1738-76-7Relevant articles and documents
Rhenium complexes of bidentate, bis-bidentate and tridentate N-heterocyclic carbene ligands
Chan, Chung Ying,Barnard, Peter J.
, p. 19126 - 19140 (2015)
A series of eight Rhenium(i)-N-heterocyclic carbene (NHC) complexes of the general form [ReCl(CO)3(C^C)] (where C^C is a bis(NHC) bidentate ligand), [ReCl(CO)3(C^C)]2 (where C^C is a bis-bidentate tetra-NHC ligand) and [Re(CO)3(C^N^C)]+[X]- (where C^N^C is a bis(NHC)-amine ligand and the counter ion X is either the ReO4- or PF6-) have been synthesised using a Ag2O transmetallation protocol. The novel precursor imidazolium salts and Re(i) complexes were characterized by elemental analysis, 1H and 13C NMR spectroscopy and the molecular structures for two imidazolium salt and six Re(i) complexes were determined by single crystal X-ray diffraction. These NHC ligand systems are of interest for possible applications in the development of Tc-99m or Re-186/188 radiopharmaceuticals and as such the stability of two complexes of the form [ReCl(CO)3(C^C)] and [Re(CO)3(C^N^C)][ReO4] were evaluated in ligand challenge experiments using the metal binding amino acids l-histidine or l-cysteine. These studies showed that the former was unstable, with the chloride ligand being replaced by either cysteine or histidine, while no evidence for transchelation was observed for the latter suggesting that bis(NHC)-amine ligands of this type may be suitable for biological applications.
Tightly Bound Double-Caged [60]Fullerene Derivatives with Enhanced Solubility: Structural Features and Application in Solar Cells
Brotsman, Victor A.,Ioutsi, Vitaliy A.,Rybalchenko, Alexey V.,Markov, Vitaliy Yu.,Belov, Nikita M.,Lukonina, Natalia S.,Troyanov, Sergey I.,Ioffe, Ilya N.,Trukhanov, Vasiliy A.,Galimova, Galina K.,Mannanov, Artur A.,Zubov, Dmitry N.,Kemnitz, Erhard,Sidorov, Lev N.,Magdesieva, Tatiana V.,Paraschuk, Dmitry Yu.,Goryunkov, Alexey A.
, p. 1075 - 1086 (2017)
A series of novel highly soluble double-caged [60]fullerene derivatives were prepared by means of lithium-salt-assisted [2+3] cycloaddition. The bispheric molecules feature rigid linking of the fullerene spheres through a four-membered cycle and a pyrrolizidine bridge with an ester function CO2R (R=n-decyl, n-octadecyl, benzyl, and n-butyl; compounds 1 a–d, respectively), as demonstrated by NMR spectroscopy and X-ray diffraction. Cyclic voltammetry studies revealed three closely overlapping pairs of reversible peaks owing to consecutive one-electron reductions of fullerene cages, as well as an irreversible oxidation peak attributed to abstraction of an electron from the nitrogen lone-electron pair. Owing to charge delocalization over both carbon cages, compounds 1 a–d are characterized by upshifted energies of frontier molecular orbitals, a narrowed bandgap, and reduced electron-transfer reorganization energy relative to pristine C60. Neat thin films of the n-decyl compound 1 a demonstrated electron mobility of (1.3±0.4)×10?3 cm2 V?1 s?1, which was comparable to phenyl-C61-butyric acid methyl ester (PCBM) and thus potentially advantageous for organic solar cells (OSC). Application of 1 in OSC allowed a twofold increase in the power conversion efficiencies of as-cast poly(3-hexylthiophene-2,5-diyl) (P3HT)/1 devices relative to the as-cast P3HT/PCBM ones. This is attributed to the good solubility of 1 and their enhanced charge-transport properties — both intramolecular, owing to tightly linked fullerene cages, and intermolecular, owing to the large number of close contacts between the neighboring double-caged molecules. Test P3HT/1 OSCs demonstrated power-conversion efficiencies up to 2.6 % (1 a). Surprisingly low optimal content of double-caged fullerene acceptor 1 in the photoactive layer (≈30 wt %) favored better light harvesting and carrier transport owing to the greater content of P3HT and its higher degree of crystallinity.
Synthesis of novel all-cis-functionalized cyclopropane template-assembled collagen models
Yamazaki,Sakamoto,Suzuri,Doi,Nakazawa,Kobayashi
, p. 1870 - 1875 (2001)
An all-cis-functionalized cyclopropane template to connect the three peptide chains in a collagen model is designed. Stereoselective synthesis of cyclopropane-assembled collagen-model 2b with the minimum unit of Gly-Pro-Pro is based on a novel 1-seleno-2-silylethene [2 + 1] cycloaddition strategy. Reaction of the 1-seleno-2-silylethene 4 with triester-substituted olefin 5 in the presence of ZnI2 gives [2 + 1] cycloadduct 6 stereoselectively. Cyclopropane 6 is selectively transformed into triol 10 in four steps. The reaction of 10 and three equivalents ofN-Boc-Pro-Pro-Gly-OH in the presence of WSC-DMAP and subsequent deprotection with TFA gives 2b.
Discovery of Potent, Reversible, and Competitive Cruzain Inhibitors with Trypanocidal Activity: A Structure-Based Drug Design Approach
De Souza, Mariana L.,De Oliveira Rezende Junior, Celso,Ferreira, Rafaela S.,Espinoza Chávez, Rocio Marisol,Ferreira, Leonardo L. G.,Slafer, Brian W.,Magalh?es, Luma G.,Krogh, Renata,Oliva, Glaucius,Cruz, Fabio Cardoso,Dias, Luiz Carlos,Andricopulo, Adriano D.
, p. 1028 - 1041 (2019/12/27)
A virtual screening conducted with nearly 4?000?000 compounds from lead-like and fragment-like subsets enabled the identification of a small-molecule inhibitor (1) of the Trypanosoma cruzi cruzain enzyme, a validated drug target for Chagas disease. Subsequent comprehensive structure-based drug design and structure-activity relationship studies led to the discovery of carbamoyl imidazoles as potent, reversible, and competitive cruzain inhibitors. The most potent carbamoyl imidazole inhibitor (45) exhibited high affinity with a Ki value of 20 nM, presenting both in vitro and in vivo activity against T. cruzi. Furthermore, the most promising compounds reduced parasite burden in vivo and showed no toxicity at a dose of 100 mg/kg. These carbamoyl imidazoles are structurally attractive, nonpeptidic, and easy to prepare and synthetically modify. Finally, these results further advance our understanding of the noncovalent mode of inhibition of this pharmaceutically relevant enzyme, building strong foundations for drug discovery efforts.
Double-caged fullerene acceptors: Effect of alkyl chain length on photovoltaic performance
Brotsman, Victor A.,Rybalchenko, Alexey V.,Zubov, Dmitry N.,Paraschuk, Dmitry Yu.,Goryunkov, Alexey A.
supporting information, p. 3278 - 3285 (2019/03/19)
We report the synthesis and spectroscopic and electrochemical characterization of the benzyl, C4, C6, C8, C9, C10, and C18n-alkyl esters of double-caged fullerene compounds (dFR). Counterintuitively, their solubility depends nonmonotonically on the alkyl chain length with a minimum at n-octyl. The series of dFR compounds were tested in organic solar cells (OSCs) as an acceptor material blended with the poly(3-hexylthiophene-2,5-diyl) (P3HT) donor. With the exception of the n-octadecyl derivative, the performance of the P3HT/dFR solar cells correlates with the solubility of the dFR component, likely due to the improved bulk heterojunction morphology and its favorable effect on JSCvia lower series resistance. A peak PCE of 3.0% was found for the n-nonyl compound, thus exceeding other known fullerene oligomers with fused fullerene cages or cross-linked fullerene dimers. The poor performance of compounds with too long alkyl chains like n-octadecyl reflects larger series resistance that results from a higher degree of phase segregation.
Synthetic Marine Sponge Collagen by Late-Stage Dihydroxylation
Priem, Christoph,Geyer, Armin
supporting information, p. 162 - 165 (2018/01/17)
Based on the observation that an increased substrate size is paralleled by an enhanced diastereoselectivity, a late-stage dihydroxylation protocol toward the 21mer CMP (collagen model peptide) Ac-(Pro-Hyp-Gly)3-Pro-Dyp-Gly-(Pro-Hyp-Gly)3-NH2 is presented. C3 and C4 hydroxylation have a converse effect on the triple-helical stability of collagen. Their combined influence on the melting temperature was studied by NMR spectroscopy.
Preparation method of glycine benzyl ester toluene-4-sulfonate
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Paragraph 0020; 0021, (2016/11/17)
The invention discloses a preparation method of glycine benzyl ester toluene-4-sulfonate. The preparation method comprises the steps of carrying out heating reflux after mixing p-toluene sulfonic acid monohydrate or p-toluene sulfonic acid tetrahydrate with methyl benzene, and separating generated water during reflux until no water is generated; then adding glycine and benzyl alcohol in a feed liquid, continuously carrying out heating reflux until no water is generated, separating the generated water, and continuously carrying out the reflux for 1.5 to 2.5 hours; then cooling, stirring and crystallizing, and filtering, washing and drying a crystal substance, thus obtaining a product. According to the preparation method disclosed by the invention, the water contained in p-toluene sulfonic acid is firstly separated, then the generated water can be continuously separated during continuous reaction processes by adding the glycine and the benzyl alcohol, and the reaction is enabled to proceed quickly, so that the reaction time is shortened, and the working efficiency is increased; meanwhile, the yield is increased, and the product quality is also increased.
C-F Activation in Perfluorinated Arenes with Isonitriles under UV-Light Irradiation
Dewanji, Abhishek,Mück-Lichtenfeld, Christian,Bergander, Klaus,Daniliuc, Constantin G.,Studer, Armido
supporting information, p. 12295 - 12298 (2015/08/25)
Due to the great value of fluorinated arenes in agrochemistry, medicinal chemistry and materials science, development of methods for preparation of fluorinated arenes is of high importance. They can be either accessed by arene fluorination or by partial arene defluorination. However, the carbon-fluorine bond belongs to the strongest σ-bonds, which renders C-F activation highly challenging. Here it is shown that aryl and alkyl isonitriles efficiently activate the strong C-F bond in perfluoroarenes by simple UV irradiation under mild conditions. Reactions proceed by formal direct insertion of the isonitrile into the C-F bond without any transition metal. Activation occurs at arene C-F bonds whereas aliphatic C-F bonds remain unreacted. For selected perfluoroarenes C-F activation occurs with high regioselectivity and resulting imidoyl fluorides are transformed into other valuable compounds. Theoretical studies give insights into the reaction mechanism.
A cation-directed two-component cascade approach to enantioenriched pyrroloindolines
Wolstenhulme, Jamie R.,Cavell, Alex,Grediak, Matija,Driver, Russell W.,Smith, Martin D.
supporting information, p. 13585 - 13588 (2015/02/19)
A cascade approach to complex pyrroloindolines bearing all-carbon quaternary stereocentres has been developed. This two-component process uses a chiral ammonium salt to control diastereo- and enantioselectivity in the addition of isocyanides to functionalized alkenes to afford pyrroloindolines with up to three stereocentres. A mechanistic proposal involving intramolecular hydrogen bond activation of the isocyanide is described.
Synthesis of NO-NSAID dendritic prodrugs via Passerini reaction:new approach to the design of dendrimer-drug conjugates
Du, Zuyin,Yanhui, Lu,Dai, Xuedong,Zhang-Negrerie, Daisy,Gao, Qingzhi
, p. 181 - 185 (2013/07/05)
We report the synthesis of a novel class of dendritic prodrugs via Passerini reaction in one pot. Such dendrimers feature a simultaneous attachment of a conventional non-steroidal anti-inflammatory drug (NSAID) (such as ibuprofen and aspirin) and a nitric oxide (NO)-releasing moiety (such as an organic nitrate) onto their surface, and are therefore regarded as new drug delivery systems for NO-releasing NSAIDs (NO-NSAIDs).
