- Switching of macromolecular helicity of optically active poly(phenylacetylene)s bearing cyclodextrin pendants induced by various external stimuli
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A series of novel phenylacetylenes bearing optically active cyclodextrin (CyD) residues such as α-, β-, and γ-CyD and permethylated β-CyD residues as the pendant groups was synthesized and polymerized with a rhodium catalyst to give highly cis-transoidal
- Maeda, Katsuhiro,Mochizuki, Hiroaki,Watanabe, Masaki,Yashima, Eiji
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- Helical polymer brushes with a preferred-handed helix-sense triggered by a terminal optically active group in the pendant
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Helical polymer brushes with a preferred-handed helix-sense composed of a poly(phenylacetylene) backbone and poly(phenyl isocyanate) pendants are synthesized. The helix-sense of the backbone is effectively controlled by the helical chirality of the pendan
- Maeda, Katsuhiro,Wakasone, Shiho,Shimomura, Kouhei,Ikai, Tomoyuki,Kanoh, Shigeyoshi
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- Helical stereoregular artificial glycoconjugate polymers based on poly(phenylacetylene) backbone: Synthesis and molecular recognition with lectin
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Stereoregular poly(phenylacetylene)s bearing pendant lactose and cellobiose moiety were synthesized by polymerization of β-N-glycosylated 4-ethynylbenzamides with [Rh(nbd)Cl]2 (nbd=norbomadiene) as initiator. The glycoconjugate polymer possesse
- Matsuura, Kazunori,Furuno, Shin-Ichi,Kobayashi, Kazukiyo
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- Iron-Catalyzed Tertiary Alkylation of Terminal Alkynes with 1,3-Diesters via a Functionalized Alkyl Radical
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Direct oxidative C(sp)?H/C(sp3)?H cross-coupling offers an ideal and environmentally benign protocol for C(sp)?C(sp3) bond formations. As such, reactivity and site-selectivity with respect to C(sp3)?H bond cleavage have remained a persistent challenge. Herein is reported a simple method for iron-catalyzed/silver-mediated tertiary alkylation of terminal alkynes with readily available and versatile 1,3-dicarbonyl compounds. The reaction is suitable for an array of substrates and proceeds in a highly selective manner even employing alkanes containing other tertiary, benzylic, and C(sp3)?H bonds alpha to heteroatoms. Elaboration of the products enables the synthesis of a series of versatile building blocks. Control experiments implicate the in situ generation of a tertiary carbon-centered radical species.
- Tian, Ming-Qing,Shen, Zhen-Yao,Zhao, Xuefei,Walsh, Patrick J.,Hu, Xu-Hong
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supporting information
p. 9706 - 9711
(2021/03/19)
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- Synthesis and conformational analysis of poly(phenylacetylene)s with serinol-tethered carbohydrate appendages
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We synthesized phenylacetylenes containing β-lactoside, β-cellobioside, or β-maltoside, and polymerized them to produce the corresponding poly (phenylacetylene)s. In these poly (phenylacetylene)s, the pendent carbohydrates were tethered to the mainchains
- Masubuchi, Kana,Maehata, Masakiyo,Suzuki, Chieko,Matsuoka, Ryoji,Sekiguchi, Maki,Chigira, Naoto,Amano, Yoshitsugu,Inokuchi, Mayu,Li, Qintong,Hasegawa, Teruaki
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- Irreversible Cysteine-Selective Protein Labeling Employing Modular Electrophilic Tetrafluoroethylation Reagents
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Fluoroalkylation reagents based on hypervalent iodine are widely used to transfer fluoroalkyl moieties to various nucleophiles. However, the transferred groups have so far been limited to simple structural motifs. We herein report a reagent featuring a secondary amine that can be converted to amide, sulfonamide, and tertiary amine derivatives in one step. The resulting reagents bear manifold functional groups, many of which would not be compatible with the original synthetic pathway. Exploiting this structural versatility and the known high reactivity toward thiols, the new-generation reagents were used in bioconjugation with an artificial retro-aldolase, containing an exposed cysteine and a reactive catalytic lysine. Whereas commercial reagents based on maleimide and iodoacetamide labeled both sites, the iodanes exclusively modified the cysteine residue. The study thus demonstrates that modular fluoroalkylation reagents can be used as tools for cysteine-selective bioconjugation.
- Václavík, Ji?í,Zschoche, Reinhard,Klimánková, Iveta,Matou?ek, Václav,Beier, Petr,Hilvert, Donald,Togni, Antonio
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supporting information
p. 6490 - 6494
(2017/05/15)
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- Smectic liquid crystals comprising triazole banana shaped achiral molecules: Synthesis and characterization
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A series of novel liquid crystals containing [1,2,3]-triazole ring were synthesized via “click chemistry.” Their mesomorphic properties and photoelectric properties were investigated and the results indicated that most of compounds exhibited SmA over a wide temperature range (about 50°C). The threshold voltage and the response time of the mixture, T4 and LC 50100 were shorten 0.43?V and 71.5?ms with respect to those of LC 50100 respectively.
- Li, Xiaolian,Zhang, Zongying,Liuya
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p. 395 - 404
(2017/05/26)
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- A General Cp*CoIII-Catalyzed Intramolecular C?H Activation Approach for the Efficient Total Syntheses of Aromathecin, Protoberberine, and Tylophora Alkaloids
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Herein, we report a Cp*CoIII-catalyzed C?H activation approach as the key step to create highly valuable isoquinolones and pyridones as building blocks that can readily be applied in the total syntheses of a variety of aromathecin, protoberberine, and tylophora alkaloids. This particular C?H activation/annulation reaction was achieved with several terminal as well as internal alkyne coupling partners delivering a broad scope with excellent functional group tolerance. The synthetic applicability of this protocol reported herein was demonstrated in the total syntheses of two Topo-I-Inhibitors and two 8-oxyprotoberberine cores that can be further elaborated into the tetrahydroprotoberberine and the protoberberine alkaloid core. Moreover these building blocks were also transformed to six different tylophora alkaloids in expedient fashion.
- Lerchen, Andreas,Knecht, Tobias,Koy, Maximilian,Daniliuc, Constantin G.,Glorius, Frank
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supporting information
p. 12149 - 12152
(2017/09/13)
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- Natural-Product-Inspired Aminoepoxybenzoquinones Kill Members of the Gram-Negative Pathogen Salmonella by Attenuating Cellular Stress Response
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Gram-negative bacteria represent a challenging task for antibacterial drug discovery owing to their impermeable cell membrane and restricted uptake of small molecules. We herein describe the synthesis of natural-product-derived epoxycyclohexenones and explore their antibiotic activity against several pathogenic bacteria. A compound with activity against Salmonella Typhimurium was identified, and the target enzymes were unraveled by quantitative chemical proteomics. Importantly, two protein hits were linked to bacterial stress response, and corresponding assays revealed an elevated susceptibility to reactive oxygen species upon compound treatment. The consolidated inhibition of these targets provides a rationale for antibacterial activity and highlights epoxycyclohexenones as natural product scaffolds with suitable properties for killing Gram-negative Salmonella.
- Mandl, Franziska A.,Kirsch, Volker C.,Ugur, Ilke,Kunold, Elena,Vomacka, Jan,Fetzer, Christian,Schneider, Sabine,Richter, Klaus,Fuchs, Thilo M.,Antes, Iris,Sieber, Stephan A.
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p. 14852 - 14857
(2016/11/23)
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- Synthesis of OSW-1 derivatives by site-selective acylation and their biological evaluation
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A strategy to site-selectively monoacylate an antitumor saponin OSW-1 was developed using an organotin reagent to rapidly access its derivatives that are useful as chemical probes. 4″-O-Acylated OSW-1 derivatives bearing a fluorophore, an alkyne tag, or biotin were prepared in good yields and were shown to maintain highly cytotoxic activity.
- Sakurai, Kaori,Takeshita, Tomoya,Hiraizumi, Masato,Yamada, Rika
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supporting information
p. 6318 - 6321
(2015/02/19)
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- Synthesis and characterization of poly(phenylacetylenes) featuring activated ester side groups
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Four monomers based on 4-ethynylbenzoic acid have been synthesized, one of those featuring an activated ester. With the metathesis catalytic system WCl6/Ph4Sn, these acetylenic monomers could successfully be polymerized yielding conjugated polymers with molecular weights of around 10,000 to 15,000 g/mol and molecular weight distributions Mw/M n ≤ 2.1. Also the copolymerization of phenylacetylene or methyl 4-ethynylbenzoate with pentafluorophenyl 4-ethynylbenzoate as reactive unit was conducted. Polymer analogous reactions of the reactive polymers and copolymers with amines have been investigated and it was found that poly(pentafluorophenyl 4-ethynylbenzoate) featured a significant reactivity, such that reactions proceeded quantitatively even with aromatic amines. Moreover the UV-Vis spectra of the activated ester based polymer before and after conversion with aliphatic amines showed a change, indicating an effect on the conjugated backbone of the polymers. Copyright
- Pauly, Anja C.,Theato, Patrick
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p. 211 - 224
(2011/09/16)
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- Controlled and chemoselective reduction of secondary amides
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This communication describes a metal-free methodology involving an efficient and controlled reduction of secondary amides to imines, aldehydes, and amines in good to excellent yields under ambient pressure and temperature. The process includes a chemoselective activation of a secondary amide with triflic anhydride in the presence of 2-fluoropyridine. The electrophilic activated amide can then be reduced to the corresponding iminium using triethylsilane, a cheap, rather inert, and commercially available reagent. Imines can be isolated after a basic workup or readily transformed to the aldehydes following an acidic workup. The amine moiety can be accessed via a sequential reductive amination by the addition of silane and Hantzsch ester hydride in a one-pot reaction. Moreover, this reduction tolerates various functional groups that are usually reactive under reductive conditions and is very selective to secondary amides.
- Pelletier, Guillaume,Bechara, William S.,Charette, Andre B.
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supporting information; experimental part
p. 12817 - 12819
(2010/11/05)
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- Smectic aggregates of sheet-like side-chain liquid crystalline polyacetylenes directly formed during solution polymerization
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We have successfully synthesized two side-chain liquid crystalline polyacetylenes (denoted as P3-5 and P2-5) with the mesogenic units based on a "phenyl-ester-phenyl" motif directly linked to the semirigid polyacetylene backbone in a terminal-on mode without flexible spacer. During the polymerization catalyzed by Rh(nbd)[B(C6H5)4] in toluene, the resultant polymers (or oligomers) automatically precipitate out of the polymerization solution as red solids, which cannot be dissolved in common organic solvents. Wide-angle X-ray diffraction results confirm that the polymer precipitates possess a smectic (or sanidic) structure, suggesting that the molecules without flexible spacers are sheet-like and can stack parallel to each other during polymerization. We in situ monitored the solution polymerization and the aggregation processes using UV-visible and 1H NMR spectroscopy methods. The experimental results indicate that after reaching a critical molecular weight the P3-5 and P2-5 molecules self-aggregate in solution and that the smectic aggregation proceeds during the solution polymerization. An apparent first-order polymerization kinetics can be obtained after the polymerization and aggregation slowed down. The resultant polymers are cis-rich with the main-chain absorption at ~455 nm. This implies that a considerably long effective conjugation length is achieved in the sheet-like cis-rich polyacetylene derivatives.
- Liu, Lu-Mei,Liu, Kai-Peng,Dong, Yu-Ping,Chen, Er-Qiang,Tang, Ben Zhong
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experimental part
p. 6014 - 6023
(2011/10/19)
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- Silica- and polymer-supported platinum(II) polypyridyl complexes: Synthesis and application in photosensitized oxidation of alkenes
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Square-planar polypyridine platinum(II) complexes have been introduced into a silica/polymer matrix by covalent ligand modification. The photophysical properties of the supported matrices are well retained as their model complexes, and the quantum yields for singlet oxygen (1O2) generation are comparable with that of TPP (tetraphenylporphyrin) under similar conditions. A preliminary application in photosensitized oxidation indicates the silica/polymer-supported matrices are promising, which can be reused without loss of reactivity by a simple filtration. Moreover, the polymer-supported matrix exhibits excellent compatibility in various solvents. The Royal Society of Chemistry 2009.
- Feng, Ke,Peng, Ming-Li,Wang, Deng-Hui,Zhang, Li-Ping,Tung, Chen-Ho,Wu, Li-Zhu
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experimental part
p. 9794 - 9799
(2010/03/04)
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- Amino acid-containing polyacetylenes: Synthesis, hydrogen bonding, chirality transcription, and chain helicity of amphiphilic poly(phenylacetylene)s carrying L-leucine pendants
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L-Leucine-phenylacetylene adducts 6 and 14 undergo self-association in concentrated solutions and heterocomplexation with solvent molecules through hydrogen bond formation. The adducts are polymerized by rhodium catalysts into poly(4-ethynylbenzoyl-L-leuc
- Cheuk, Kevin K.L.,Lam, Jacky W.Y.,Chen, Junwu,Lai, Lo Ming,Tang, Ben Zhong
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p. 5947 - 5959
(2007/10/03)
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- Ethynyl and substituted ethynyl-terminated polysulfones
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Ethynyl and substituted ethynyl-terminated polysulfones and a process for preparing the same are disclosed. These polysulfones are thermally cured to induce cross-linking and chain extension, producing a polymer system with improved solvent resistance and
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