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61.
Diastereo- and Enantiocontrolled Synthesis of (–)-Allosedamine via Cycloaddition of a Chiral Nitrone
The piperidine alkaloid (–)-allosedamine ( 1 ) has been synthesized, in 21% overall yield, in nine steps starting from the formyl-ester 4 . The synthesis features the reaction cascade 7 → 3 → 2 , involving asymmetric electrophilic enolate hydroxyamination, hydroxylamine/aldehyde condensation, and nitrone/styrene cycloaddition, as well as the reductive N/O cleavage-decyanation 12 → 1 . 相似文献
62.
Simultaneous Modulation of Magnetic and Dielectric Transition via Spin‐Crossover‐Tuned Spin Arrangement and Charge Distribution 下载免费PDF全文
Dr. Hui Zheng Dr. Yin‐Shan Meng Guang‐Li Zhou Prof. Chun‐Ying Duan Prof. Osamu Sato Prof. Shinya Hayami Prof. Yi Luo Prof. Tao Liu 《Angewandte Chemie (International ed. in English)》2018,57(28):8468-8472
Magnetic and dielectric properties have been tuned simultaneously by external stimuli with rapid and sensitive response, which is crucial to monitor the magnetic state via capacitive measurement. Herein, positive charged FeII ions were linked via negative charged [(Tp)FeIII(CN)3]? (Tp=hydrotris(pyrazolyl)borate) units to form a neutral chain. The spin‐crossover (SCO) on FeII sites could be sensitively triggered via thermal treatment, light irradiation, and pressure. SCO switched the spin state of the FeII ions and antiferromagnetic interactions between FeIII and FeII ions, resulting in significant change in magnetization. Moreover, SCO induced rotation of negative charged [(Tp)FeIII(CN)3]? units, generating dielectric anomaly due to geometric change of charges distribution. This work provides a rational way to manipulate simultaneous variations in magnetic and dielectric properties utilizing SCO as an actuator to tune spin arrangement, magnetic coupling, and charge distribution. 相似文献
63.
Andriani Furoida Misato Daitani Kyohei Hisano Osamu Tsutsumi 《Molecules (Basel, Switzerland)》2021,26(23)
Gold(I) complexes, enabling to form linear coordination geometry, are promising materials for manifesting both aggregation-induced emission (AIE) behavior due to strong intermolecular Au–Au (aurophilic) interactions and liquid crystalline (LC) nature depending on molecular geometry. In this study, we synthesized several gold(I) complexes with rod-like molecular skeletons where we employed a mesogenic biphenylethynyl ligand and an isocyanide ligand with flexible alkoxyl or alkyl chains. The AIE behavior and LC nature were investigated experimentally and computationally. All synthesized gold(I) complexes exhibited AIE properties and, in crystal, room-temperature phosphorescence (RTP) with a relatively high quantum yields of greater than 23% even in air. We have demonstrated that such strong RTP are drastically changed depending on the crystal-size and/or crystal growth process that changes quality of crystals as well as the aggregate structure, of e.g., Au–Au distance. Moreover, the complex with longer flexible chains showed LC nature where RTP can be observed. We expect these rod-like gold(I) complexes to have great potential in AIE-active LC phosphorescent applications such as linearly/circularly polarizing phosphorescence materials. 相似文献
64.
65.
Pentacyanoferrate-bound poly(1-vinylimidazole) (PVI[Fe(CN)5]) was selected as a mediator for amperometric creatinine determination based on the reductive H2O2 detection. Creatinine amidohydrolase (CNH), creatine amidohydrolase (CRH), sarcosine oxidase (SOD), peroxidase (POD), and PVI[Fe(CN)5] were crosslinked with poly(ethylene glycol) diglycidyl ether (PEGDGE) on a glassy carbon (GC) electrode for a creatinine biosensor fabrication. Reduction current was monitored at −0.1 V in the presence of creatinine and O2. It is revealed that PVI[Fe(CN)5] is suitable as a mediator for a bioelectrocatalytic reaction of POD, since PVI[Fe(CN)5] neither reacts with reactants nor works as an electron acceptor of SOD. The amounts of PVI[Fe(CN)5], PEGDGE, and enzymes were optimized toward creatinine detection. Nafion as a protecting film successfully prevented the enzyme layer from interferences. The detection limit and linear range in creatinine determination were 12 μM and 12–500 μM (R2 = 0.993), respectively, and the sensitivity was 11 mA cm−2 M−1, which is applicable for urine creatinine tests. The results of the creatinine determination for four urine samples measured with this proposed method were compared with Jaffe method, and a good correlation was obtained between the results. 相似文献
66.
Osamu Sangen Singo Masuda Hidehiko Nakano Kazusige Yamana Kenichi Sasaki Naoki Ikeda 《Journal of polymer science. Part A, Polymer chemistry》1992,30(6):1171-1175
A new synthetic pathway of A–B–A tri-block copolyether which is composed of a hydrophilic poly(oxyethylene) unit as an A part and a hydrophobic poly(oxy-2-methyl-trimethylene) unit as a B part is proposed. Telechelic α-tosyl-ω-tosyloxypoly(oxy-2-methyl-trimethylene) derived from tosylation of poly(oxy-2-methyl-trimethylene glycol) (PMTG) was allowed to react with poly(ethylene glycol) (PEG) in the presence of sodium hydroxide. Tg of the resulting A–B–A tri-block copolyether (PEMG) (M?n = 1600) was ?72°C and its specific gravity [D415] was 1.055. 相似文献
67.
Mark P. WattersonAlison A. Edwards John A. LeachMartin D. Smith Osamu IchiharaGeorge W.J. Fleet 《Tetrahedron letters》2003,44(31):5853-5857
Efficient syntheses of all diastereomers of methyl 2,5-anhydro-3-deoxy-hexonate from mannono- or gulono-lactones provide precursors for C-nucleosides of 2-deoxyribose and for THF-templated γ- and δ-amino acids. 相似文献
68.
Aramburo LR Karwacki L Cubillas P Asahina S de Winter DA Drury MR Buurmans IL Stavitski E Mores D Daturi M Bazin P Dumas P Thibault-Starzyk F Post JA Anderson MW Terasaki O Weckhuysen BM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(49):13773-13781
A combination of atomic force microscopy (AFM), high‐resolution scanning electron microscopy (HR‐SEM), focused‐ion‐beam scanning electron microscopy (FIB‐SEM), X‐ray photoelectron spectroscopy (XPS), confocal fluorescence microscopy (CFM), and UV/Vis and synchrotron‐based IR microspectroscopy was used to investigate the dealumination processes of zeolite ZSM‐5 at the individual crystal level. It was shown that steaming has a significant impact on the porosity, acidity, and reactivity of the zeolite materials. The catalytic performance, tested by the styrene oligomerization and methanol‐to‐olefin reactions, led to the conclusion that mild steaming conditions resulted in greatly enhanced acidity and reactivity of dealuminated zeolite ZSM‐5. Interestingly, only residual surface mesoporosity was generated in the mildly steamed ZSM‐5 zeolite, leading to rapid crystal coloration and coking upon catalytic testing and indicating an enhanced deactivation of the zeolites. In contrast, harsh steaming conditions generated 5–50 nm mesopores, extensively improving the accessibility of the zeolites. However, severe dealumination decreased the strength of the Brønsted acid sites, causing a depletion of the overall acidity, which resulted in a major drop in catalytic activity. 相似文献
69.
Fluorous reverse-phase silica gel (FRPSG)-supported Lewis acids which have fluorous ligands acted as effective catalysts of Baeyer-Villiger and Diels-Alder reactions in water. Direct esterification of carboxylic acid with alcohol in organic media was also catalyzed. The FRPSG-supported Lewis acids could be recycled by simple filtration after the reaction. 相似文献
70.
Yasuhara T Nishimura K Yamashita M Fukuyama N Yamada K Muraoka O Tomioka K 《Organic letters》2003,5(7):1123-1126
[reaction: see text] An omega-nitro-alpha,beta,psi,omega-unsaturated ester underwent a chemoselective conjugate addition of a nitroolefin moiety with aryllithium to produce a psi-aryl-omega-nitro-alpha,beta-unsaturated ester, which was then stereoselectively cyclized by intramolecular nitro-Michael reaction giving a functionalized cyclohexane applicable to the total synthesis of (+/-)-alpha- and beta-lycoranes. 相似文献