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Chain reaction: a perfect chemistry novel


Description: Chain reaction: a perfect chemistry novel
File name: Chain reaction: a perfect chemistry novel
Editorial board ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28
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Design of photoaffinity labeling probes derived from 3,4,5-trimethylfuran-2(5H)-one for mode of action elucidation ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Martin Pošta, Vilmos Soós, Petr Beier Herein we report the synthesis of new probes for photoaffinity labeling with the aim of receptor identification and mode of action elucidation of 3,4,5-trimethylfuran-2(5H)-one (TMB), recently identified in the smoke of burning vegetation as an efficient seed germination inhibitor. These photoaffinity probes consist of an ethynyl group that acts as a tag for introduction of an optional detectable marker unit by an appropriate chemoselective ligation method after the photo-cross-linking operation. Graphical abstract image
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In(OTf)3/acid co-catalyzed hydration of 1-haloalkynes to α-halomethyl ketones ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Ming Zeng, Rui-Xue Huang, Wen-Yi Li, Xiao-Wen Liu, Fu-Ling He, Yi-Yuan Zhang, Fang Xiao A novel and efficient In(OTf)3 and HOAc cooperatively catalyzed hydration of 1-haloalkynes is described. This method provides ready access to α-chloromethyl ketones, α-bromomethyl ketones and α-iodomethyl ketones in moderate to high yields from simple, inexpensive starting materials. A broad substrate scope is achieved, and the reaction is compatible with various functional groups, including alkoxy, trifluoromethyl, halide, hydroxyl, cyclohexyl, and heterocyclic groups. Graphical abstract image
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Synthesis, conformational analysis and biological evaluation of the lactam analogue of the cyclodepsipeptide apratoxin A ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Ruwen Yin, Wei Zhang, Guoyun Liu, Ping Wu, Choiwan Lau, Yingxia Li Apratoxin A, a cyclodepsipeptide isolated from a marine cyanobacterium, demonstrates potent cytotoxicity against cancer cell lines by a unique mechanism. A lactam analogue of apratoxin A, named as amidapratoxin A, was efficiently synthesized over 22 linear steps in 2.1% overall yield for the first time. The further conformation analysis was conducted by NMR techniques and computer-based molecular modeling. The results showed that the orientation of the benzene ring in tyrosine moiety, the iso-butyl in isoleucine moiety and hydroxyl group in Ahtmna moiety are quite different from that of apratoxin A, which might result in a significant decrease of the cytotoxicity. While further investigation is on the way, these results provide increased understanding of conformation-activity relationship for apratoxin family members which is an important complement to structure-activity relationship. Graphical abstract image
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NBS mediated one-pot regioselective synthesis of 2,3-disubstituted imidazo[1,2-a]pyridines and their unambiguous characterization through 2D NMR and X-ray crystallography ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Ranjana Aggarwal, Gulshan Singh, Dionisia Sanz, Rosa M. Claramunt, M. Carmen Torralba, M. Rosario Torres A simple and mild protocol towards the regioselective synthesis of 1-aryl/heteroaryl-1-(2-methylimidazo[1,2-a]pyridin-3-yl)methanones has been developed by one-pot condensation of 2-aminopyridine with 1,3-diketones involving the intermediacy of 2-bromo-1,3-diketones formed in situ from 1,3-diketones using N-bromosuccinimide (NBS) in DCM by stirring at room temperature. The structure of the regioisomer has been confirmed unambiguously by the rigorous multinuclear NMR [(1H–13C) HMBC, (1H–13C) HMQC, (1H–15N) HMBC] spectroscopy and X-ray crystallographic studies. Graphical abstract image
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Synthesis of β-amino alcohols using the tandem reduction and ring-opening reaction of nitroarenes and epoxides ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Chongyang Shi, Cheng Ren, Erlei Zhang, Huile Jin, Xiaochun Yu, Shun Wang A high yield one-pot synthesis of β-amino alcohols from nitroarenes and 1,2-epoxides was developed, which utilizes inexpensive iron dust as a reducing agent and NH4Cl as the only additive in a 50% (v/v) ethanol solution. This new efficient synthetic approach tolerates a wide range of functionalities. The mild reaction conditions (e.g., 60 °C), together with the use of low cost and readily available starting materials, make this synthetic approach an attractive alternative to the current synthesis of β-amino alcohols. Graphical abstract image
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Copper-catalyzed synthesis of 1-amino-5-arylindazolo[3,2-b]quinazolin-7(5H)-ones via a ring-opening reaction of 4-halogenated isatin ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Yong-Gang Ma, Chao Li, Chang-Sheng Yao, Xiang-Shan Wang The domino reaction of 4-halogenated isatins and 2-amino-N′-arylbenzohydrazides catalyzed by CuI in the presence of Cs2CO3 is described. A possible reaction mechanism containing the consecutive condensation, cyclization, C–N bond Ullmann coupling, ring-opening and decarboxylation is put forward according to the control experiments. This procedure provides an efficient method for the synthesis of fused polycyclic 1-amino-5-arylindazolo[3,2-b]quinazolin-7(5H)-ones derivatives in good yields. Graphical abstract image
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Sulfur-containing derivatives from (1R)-(−)-myrtenal designed as chiral ligands ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Mariola Zielińska-Błajet, Paweł Rewucki, Szymon Walenczak New chiral sulfur-containing derivatives were prepared in the diastereoselective nucleophilic additions of thiophenols to the commercially available (1R)-(−)-myrtenal. The newly synthesized 3-phenylsulfanyl derivatives containing an aldehyde functionality were successfully transformed into enantiopure compounds with S, Se and N-donor atoms and applied as chiral ligands in palladium-catalyzed asymmetric allylic alkylations (Tsuji–Trost reaction) providing products with enantioselectivities of up to 75% ee. Graphical abstract image
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Cu(I)/Ag(I)-mediated decarboxylative trifluoromethylation of arylpropiolic acids with Me3SiCF3 at room temperature ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Lingling Yang, Linlin Jiang, Yaming Li, Xinmei Fu, Rong Zhang, Kun Jin, Chunying Duan A novel Cu(I)/Ag(I)-mediated decarboxylative trifluoromethylation of arylpropiolic acids with Me3SiCF3 has been developed for the construction of Csp-CF3 bond under mild conditions. This method proceeds smoothly at room temperature and shows a widely functional compatibility, providing a series of corresponding trifluoromethylated acetylenyl-containing aromatics in good yields. Graphical abstract image
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Synthesis of wax esters and related trehalose esters from Mycobacterium avium and other mycobacteria ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Salam G. Taher, Juma'a R. Al Dulayymi, H. Giresse Tima, Hanan M. Ali, Marta Romano, Mark S. Baird The synthesis of mycobacterial mycolic acid related wax esters and of their trehalose di- and mono-esters is described. The trehalose dimycolates (TDMs) synthesised activated bone marrow derived dendritic cells (BMDCs) in vitro more strongly than trehalose dibehenate or the trehalose monomycolates (TMMs). The inflammatory effects were similar to those of TDM from either a synthetic keto- or methoxy-mycolic acid, but somewhat stronger than those of a TDM from an α-mycolic acid. In vivo, the effects of one wax ester TDM were similar to those of the methoxy-MA and α-mycolic acid TDMs and trehalose dibehenate. Graphical abstract image
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Synthesis of derivatives of methoxydibenzo[b, f]oxepine in the presence of sodium azide ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Hanna Krawczyk, Michał Wrzesiński, Damian Mielecki, Przemysław Szczeciński, Elżbieta Grzesiuk Dibenzo[b,f]oxepine is an important scaffold in medicinal chemistry and its derivatives occur in several medicinally important plants. A new approach to methoxydibenzo[b,f]oxepines (15–21) proceeding under mild reaction conditions, has been developed. Notably, the use of sodium azide in the reaction allows access to new substituted dibenzo[b,f]oxepines. In order to study their shape and conformation, the optimum structures of these compounds were calculated using the DFT B3LYP/6-311++G(2d,p) method. A docking simulation was performed to insert compound 20 into the crystal structure of tubulin at the colchicine binding site to determine the probable binding model. The information from this work can be helpful for the investigation of new tubulin polymerization inhibitors exhibiting stronger activity. Graphical abstract image
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Efficient synthesis of organic sulfonic acid derivatives containing dithiocarbamate side chains ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Bowen Li, Shuo Zhou, Shucheng Wang, Xingyi Sun, Zemei Ge, Runtao Li An efficient method for the synthesis of organic sulfonic acid potassiums containing dithiocarbamate side chains was developed through the reaction of amines, carbon disulfide and sultones in the presence of K3PO4 in water at room temperature. The organic sulfonic acid potassium derivatives are easily transformed into the corresponding organic sulfonic acids, which were further reacted with amines to afford the important organic sulfonamides containing dithiocarbamate side chains. Graphical abstract image
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Straightforward synthesis of ferrocenyl-based thioether and application as chemosensor for Hg2+ ion ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Qiang Teng, Yufeng Liu, Jianfeng Hu, Hao Chai, Kuofei Li, Hao Zhang A simple and efficient strategy of constructing ferrocene-based thioether ligands through metal-free reductive coupling of thiols with N-tosylhydrazones bearing a ferrocenyl group has been developed. This method features metal-free, good functional group tolerance, and readily available starting materials. Moreover, the compound 3k as a novel chemosensor has shown excellent recognition towards Hg2+ ion via optical and electrochemical signals. Quantification of the absorption titration analysis shows that the detection limit was 9.56×10−7 M for 3k-Hg2+. Graphical abstract image
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Stereocontrolled synthesis of (S)-9-cis- and (S)-11-cis-13,14-dihydroretinoic acid ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Belén Vaz, Rosana Alvarez, Angel R. de Lera The 9-cis and 11-cis stereoisomers of 13,14-dihydroretinoic acid with S configuration, (S)-7 and (S)-9, respectively, have been synthesized stereoselectively. The former has been recently characterized as the first endogenous natural ligand of the retinoid X receptor (RXR). The Julia-Kocienski reaction of allyl sulfones and aldehydes was used as connective step and afforded the Z isomer of a trienyl ester accounting for the entire side chain of the targets. A highly selective and unidirectional iodine-induced isomerization of a Z,Z,E triene to the desired E,Z,E isomer was required prior to the synthesis of (S)-7 via a Suzuki cross-coupling. The same approach to (S)-9 led to substantial isomerization when the Suzuki cross-coupling was used as the last bond-forming reaction. As alternative, the two bond-forming steps were exchanged and the synthesis of (S)-9 was completed using the Z-selective Julia-Kocienski reaction. Graphical abstract image
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Multifunctional heterocyclic scaffolds for hybrid Lewis acid/Lewis base catalysis of carbon–carbon bond formation ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Dennis Wiedenhoeft, Adam R. Benoit, Yibiao Wu, Jacob D. Porter, Elisia Meyle, Teresa H.W. Yeung, Raechel Huff, Sergey V. Lindeman, Chris Dockendorff Several new classes of hybrid catalysts have been synthesized by tethering heterocyclic metal (Lewis acid) chelating scaffolds to several different amines capable of facilitating enamine catalysis. Oxazole, thiazole, and imidazole-based chiral precatalysts were prepared in several steps from amino acid starting materials, and these were combined with a variety of metal Lewis acids for potential use as catalysts for various carbon–carbon bond formations. Air- and moisture-tolerant catalysts for enantioselective direct aldol reactions with activated benzaldehyde acceptors were identified, with optimal results obtained with proline-derived oxazole–carboxamide precatalysts combined with Zn(OTf)2 or lanthanide (III) salts. Control studies support the hypothesis that these act as unimolecular hybrid catalysts for the aldol reaction of propionaldehyde and 4-nitrobenzaldehyde. Graphical abstract image
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Brønsted acid promoted one-pot synthesis of 4-aryl-3,4-dihydrocoumarins ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Cheng Chen, Rui Zhang, Long Lin, Guang-Fu Yang, Qiong-You Wu 4-Aryl-3,4-dihydrocoumarins are a class of valuable molecules demonstrating attractive pharmaceutical and biological properties. In this paper, we designed a new and facile approach to synthesis of 4-aryl-3,4-dihydrocoumarin derivatives by Brønsted acid catalyzed Friedel–Crafts alkylation and cycloaddition reaction. With this protocol, 15 examples of 4-aryl-3,4-dihydrocoumarins were successfully prepared with yields ranging from 82 to 99%. Graphical abstract image
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A new convenient synthetic approach to diarylpyrimidines ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Antonio Guirado, Enrique Alarcón, Yesica Vicente, Raquel Andreu, Delia Bautista, Jesús Gálvez A new synthetic method in pyrimidine chemistry has been developed. 2,2,2-Trichloroethylideneacetophenones, easily available from chloral and acetophenones, reacted with benzamidines to provide novel 2,6-diaryl-6-hydroxy-4-trichloromethyl-1,4,5,6-tetrahydropyrimidines in near quantitative yields. Efficient dehydration of these compounds gave previously unknown 2,4-diaryl-6-trichloromethyl-1,6-dihydropyrimidines, which were found able to undergo base-induced chloroform elimination to give 2,4-diarylpyrimidines in high yields. Molecular structures for final and intermediate compounds were determined by single crystal X-ray diffraction. A main improvement of this procedure lies in circumventing the oxidative aromatization of dihydropyrimidine intermediates through a chloroform elimination process. The diarylpyrimidines were also found directly accessible by a fair yield one-pot procedure. Graphical abstract image
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A single chemosensor for the detection of dual analytes Cu2+ and S2− in aqueous media ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Dae Yul Park, Ka Young Ryu, Jin Ah Kim, So Young Kim, Cheal Kim A multifunctional colorimetric chemosensor 1, N-(2-((2,4-dinitrophenyl)amino)phenyl)-2-((2-hydroxyethyl)amino)acetamide was synthesized and used to sense Cu2+ and S2− in aqueous solution. The sensor 1 showed highly selective colorimetric responses to Cu2+ and S2− by immediately changing its color from pale yellow to light green and pink, respectively, without any interference from other metal ions and anions. Especially, 1 can detect Cu2+ (10.1 μM) below the guideline (31.5 μM) of WHO. Moreover, the sensor 1 could be used to quantify Cu2+ ion in water samples. The sensing mechanism of Cu2+ by 1 were proposed to be a metal-to-ligand charge-transfer (MLCT) with the experimental results and theoretical calculations, and that of S2− by 1 proposed to be a deprotonation process. Graphical abstract image
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Enantio-and diastereoselective desymmetrization of α-alkyl-α-diazoesters by dirhodium(II)-catalyzed intramolecular C–H insertion ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Taku Miyazawa, Kazushi Minami, Motoki Ito, Masahiro Anada, Shigeki Matsunaga, Shunichi Hashimoto The first enantio-and diastereoselective construction of fused bicyclic ring systems via intramolecular C–H insertion reaction of σ-symmetric α-alkyl-α-diazoesters is described. With dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh2(S-PTTL)4, the C–H insertion proceeded in a chemoselective manner to give methyl bicyclo[3.3.0]oct-7-ene-2-carboxylate and methyl bicyclo[4.3.0]nonane-7-carboxylate derivatives with up to 99% ee and perfect cis diastereoselectivity. The utility of this protocol was demonstrated by the catalytic asymmetric synthesis of a key intermediate in Whitesell's synthesis of udoteatrial hydrate. Graphical abstract image
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Enhanced liquid crystal properties in symmetric ethers containing the oxazepine core: synthesis and characterization of seven member heterocyclic dimers ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): AbdulKarim-Talaq Mohammad, H.T. Srinivasa, S. Hariprasad, Guan-Yeow Yeap Four new series of symmetric dimers derived from the basic heterocyclic oxazepine core were designed, synthesized, characterized and investigated for liquid crystal properties. The chemical structures of the prepared molecules were characterized by infrared, 1H/13C nuclear magnetic resonance spectra and elemental analysis. Thermal properties and mesophase textures were evaluated by using a combination of differential scanning calorimetry and polarized optical microscopy techniques. Most of the compounds exhibited monotropic liquid crystalline phases in cooling processes. The effect of the spacer chain length and terminal alkoxy chain were studied for the influence on the type of mesophase formed by the homologous series of compounds. Lower members possessing the methylene spacer and a terminal alkoxy-chain favoured smectogenic properties; those derived from medium methylene spacer with terminal alkoxy chain favoured nematogenic properties whereas molecules derived with a higher methylene spacer with terminal alkoxy chain members did not favour any liquid crystalline properties. Graphical abstract image
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A one-pot three-component synthesis of dithiocarbamates starting from vinyl pyridines and vinyl pyrazine under solvent- and catalyst-free conditions ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Azim Ziyaei Halimehjani, Jürgen Martens, Torben Schlüter A novel and efficient one-pot three-component reaction for the synthesis of dithiocarbamates at room temperature under solvent- and catalyst-free conditions, starting from readily available amines, CS2 and vinyl pyridines and vinyl pyrazine is reported. Excellent yield, green reaction conditions, and complete regioselectivity toward anti-Markovnikov adducts are particular advantages of this work. Graphical abstract image
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Synthesis and characterization of two new tetrapyrazolic macrocycles for the selective extraction of cesium cation ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Tarik Harit, Fouad Malek, Brahim El Bali, Michal Dusek, Monika Kucerakova The synthesis of two macrocycles containing two bipyrazolic subunits, with different side arms is reported. These structures were characterised by 1H NMR, 13C NMR, mass spectroscopy and elemental analysis. The macrocycle bearing a hydroxyl group in the side arms, crystallizes in triclinic (S.G.: P-1) systems, with the unit cell parameters: [11.3086(4), 13.6865(5), 14.6311(5), 108.774(3), 105.408(3), 107.131(3), V=1879.28(15) Å3]. It possesses 3D crystal structure with molecules interacting through weak H-bonds. The complexing properties of new macrocycles towards alkaline metal ions (Li+, Na+, K+ and Cs+) were studied by a liquid–liquid extraction process. The percentage values of extraction were determined by atomic absorption measurements and UV spectroscopy. Their macrocyclic cavities are better adapted to extract the Cs+ cation. The macrocycle with side chains bearing donor groups shows the best extraction due to its participation in complexation. Graphical abstract image
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Preparation of enantiomerically enriched aromatic β-hydroxynitriles and halohydrins by ketone reduction with recombinant ketoreductase KRED1-Pglu ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Martina L. Contente, Immacolata Serra, Francesco Molinari, Raffaella Gandolfi, Andrea Pinto, Diego Romano A NADPH-dependent benzil reductase (KRED1-Pglu) was used as recombinant enzyme for catalysing the reduction of different functionalised ketones. The reactions were carried out in the presence of a catalytic amount of NADP+ and an enzyme-coupled transformation (oxidation of glucose catalysed by glucose dehydrogenase), for regenerating the cofactor and thus driving the reaction to completion. KRED1-Pglu showed remarkable versatility, being able to reduce different β-ketonitriles and α-haloketones at different pHs; notably, depending on the nature of the substrate, KRED1-Pglu can be used for efficient and clean enzymatic reduction, avoiding side-reactions due to the pH of the medium. The reduction generally occurred with high enantioselectivity, allowing the preparation of enantiomerically enriched β-hydroxynitriles and halohydrins in high yields; the stereochemical outcome of the reduction followed in all the cases the so-called Prelog's rule. Graphical abstract image
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A simple benzimidazole quinoline-conjugate fluorescent chemosensor for highly selective detection of Ag+ ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Changjun Chen, Haiyang Liu, Bin Zhang, Yanwei Wang, Kai Cai, Ying Tan, Chunmei Gao, Hongxia Liu, Chunyan Tan, Yuyang Jiang A novel and simple fluorescent chemosensor (L), N-((1H-benzo[d]imidazol-2-yl)methyl)quinoline-2-carboxamide, based on quinoline benzimidazole scaffold was synthesized successfully, which had a ‘turn-on’ effect for Ag+ detection in methanol/Tris buffer(1:1, v/v, pH=7.35) and exhibited a strong fluorescence emission at 357 nm (λ ex=300 nm). The chemosensor had high sensitivity and selectivity for Ag+ even in the presence of other metal ions with the detection limit of 4.4×10−7 M, which reached the standard of World Health Organization (WHO) for drinking water (5.0×10−7 M). The mechanism of the interaction between the sensor and Ag+ was investigated in detail through NMR and MALDI Mass spectra analysis. Graphical abstract image
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DBU mediated confluent approach for the one pot synthesis of novel 5-hydroxy pyrazolo[1,2-a][1,2,4]triazoles and their dehydration to novel pyrazolo[1,2-a][1,2,4]triazole derivatives ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Shruti Gupta, Pooja Saluja, Jitender M. Khurana A series of novel alkyl 5-hydroxy-7-aryl-5-methyl-1,3-dioxo-2-phenyl hexahydropyrazolo[1,2-a][1,2,4]triazole-6-carboxylates and alkyl 5-aryl-7-methyl-1,3-dioxo-2-phenyl-1,2,3,5-tetra hydropyrazolo[1,2-a][1,2,4]triazole-6-carboxylates have been synthesized. The synthesis of hydroxy pyrazolo[1,2-a][1,2,4]triazoles has been achieved by DBU mediated one pot reaction of aromatic aldehydes, alkyl acetoacetates and 4-phenylurazole at 35 °C in ethanol–water (1:1). Dehydration of hydroxy pyrazolo[1,2-a][1,2,4]triazoles has been achieved using conc. H2SO4 to afford dehydrated pyrazolo[1,2-a][1,2,4]triazoles in high yields. The structural assignments have been made by spectral data and unambiguously confirmed by X-ray analysis. Good yields, operational simplicity and moderate conditions are the advantages of the reactions. Graphical abstract image
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An efficient method for the stereoselective synthesis of N-substituted trihydroxypiperidine derivatives promoted by p-TsOH ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Wen Yuan, Jianhui Xia, Xiaoke Zhang, Peng Liang, Jichao Zhang, Wei Jiao, Huawu Shao An effective and facile method for the synthesis of N-substituted trihydroxypiperidine derivatives is described. The Mannich-type reaction of protected 5-O-tosylate pentoses with amines and ketones in the presence of p-TsOH provides convenient access to the stereoselective synthesis of N-substituted iminosugar C-glycosides as potential glucosidase inhibitors in good to excellent yields. Graphical abstract image
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Synthesis of (2R,8′S,3′E)-δ-tocodienol, a tocoflexol family member designed to have a superior pharmacokinetic profile compared to δ-tocotrienol ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Xingui Liu, Satheesh Gujarathi, Xuan Zhang, Lijian Shao, Marjan Boerma, Cesar M. Compadre, Peter A. Crooks, Martin Hauer-Jensen, Daohong Zhou, Guangrong Zheng A group of side chain partially saturated tocotrienol analogues, namely tocoflexols, have been previously designed in an effort to improve the pharmacokinetic properties of tocotrienols. (2R,8′S,3′E)-δ-Tocodienol (1) was predicted to be a high value tocoflexol for further pharmacological evaluation. We now report here an efficient eight-step synthetic route to compound 1 utilizing naturally-occurring δ-tocotrienol as a starting material (24% total yield). The key step in the synthesis is oxidative olefin cleavage of δ-tocotrienol to afford the chroman core of 1 with retention of chirality at the C-2 stereocenter. Graphical abstract image
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An easy access to fused chromanones via rhodium catalyzed oxidative coupling of salicylaldehydes with heterobicyclic olefins ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Ajesh Vijayan, T.V. Baiju, E. Jijy, Praveen Prakash, M. Shimi, Nayana Joseph, Petri M. Pihko, Sunil Varughese, K.V. Radhakrishnan Herein we describe a detailed study on the rhodium catalyzed oxidative coupling of salicylaldehydes with heterobicyclic olefins such as diazabicyclic olefins and urea-derived bicyclic olefins. The developed method provides an ideal route to fused chromanone systems in a single synthetic step. Moreover, the scope of this methodology was extended to different oxa/aza-bridged bicyclic urea derivatives. Graphical abstract image
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Practical modification of peptides using ligand-free copper-catalyzed azide–alkyne cycloaddition ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Yoshiaki Kitamura, Ryuto Sakamoto, Takao Shiraishi, Haruka Oguri, Satoshi Ohno, Yukio Kitade A convenient method for the post-modification of any peptide bearing a disulfide bond via rapid ligand-free copper-catalyzed azide–alkyne cycloaddition (CuAAC) was developed. N-hydroxysuccinimide (NHS) esters and maleimides bearing an aryl acetylene residue to allow installation of a terminal alkyne moiety into peptides were efficiently synthesized. The ligation of glutathione (GSH) using the maleimides and disulfide-linked dimer of GSH (GSSG) using the NHS esters proceeded smoothly to afford the corresponding terminal alkyne-labeled glutathione derivatives, respectively. The terminal alkyne-labeled GSH and GSSG efficiently coupled with 4-fluorobenzylazide to provide the corresponding glutathione analogues in quantitative yield. In any case, side reactions including cleavage of disulfide bonds were not observed. The application of somatostatin, disulfide-linked cyclic tetradecapeptide, to this method was achieved. Graphical abstract image
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Synthesis of type III isomers of diacetyldeutero-, hemato-, and protoporphyrins with the use of Knorr's pyrrole ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Saburo Neya, Tomoki Yoneda, Tyuji Hoshino, Akira T. Kawaguchi, Masaaki Suzuki Derivation of the Knorr's pyrrole with 2-ethyl and 4-benzyl mixed-ester groups into 3,3′-diacetyl-5,5′-diiodo-4,4′-dimethyl-2,2′-dipyrromethane was developed. Coupling of the dipyrromethane with 5,5′-diformyl-3,3′-bis(2-methoxycarbonylethyl)-4,4′-dimethyl-2,2′-dipyrro-methane afforded in a reasonable yield diacetyldeuteroporphyin III with C2v symmetry. The porphyrin was further converted to protoporphyrin III through hematoporphyrin III. Utilization of readily available Knorr's pyrrole as the starting material much facilitates the access to symmetric iron porphyrins which are free from the orientational disorder in hemoprotein pocket. Graphical abstract image
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A chemoenzymatic route to chiral siloxanes ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Ravi Naoum, Jacqueline P. Séguin, John F. Trant, Mark B. Frampton, Tomáš Hudlický, Paul M. Zelisko An approach employing two enzymes—toluene dioxygenase and immobilized lipase B from Candida antarctica (N435)—was explored as a potential biocatalytic method for the coupling of chiral diols with siloxane species. Analysis of reaction mixtures using 1H NMR spectroscopy suggested that up to 66% consumption of the siloxane starting materials had occurred. Oligomeric species were observed and chiral products from the coupling of a cyclic diol with a siloxane molecule were isolated and characterized by MALDI-ToF MS and GPC. Immobilized lipases from Rhizomucor miehei and Thermomyces lanuginosus were also explored as potential catalysts for the coupling reactions, however, their use only returned starting material. Graphical abstract image
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Unsymmetrical α,ω-end-functionalized oligo(cyclohexylidenes): efficient synthesis and conformational analysis ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Waël Zeinyeh, Sylvie Radix, Raphaël Terreux, Julie-Anne Chemelle, Nadia Walchshofer The title compounds were efficiently synthesized by decarboxylative dehydration of β-hydroxy acids. This iterative process allowed to obtain bis- and ter-cyclohexylidenes with good yield. The conformations of trans and cis isomers of an unsymmetrical α,ω-end-functionalized biscyclohexylidene were studied by NMR and DFT methods. Graphical abstract image
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Nonlinear optical and energy-level modulation of organic alkynes by click chemistry ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Zongcheng Miao, Huihui Han, Dong Wang, Hong Gao, Jianming Gu, Huiying Hu A series of novel donor–acceptor chromophores have been successfully synthesized in excellent yield by metal-free [2+2] click chemistry, which was effective in the energy-level modulation of organic the π-conjugation aniline derivatives. Meanwhile, structures of all products were fully characterized by NMR, IR, and MS. UV–vis spectra were enlarged with end-absorptions into the near infrared region in varying degrees by introducing TCNE, TCNQ, F4-TCNQ click reagents and correspondingly electrochemical tests revealed that the energy levels of HOMO and LUMO were effectively tuned. The third order nonlinear optical properties studied at 532/1064 nm with picosecond Z-scan techniques indicated that almost all products exhibited the high NLO properties, especially, for dye c 5 , exhibiting third-order susceptibility χ(3)=1.83×10−7 esu under laser beam at 1064 nm. Graphical abstract image
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Asymmetric synthesis of pyrano[2,3-c]pyrazoles via a cascade reaction between Morita–Baylis–Hillman acetates of nitroalkenes and pyrazolones ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Jin Xie, Feng Sha, Xin-Yan Wu The first organocatalytic enantioselective cascade reaction of Morita–Baylis–Hillman acetates of nitroalkenes with pyrazolones has been developed. With 20 mol% of chiral tertiary-amine squaramide, 1,4,5,6-tetrahydropyrano[2,3-c]pyrazoles were afforded in moderate yields (up to 71%) with excellent stereoselectivities (up to>99:1 dr and up to 98% ee). Graphical abstract image
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Copper-catalyzed synthesis of 1,3,4-trisubstituted and 1,3,4,5-tetrasubstituted pyrazoles via [3+2] cycloadditions of hydrazones and nitroolefins ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Chong Shi, Chaowei Ma, Haojie Ma, Xiaoqiang Zhou, Jinhui Cao, Yuxing Fan, Guosheng Huang A highly economical and efficient copper(I)-catalyzed regioselective method for the synthesis of 1,3,4-trisubstituted and 1,3,4,5-tetrasubstituted pyrazoles via [3+2] cycloaddition of hydrazones and nitroolefins has been reported. This process displays excellent applicability with a wide range of substrates under mild conditions. Graphical abstract image
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Highly efficient and recyclable magnetic nanoparticles-supported gold(III)-bipy catalyst for oxidative α-cyanation of tertiary amines ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Weisen Yang, Li Wei, Feiyan Yi, Mingzhong Cai Oxidative α-cyanation of tertiary amines with trimethylsilyl cyanide was achieved by using a magnetic nanoparticles-supported gold(III)-bipy complex as catalyst to afford the corresponding α-aminonitriles in good to excellent yields in the presence of tert-butyl hydroperoxide under acid-free conditions. The new heterogeneous gold catalyst can easily be separated from the reaction mixture by using an external magnet and can be recycled for at least 10 times without any loss of activity. Graphical abstract image
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A route to benzylic arylsulfoxides from β-ketosulfoxides ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Meng-Yang Chang, Yu-Chieh Cheng, Chieh-Kai Chan The K2CO3-mediated benzylation of β-ketosulfoxides 4 with 2.0 equiv of benzylic halides 5 affords benzylic arylsulfoxides 6 in moderate yields along with trace amounts of chalcones 7. The products 6 are assumed to form in situ intermediates of sulfenate anions from β-ketosulfoxides which are commonly involved in carbon–sulfur bond formation. A plausible mechanism has been proposed. Graphical abstract image
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l-Proline and thiourea co-catalyzed condensation of acetone ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Lin Xu, Fang Wang, Jiejun Huang, Chenggen Yang, Lei Yu, Yining Fan Amino acid and primary amine/amide co-catalyzed acetone condensation was investigated. It was found that l -proline had overwhelming catalytic activity over other amino acids as well as the analogues with similar structures. Surprisingly, thiourea, a very cheap and stable chemical, was found to be the favorable co-catalyst. Co-catalyzed by the recyclable l -proline and thiourea, condensation of acetone led to the useful products mesityl oxide (MO), diacetone alcohol (DAA) and isophorone (IP) in the excellent 96.3% total selectivity. Graphical abstract image
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Synthesis and optical properties of novel Tröger's base derivatives ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Rui Yuan, Ming-qi Li, Jiang-biao Xu, Shu-ying Huang, Sheng-liang Zhou, Peng Zhang, Jin-juan Liu, Hui Wu Diphenylamine, phenothiazine or carbazole were introduced into Tröger's base skeleton via Ullmann or Suzuki coupling to afford new TB derivatives. Their optical properties tests, density functional theory (B3LYP; 6-31G) calculations were investigated. Incidentally anti-cancer activity against human hepatoma HepG2 cells in vitro (MTT assay) were investigated. All the results indicated that these novel compounds have the potential as fluorescence materials. Graphical abstract image
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Ubiquitin 7-amino-4-carbamoylmethylcoumarin as an improved fluorogenic substrate for deubiquitinating enzymes ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Yi-Tong Li, Yi-Chao Huang, Yang Xu, Man Pan, Yi-Ming Li A new fluorogenic substrate Ub-ACC (ubiquitin C-terminal 7-amino-4-carbamoylmethyl-coumarin) was developed for DUB (deubiquitinating enzyme) activity assays. This substrate can be synthesized with higher efficiency than the classical DUB substrate, Ub-AMC (ubiquitin C-terminal 7-amino-4-methylcoumarin). DUB assays using UCH-L3, OTUD2 and USP30 demonstrated that Ub-ACC shows nearly 2-fold higher sensitivity than Ub-AMC. Graphical abstract image
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Synthesis, conformational analysis and SAR research of OSW-1 analogues ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Chao Liu, A-peng Wang, Longlong Jin, Yanshen Guo, Yan Li, Zhehui Zhao, Pingsheng Lei A series of novel OSW-1 analogues were synthesized by coupling disaccharides (2-O-4-methoxylbenzoyl-β-d-xylopyranosyl-(1→3)-2-O-acetyl-α-l-arabinopyranosyl) or (2-O-4-(E)-cinnamoyl-β-d-xylopyranosyl-(1→3)-2-O-acetyl-α-l-arabinopyranosyl) and their 1→4 linked analogues [(2-O-4-methoxylbenzoyl-β-d-xylopyranosyl-(1→4)-2-O-acetyl-α-l-arabinopyranosyl) or (2-O-4-(E)-cinnamoyl-β-d-xylopyranosyl-(1→4)-2-O-acetyl-α-l-arabinopyranosyl)] with three different steroidal sapogenins at 16β-hydroxy. Their conformation was analyzed with NMR spectroscopy and molecule simulation. The arabinose moiety of 1–3 linked analogues was in chair conformation and 1–4 linked analogues was in boat conformation. 1–3 linked analogues exhibited potent anti-proliferation activity against a panel of human tumor cells at nanomolar concentration level, while 1–4 linked analogues did not show antitumor activity. This work should provide an evidence that the conformation plays an important role in the antitumor activity. Graphical abstract image
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Utilization of the inherent nucleophile for regioselective O-acylation of polyphenols via an intermolecular cooperative transesterification ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Jingchao Liu, Junjie Fu, Wenlong Li, Yu Zou, Zhangjian Huang, Jinyi Xu, Sixun Peng, Yihua Zhang A green and efficient method for regioselective O-acylation of polyphenols has been developed. The acylation can be carried out in potassium carbonate/dimethyl sulphoxide system by utilizing the ‘inherent nucleophile’ via an intermolecular cooperative transesterification under mild condition. This method shows particular advantage in regioselective acylation of polyphenols bearing 2′,4′-dihydroxyacetophenone moiety and can be extended to the synthesis of mono or multiple acetates of polyphenols without this moiety in good yields. Compared with other reported approaches, this method is endowed with atom economy and is more environment-friendly for avoiding the use of any metal-based catalysts. Graphical abstract image
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Copper-catalyzed selective syntheses of Markovnikov-type hydrothiolation products and thioacetals by the reactions of thiols with alkenes bearing heteroatoms ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Hui Xi, Enlu Ma, Zhiping Li Catalyst-controlled divergent reactions of thiophenols with alkenes bearing heteroatoms have been developed. Markovnikov-type hydrothiolation products and thioacetals were synthesized selectively by switching copper catalysts. Graphical abstract image
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Synthesis of surface-active N-heterocyclic carbene ligand and its Pd-catalyzed aqueous Mizoroki–Heck reaction ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Toshiaki Taira, Takaya Yanagimoto, Kenichi Sakai, Hideki Sakai, Akira Endo, Tomohiro Imura A surface-active N-heterocyclic carbene (NHC) ligand with an octaethylene glycol monomethyl ether and n-dodecyl chain was synthesized. The NHC and its Pd complex behaved as a general surfactant, and hydrophobic oily substrates such as iodobenzene and styrene were emulsified in water, resulting in the acceleration of the Mizoroki–Heck reaction under heterogeneous conditions. Our results demonstrated that the reactive emulsion interface rendered by the surface-active NHC is effective for the aqueous Mizoroki–Heck reaction. Graphical abstract image
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One-pot synthesis of polyhydropyrido[1,2-a]indoles and tetracyclic quinazolinones from 2-arylindoles using copper-mediated oxidative tandem reactions ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Mitsuaki Yamashita, Yukari Nishizono, Seiya Himekawa, Akira Iida We developed facile one-pot methods for the transformation of 2-arylindoles to polyhydropyrido[1,2-a]indoles and tetracyclic quinazolinones. The copper-catalyzed oxidation of 2-arylindoles to C-acylimines followed by aza-Diels–Alder reactions or oxidative ring-expansion reactions afforded significant polycyclic heterocycles. Graphical abstract image
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Metal-free C–H arylation of aminoheterocycles with arylhydrazines ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Toshihide Taniguchi, Mitsutaka Imoto, Motonori Takeda, Fukashi Matsumoto, Takeo Nakai, Masatoshi Mihara, Takumi Mizuno, Akihiro Nomoto, Akiya Ogawa A direct C–H arylation of aminoheterocycles with arylhydrazine hydrochlorides was developed. The reaction proceeds via a homolytic aromatic substitution mechanism involving aryl radicals as the intermediates. The new reaction takes place readily at room temperature in air and in the presence of an inexpensive base. Moreover, the reactivity of this radical arylation correlated with the HOMO energy of aminoheterocycles. This method provides not only a rapid access to diverse arylated heterocycles, but also an atom-efficient alternative to conventional transition-metal-catalyzed cross-coupling between halides and organometallics. Graphical abstract image
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Dipeptide-derived multifunctional phosphonium salt as a catalyst to synthesize highly functionalized chiral cyclopentanes ()
Publication date: 7 July 2016 Source:Tetrahedron, Volume 72, Issues 27–28 Author(s): Yingpeng Lu, Dongdong Cao, Jiaxing Zhang, Hongyu Wang, Gang Zou, Gang Zhao Asymmetric tandem Michael–Michael reactions between 2-substituted malonates and low reactive enones have been achieved by using novel dipeptides-derived phosphonium salts, affording the synthetically useful and highly functionalized chiral cyclopentanes with good yields, diastereoselectivities and high enantioselectivities. Graphical abstract image
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Editorial board ()
Publication date: 30 June 2016 Source:Tetrahedron, Volume 72, Issue 26
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Tetrahedron Young Investigator Award ∼ 2016 ()
Publication date: 30 June 2016 Source:Tetrahedron, Volume 72, Issue 26
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Literature ()
Publication date: 30 June 2016 Source:Tetrahedron, Volume 72, Issue 26
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