-catalyzed epimerization. All products were isolated by chromatography and characterized by means of their FTIR, NMR and HRMS data.Graphical abstractGraphical abstract for this article
       
  • Synthesis of flavonoid 2-deoxyglucosides via the Mitsunobu reaction
    • Abstract: Publication date: Available online 5 September 2018Source: Tetrahedron LettersAuthor(s): Ziyi Han, Zhiwei Zheng, Li Cai, Dandan Zhou, Changsheng Li, Qiang Sui, Shuai Liu, Qi GaoThe Mitsunobu reaction of flavonoids and 3,4,6-tri-O-acetyl-2-deoxy-D-glucopyranose or 3,4,6-tri-O-benzyl-2-deoxy-D-glucopyranose is a very effective method for the stereoselective synthesis of flavonoid 2-deoxyglucosides. Since there is no C2 substituent on the sugar moieties, the observed α- or β-stereoselectivity was mainly controlled by the (acetyl or benzyl) protecting groups. Possible mechanistic insights are offered to explain the dual stereoselectivity.Graphical abstractGraphical abstract for this article
       
  • Copper-Catalyzed Radical/Radical Cross-Coupling of Ketoxime Carboxylates
           with 4-Hydroxycoumarins: A Novel Synthesis of Furo[3,2-c]-coumarins
    • Abstract: Publication date: Available online 5 September 2018Source: Tetrahedron LettersAuthor(s): Mingchuang He, Zhaohua Yan, Wangyang Wang, Fuyuan Zhu Sen LinA novel and efficient strategy for the synthesis of furo[3,2-c]coumarins has been developed via copper-catalyzed radical/radical cross-coupling of ketoxime carboxylates with 4-hydroxycoumarins. This redox-neutral reaction allows smooth and selective synthesis of 2-substituted, 3-substituted, 2,3-disubstituted and 2,3-fused polycyclic furo[3,2-c]coumarins.Graphical abstractGraphical abstract for this article
       
  • An efficient synthesis of indoles via a CuMgAl-LDH-catalyzed cyclization
           of 2-alkynylsulfonanilides
    • Abstract: Publication date: Available online 5 September 2018Source: Tetrahedron LettersAuthor(s): Sheng-Yan Zhang, Shan-Gang Sun, Yu-Shuang Guo, Xiao-Fan Lu, Dian-Shun GuoA highly efficient method for the synthesis of indoles has been successfully developed via a CuMgAl-LDH-catalyzed intramolecular annulation reaction of 2-alkynylsulfonanilides. This CuMgAl-LDH catalyst features facile preparation, recovery, and reuse at least seven times without a marked loss in the catalytic activity, as well as the unique dual activation. Moreover, the crystal structures and Hirshfeld surface analysis of typical indole compounds were also presented.Graphical abstractGraphical abstract for this article
       
  • Cu(I)-Catalyzed Cascade Intramolecular Cyclization of 2-Propynol Phenyl
           Azides and Diarylphosphine Oxides for the Synthesis of Bisphosphorylated
           Indole Derivatives
    • Abstract: Publication date: Available online 4 September 2018Source: Tetrahedron LettersAuthor(s): Xian-Rong Song, Ren Li, Tao Yang, Jiang Bai, Ruchun Yang, Xi Chen, Haixin Ding, Qiang Xiao, Yong-Min LiangThe [Cu(OTf)]2. C6H6 catalyzed cascade intermolecular addition–intramolecular cyclization reaction of easily prepared 2-propynol phenyl azides and diarylphosphine oxides was developed. This novel reaction leads to simultaneous formation of one C—N and two C—P bonds in a single step to give bisphosphorylatd indole derivatives under mild conditions in moderate to good yields.Graphical abstractGraphical abstract for this article
       
  • Highly Selective Fluorescent Probe Based on a rhodamine B and
           furan-2-carbonyl chloride conjugate for Detection of Fe3+ in Cells
    • Abstract: Publication date: Available online 3 September 2018Source: Tetrahedron LettersAuthor(s): Yu Wang, Fan Song, Jing Zhu, Yuqi Zhang, Lei Du, Chun KanA furan-2-carbonyl chloride modified rhodamine B derivative (RBFC) has been designed and synthesized. The probe RBFC exhibited excellent sensitivity and selectivity for detection of Fe3+ with a 1:1 stoichiometry over other tested metal ions in a MeOH/H2O (1:1, v/v, pH 7.36, HEPES buffer, 1.3 mM) solution. The association constant and the detection limit were calculated to be 7.28×103 M-1and 0.437 μM based on fluorescence titration analysis. Furthermore, the probe RBFC was successfully applied in living cells, and the results indicated that the probe could monitor intracellular Fe3+ in MCF-7 cells.Graphical abstractA furan-2-carbonyl chloride modified rhodamine B derivative has been designed and synthesized. The probe exhibited excellent sensitivity and selectivity for detection of Fe3+ in a MeOH/H2O solution. And it could monitor intracellular Fe3+ in MCF-7 cells.Graphical abstract for this article
       
  • Hemicyanine-linked pyrimidine mimics as solvatochromic fluorophores with
           visible excitation wavelengths
    • Abstract: Publication date: Available online 3 September 2018Source: Tetrahedron LettersAuthor(s): Prashant S. Deore, Christopher J. Osuch, Richard A. MandervilleThe design of solvatochromic fluorescent nucleosides with visible excitation wavelengths is a goal towards the generation of modified oligonucleotides for fluorimetry-based molecular imaging. Herein, two hemicyanine-linked C5-2′-deoxyuridine nucleosides (PyI-dU and APPy-dU) have been synthesized by first generating hemicyanine-alkyne precursors that were attached via the alkyne moiety to 5-iodo-2′-deoxyuridine (5-I-dU) by Sonogashira coupling. The photophysical properties of the hemicyanine-linked dU probes have been characterized and compared to the corresponding properties of the hemicyanine-alkyne precursors. The nucleoside probe PyI-dU exhibits optical features that mimic the properties of the free hemicyanine-alkyne precursor, while the APPy-dU probe displays more favorable optical properties (longer excitation wavelength, brighter emission in water) than its precursor that is ascribed to π-stacking interactions between the hemicyanine dye with the dU nucleobase. Overall, probe APPy-dU is a superior solvatochromic fluorophore than PyI-dU suggesting its greater utility for fluorescent imaging applications.Graphical abstractGraphical abstract for this article
       
  • Copper-catalyzed cross-coupling of chloramine salts and arylboronic acids
           in water: a green and practical route to N-arylsulfonamides
    • Abstract: Publication date: Available online 1 September 2018Source: Tetrahedron LettersAuthor(s): Banlai Ouyang, Yanxia Zheng, Yi Liu, Fei Liu, Juying Yao, Yiyuan PengA green and practical method for the synthesis of N-arylsulfonamides from chloramine salts and arylboronic acids is herein developed. The reaction proceeds readily in the presence of 5 mol% of CuI and 2.5 equiv. K2CO3 in water at room temperature, generating a variety of N-arylsulfonamides in moderate to good yields with good functional group tolerance.Graphical abstractGraphical abstract for this article
       
  • Propylphosphonic anhydride (T3P®) mediated synthesis of
           3-oxoisoindoline-1-carboxamides from 2-formylbenzoic acid, amines, and
           isocyanides. Preparation of isoindolinone alkaloids
    • Abstract: Publication date: Available online 31 August 2018Source: Tetrahedron LettersAuthor(s): Valentina Varga, Mátyás Milen, Péter Ábrányi-BaloghPropylphosphonic anhydride (T3P®) was successfully applied to the synthesis of an isoindolinone library by the utilization of an Ugi four-center, three-component reaction (Ugi-4C-3CR). The use of T3P® significantly shortened the required reaction time and the corresponding products were obtained in good to high yields. Moreover, a side-reaction was observed when phenylethylamine derivatives and tryptamine were used as the amine component. The latter reaction was applied to the microwave-assisted, one-pot synthesis of the isoquinoline alkaloid (±)-nuevamine. Surprisingly, the traditional Ugi four-component reaction (Ugi-4CR) was unsuccessful in the presence of T3P®. In this case an α-amino amide was produced excluding the carboxylic acid from the multicomponent reaction.Graphical abstractGraphical abstract for this article
       
  • pK a values in organic chemistry – making maximum use of the available
           data
    • Abstract: Publication date: Available online 31 August 2018Source: Tetrahedron LettersAuthor(s): Agnes Kütt, Sigrid Selberg, Ivari Kaljurand, Sofja Tshepelevitsh, Agnes Heering, Astrid Darnell, Karl Kaupmees, Mare Piirsalu, Ivo LeitoAcids and bases are ubiquitous. Sometimes, it is essential to know the accurate strength (pKa values) of the acids/bases to work with, but sometimes just acidity/basicity order is enough. We often receive requests to measure pKa values of different substances in different solvents for answering questions like what acids can be used to protonate this substance or what base is able to deprotonate that compound? Such questions can, in fact, often be answered using published pKa data in different solvents. This digest/tutorial will give an overview of how to make efficient use of the existing pKa data.Graphical abstractGraphical abstract for this article
       
  • Photochromic DNA having fluorescent protein-inspired nucleosides
    • Abstract: Publication date: Available online 31 August 2018Source: Tetrahedron LettersAuthor(s): Akio Kobori, Taichiro Arai, Yuya Sakata, Takayuki Sugita, Asako Yamayoshi, Akira MurakamiMolecular switches controlled by light stimuli can be applicable to the variety of the biological application. In this study, skeletal structures of a chromophore of fluorescent protein were applied as aglycones of newly designed photochromic nucleosides, “Fluorescent protein-inspired nuceloside : FIN”. Phosphoramidite units of the photochromic nucleosides having imidazolinone derivatives with benzylidene or 3-pyridilidene groups were successfully synthesized for FIN-containing ODNs. Thermodynamic studies of the FIN-containing ODNs revealed that photo-irradiation with specific wavelength induced stability change of the duplexes.Graphical abstractGraphical abstract for this article
       
  • B(C6F5)3-Catalyzed Oxidative Deamination/Cyclization Cascade Reaction of
           Benzylamines and Ketones for the Synthesis of 2,4,6-Triarylpyridines
    • Abstract: Publication date: Available online 31 August 2018Source: Tetrahedron LettersAuthor(s): Fei Ling, Leixin Shen, Zhentao Pan, Lu Fang, Dingguo Song, Zhen Xie, Weihui ZhongThe B(C6F5)3-catalyzed oxidative deamination/cyclization cascade reaction of benzylamines and ketones for the construction of 2,4,6-triarylpyridines under metal-/solvent-free conditions has been successfully achieved. The advantages of this strategy include good functional group tolerance, low catalyst loading and high yields.Graphical abstractGraphical abstract for this article
       
  • Water Dispersed Gold Nanoparticles Catalyzed Aerobic Oxidative
           Cross-Dehydrogenative Coupling: An Efficient Synthesis of α-Ketoamides in
           Water
    • Abstract: Publication date: Available online 31 August 2018Source: Tetrahedron LettersAuthor(s): Narasimha Swamy Thirukovela, Ramesh Balaboina, Ravinder Vadde, Chandra Sekhar VasamAn effective green synthesis of α-ketoamides was developed for the first time in water via gold nanoparticles (AuNPs) catalyzed aerobic oxidative cross-dehydrogenative coupling of secondary amines with phenylglyoxals with a broad substrate scope.Graphical abstractGraphical abstract for this article
       
  • 6+6 macrocycles derived from 2,6-diformylpyridine and
           trans-1,2-diaminocyclohexane
    • Abstract: Publication date: Available online 30 August 2018Source: Tetrahedron LettersAuthor(s): Tomasz Paćkowski, Janusz Gregoliński, Katarzyna Ślepokura, Jerzy LisowskiWhile the non-templated reaction of racemic trans-1,2-diaminocyclohexane with 2,6-diformylpyridine leads to a mixture of 2+2 and 4+4 macrocyclic imines, the reaction of the isolated 2+2 macrocycle with cadmium(II) chloride results in the fusion of three smaller macrocyclic units into a large 6+6 macrocycle. The X-ray molecular structures of the hexanuclear cadmium complex of this macrocycle as well as the derived 6+6 protonated amine reveal multiply folded macrocycles that adopt container-type conformations.Graphical abstractGraphical abstract for this article
       
  • Synthesis of the trisoxazole macrolactone of mycalolides via
           template-directed E-selective ring-closing metathesis
    • Abstract: Publication date: Available online 30 August 2018Source: Tetrahedron LettersAuthor(s): Masaki Kita, Shun Watanabe, Hirotaka Oka, Hideo KigoshiThe trisoxazole macrolactone structure of marine macrolides, mycalolides A and B, was stereoselectively constructed by template-directed ring-closing metathesis (RCM) using Zn2+ coordination. 1D and 2D NMR analysis indicated that Zn2+ coordinates to the β-hydroxy ester and the two terminal oxazole N-atoms in the RCM precursor, and this coordination might restrict its transition state conformer to predominantly give the E-macrocycle.Graphical abstractGraphical abstract for this article
       
  • 2-Iodo benzoic acid: an unconventional precursor for the one pot
           multi-component synthesis of Quinoxaline using organo Cu (II) catalyst
    • Abstract: Publication date: Available online 29 August 2018Source: Tetrahedron LettersAuthor(s): Bittu Saha, Bijeta Mitra, Dhiraj Brahmin, Biswajit Sinha, Pranab GhoshThis is the first reported, unconventional, efficient strategy for the synthesis of quinoxaline from 2-iodo benzoic acid and sodium azide in presence of organo Cu (II) catalyst. Herein, a very simple, versatile one pot multi-component protocol for the synthesis of biologically active compound, quinoxaline has been described via Schmidt reaction and the nucleophilic substitution reaction. The isolated compounds were characterized by 1H NMR, 13C NMR. Our reported organo catalyst was characterized by single crystal XRD, SEM.Graphical abstractGraphical abstract for this article
       
  • Synthesis of magnetically separable catalyst Cu-ACP-Am-Fe3O4@SiO2 for
           Huisgen 1,3-dipolar cycloaddition
    • Abstract: Publication date: Available online 25 August 2018Source: Tetrahedron LettersAuthor(s): S.P. Vibhute, P.M. Mhaldar, S.N. Korade, D.S. Gaikwad, R.V. Shejawal, D.M. PoreThe present manuscript elicits the use of novel magnetically separable silica coated copper (Cu-ACP-Am-Fe3O4@SiO2) as a heterogeneous nanocatalyst for the Huisgen 1,3-dipolar cycloaddition reaction of alkyl or aryl halide, sodium azide and terminal alkyne, which provide a series of 1,4-disubstituted-1,2,3-triazoles. The catalyst was characterized by various physicochemical techniques such as Powder X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Spectroscopy(EDS), Thermogravimetric analysis (TGA-DSC), X-ray Photoelectron spectroscopy (XPS) and Vibrational sampling magnetometer (VSM). The acquisition of this nanocatalyst is also exemplified by employing reusability test and recycling of synthesized catalyst was achieved multiple times just by sequestering with an external magnet. It is noteworthy that the key-features like mild reaction conditions, simple work-up, High turnover number (TON), high turnover frequency (TOF), no use of hazardous organic solvents, easy recovery and reusability of the catalyst makes the present protocol more fascinating from an environmental and economic point of view.Graphical abstractGraphical abstract for this article
       
  • A Self-assembled tetrapeptide that acts as a “turn-on” fluorescent
           sensor for Hg2+ ion
    • Abstract: Publication date: Available online 23 August 2018Source: Tetrahedron LettersAuthor(s): Kalpana Tomar, Gagandeep Kaur, Sandeep Verma, Gurunath RamanathanThe tetrapeptide (Bz-ΔPhe(p-NPh2)-L-DOPA(protected)-L-Phe-L-Phe-OMe was designed to incorporate seven phenyl rings so that it’s conformation, self-assembly and application in Hg2+ ions sensing could be studied. Peptide molecules adopted an overlapping β-turn of type III/III conformation in crystals. The peptide showed a highly selective turn-on response towards mercuric ion over other metal ions with a 10-fold enhancement in fluorescence intensity. This intensity change coupled with the selectivity of the peptide towards mercury allowed us to demonstrate simple colorimetric dip sensing of Hg2+ ions. The technique provides a highly selective and effective way to detect Hg2+ ions. The peptide also self-assembled into nanospheres with diameter ranges from 100-500 nm. Mercuric ion coordination enabled these peptide nanospheres to aggregate into well-defined nanoparticles. The enhanced fluorescence upon Hg2+ addition demonstrates that peptide scaffolds can be exploited in the development of different selective sensors.Graphical abstractGraphical abstract for this article
       
  • CO2-Catalyzed/Promoted Transformation of Organic Functional
           Groups
    • Abstract: Publication date: Available online 21 August 2018Source: Tetrahedron LettersAuthor(s): Waldemar Schilling, Shoubhik DasCarbon dioxide is a cheap, non-toxic, abundant chemical and has been widely utilized in organic syntheses. Many new strategies have been developed using CO2 as a C1 building block and highly utilizable chemicals have been synthesized out of it. On the other hand, CO2-catalysed or promoted reactions can also be important from the environmental point of view. These reactions avoid toxic chemicals, expensive catalysts and often occur under mild reaction conditions. In this review, we would like to draw the summary about organic functional group transformation reactions that are promoted or catalyzed by CO2.Graphical abstractGraphical abstract for this article
       
  • Squaramide catalyzed α-chiral amine synthesis
    • Abstract: Publication date: Available online 21 August 2018Source: Tetrahedron LettersAuthor(s): Seda Karahan, Cihangir TanyeliEnantiomerically pure α-chiral amines, have been commonly utilized as resolving agents and chiral auxiliaries and are currently found in 40% of active pharmaceutical ingredients. Hence, development of highly stereoselective metal-free protocols regarding atom-economy and large-scale applications becomes a major issue. In this respect, chiral bifunctional H-bonding squaramides have been successfully applied for both amine synthesis and functionalization of amines in the last decade. This survey summarizes asymmetric synthesis of chiral amines by various carbon-carbon and carbon-nitrogen bond formation with squaramide catalysis as a particular focus of interest.Graphical abstractGraphical abstract for this article
       
  • Spiropyran-azobenzene-DBU System as Solvent Indicator
    • Abstract: Publication date: Available online 10 July 2018Source: Tetrahedron LettersAuthor(s): Zhiping Xu, Shen Li, Yujun Shen, Meijun Chen, Xusheng ShaoA dyad bearing azobenzene and spiropyran units was synthesized and its applications in indicating the polarity and protic or aprotic properties of a solvent were explored. The spiropyran-azobenzene derivative (SPAB) can be induced to different forms in different miscellaneous solvents accompanied with different color changes and spectral characteristics at the presence of organic base DBU. In a nonpolar or low-polar solvent, SPAB exists in thermostable spiropyran form with yellow color output. While in an aprotic polar solvent, the spiropyran part isomerized to merocyanine form giving a blue color. When SPAB is subjected to a protic solvent, the alkylation reaction occurs at the oxygen generating the alkylated-SPAB with red color. This solvent-dependent property can be used for discriminating solvent type.Graphical abstractGraphical abstract for this article
       
 
 
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