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Ishida Y Kai Y Kato SY Misawa A Amano S Matsuoka Y Saigo K 《Angewandte Chemie (International ed. in English)》2008,47(43):8241-8245
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Masato Matsugi Misaki Suganuma Shoko Yoshida Shohei Hasebe Yoko Kunda Kotaro Hagihara Sayaka Oka 《Tetrahedron letters》2008,49(46):6573-6574
A convenient methodology for the separation of a fluorous by-product using fluorous chemistry is described. A Mukaiyama coupling reagent bearing a medium fluorous tag, between 40% and 60% fluorine by weight, can be effectively separated from non-fluorous components by increasing the water content of the crude reaction mixture and subsequent filtration. Additional fluorous solid phase extraction is not necessary. 相似文献
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We have observed the generation of sumanenylidene ( 2 ), a divalent, neutral‐carbon species at the benzylic position of sumanene ( 1 ). We also clarified both experimentally and theoretically that the ground state of compound 2 was a triplet state and that its singlet–triplet energy gap (ΔEST) was similar to that in fluorenylidene. The curved structure of compound 2 led to slightly better spin delocalization over the two adjacent aromatic rings than in planar systems, because of the unpaired spins on the σ and π orbitals. Synthetic application of the carbene precursor, diazosumanene ( 5 ), with a variety of thiocarbonyl compounds revealed its utility for the preparation of tetrasubstituted alkene compounds (e.g., that contain a strongly electron‐donating unit) that are directly conjugated to the sumanene ( 1 ) moiety. 相似文献
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Sayaka Yoshiwaka Kosuke Sasagawa Keiichi Noguchi Noriyuki Yonezawa Akiko Okamoto 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1096-1100
The title molecule, C40H32O6, possesses crystallographically imposed twofold symmetry, with the central two C atoms of the naphthalene unit sited on the rotation axis. The two 4‐phenoxybenzoyl groups in the molecule are twisted away from the attached naphthalene unit, with a torsion angle of 66.76 (15)° between the naphthalene unit and the carbonyl group (C—C—C=O), and are oriented in mutually opposing directions (anti orientation). There is an apparent difference in the conformations of the 4‐phenoxybenzoyl groups at the 1‐ and 8‐positions of the naphthalene ring between the title molecule and its methoxy‐bearing homologue [Hijikata et al. (2010). Acta Cryst. E 66 , o2902–o2903]. Whilst the 4‐phenoxybenzoyl groups in 2,7‐diisopropoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene [Yoshiwaka et al. (2013). Acta Cryst. E 69 , o242] are situated in the same anti orientation as the title molecule, those of 2,7‐dimethoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene are oriented in the same direction with respect to the naphthalene ring system, i.e. in a syn orientation. 相似文献
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Hiroaki Sato Sayaka Nakamura Kanae Teramoto Takafumi Sato 《Journal of the American Society for Mass Spectrometry》2014,25(8):1346-1355
High-resolution mass spectrometry (HRMS) continues to play an important role in the compositional characterization of larger organic molecules. In the field of polymer characterization, however, the application of HRMS has made only slow progress because of lower compatibility between matrix-assisted laser desorption/ionization (MALDI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). In this study, a newly developed type of MALDI high-resolution time-of-flight mass spectrometry (TOFMS) with a spiral ion trajectory (MALDI spiral-TOFMS) was applied to the structural and compositional characterization of polymers. To create a graphical distribution of polymer components on a two-dimensional plot converted from complex mass spectra, we adopted a slightly modified Kendrick mass defect (KMD) analysis based on accurate masses determined using spiral-TOFMS. By setting the Kendrick mass scale based on the mass of the repeating units of a given polymer, components with common repeat units lined up in the horizontal direction on the KMD plot, whereas those components with different structures were shifted vertically. This combination of MALDI spiral-TOFMS measurement and KMD analysis enabled the successful discrimination of the polymer components in a blend of poly(alkylene oxide)s, the compositional analysis of poly(ethylene oxide)/poly(propylene oxide) block copolymers, and profiling of the end-group distribution of poly(ε-caprolactone)s synthesized under different conditions.
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An Imidazoline–Aminophenol (IAP) Nickel Catalyst: Structure and Catalytic Activity in the Enantioselective 1,4‐Addition of 3′‐Indolyl‐3‐Oxindoles to Nitroethylene
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Atsuko Awata Makiko Wasai Prof. Dr. Hyuma Masu Sayaka Kado Prof. Dr. Takayoshi Arai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2470-2477
The structure of a nickel complex of imidazoline–aminophenol (IAP) prepared from IAP with Ni(OAc)2 was elucidated as cis‐bis(imidazolineaminophenoxide) [Ni(IAP)2]. The [Ni(IAP)2] complex smoothly promoted catalytic asymmetric 1,4‐addition of 3′‐indolyl‐3‐oxindole to nitroethylene to provide chiral mixed 3,3′‐bisindoles with high enantioselectivities. Mechanistic studies using ESI‐MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)2] to generate the Ni–enolate of 3′‐indolyl‐3‐oxindole. From the optically active 3,3′‐mixed indole adduct, biologically important 3′‐indolyl‐3‐pyrrolidinoindoline was successfully synthesized in a three‐step reaction sequence. 相似文献