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31.
Yuta Tsunoda Katsunori Fukuta Taisuke Imamura Prof. Dr. Ryo Sekiya Dr. Taniyuki Furuyama Prof. Dr. Nagao Kobayashi Prof. Dr. Takeharu Haino 《Angewandte Chemie (International ed. in English)》2014,53(28):7243-7247
Encapsulation of chiral guests in the dissymmetric capsule 1?4 BF4 formed diastereomeric supramolecular complexes G ? 1?4 BF4 ( G : guest). When chiral guests 2 a – q were encapsulated within the dissymmetric space of the self‐assembled capsule 1?4 BF4, circular dichroism (CD) was observed at the absorption bands that are characteristic of the π–π* transition of the bipyridine moiety of the capsule, which suggests that the P and M helicities of the capsule are biased by the chiral guest complexation. The P helicity of diastereomeric complex (S)‐ 2 l ? 1?4 BF4 was determined to be predominant, based on CD exciton coupling theory and DFT calculations. The diastereoselectivity was highly influenced by the ester substituents, such that benzyl ester moieties were good for improving the diastereoselectivity. A diastereomeric excess of 98 % was achieved upon the complexation of 2 j . The relative enthalpic and entropic components for the distereoselectivity were obtained from a van’t Hoff plot. The enthalpic components were linearly correlated with the substituent Hammett parameters (σp+). The electron‐rich benzyl ester moieties generated donor–acceptor π–π stacking interactions with the bipyridine moiety, which resulted in a significant difference in energy between the predominant and subordinate diastereomeric complexes. 相似文献
32.
D3h‐Symmetric Porphyrin‐Based Rigid Macrocyclic Ligands for Multicofacial Multinuclear Complexes in a One‐Nanometer‐Sized Cavity 下载免费PDF全文
Yohei Ohkoda Akane Asaishi Tomoya Namiki Tomoaki Hashimoto Midori Yamada Koichiro Shirai Yuta Katagami Dr. Tomoaki Sugaya Prof. Makoto Tadokoro Prof. Akiharu Satake 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11745-11756
The one‐step synthesis of D3h‐symmetric cyclic porphyrin trimers 1 composed of three 2,2′‐[4,4′‐bis(methoxycarbonyl)]bipyridyl moieties and three porphyrinatozinc moieties was achieved from a nickel‐mediated reductive coupling of meso‐5,15‐bis(6‐chloro‐4‐methoxycarbonylpyrid‐2‐yl)porphyrinatozinc. Although cyclic trimers 1 were obtained as a mixture that included other cyclic and acyclic porphyrin oligomers, an extremely specific separation was observed only for cyclic trimers 1 when using columns of silica gel modified with pyrenylethyl, cyanopropyl, and other groups. Structural analysis of cyclic trimers 1 was carried out by means of NMR spectroscopy and X‐ray crystallography. Treatment of an η3‐allylpalladium complex with a cyclic trimer gave a tris(palladium) complex containing three η3‐allylpalladium groups inside the space, which indicated that the bipyridyl moieties inside the ring could work as bidentate metalloligands. 相似文献
33.
Birendra Babu Adhikari Naoya Hashiguchi Keisuke Ohto Hidetaka Kawakita Katsutoshi Inoue 《Journal of inclusion phenomena and macrocyclic chemistry》2009,65(1-2):121-128
Three different resins namely 1:5 MC-resin, 1:3 MC-resin and 1:1 MC-resin have been synthesized by methylene crosslinking of 2-pyridylcalix[4]arene. Adsorption behavior of these resins towards the metal ions existing in photographic waste was investigated. The resins show absolute efficiency for adsorption of silver ion with no affinity for other coexisting ions. First two resins form 1:1 complex whereas the third one forms 2:1 complex with silver ion. Maximum loading capacity of silver ion on the present resins was found to be 1.15, 1.29 and 0.69 mol kg?1, respectively. Column chromatographic separation of silver ion in presence of excess of sodium ions was also carried out with 1:5 MC-resin. Selective adsorption of silver ions over excess of sodium ions was achieved. 相似文献
34.
The authors have demonstrated the Hf(OTf)4-doped Me3SiCl system-catalyzed aminomethylation of electron-rich aromatic compounds, such as indoles and anilines, with new types of N,O-acetals having a variety of functional groups, such as cyano, ester, bis(trimethylsilyl)amino, diallylamino, and cyclic amino moieties, for the preparation of non-natural aromatic amino acid derivatives. Aminomethylation using an N,O-acetal with a bis(trimethylsilyl)amino group was particularly successful in the direct preparation of an N-unsubstituted α-indolylglycine derivative, which required only a standard aqueous workup. 相似文献
35.
Akiko Hori Yuta Inoue Hidetaka Yuge 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(5):o154-o156
4‐Chloro‐5‐(2‐phenoxyethoxy)phthalonitrile, C16H11ClN2O2, (I), and 4‐chloro‐5‐[2‐(pentafluorophenoxy)ethoxy]phthalonitrile, C16H6ClF5N2O2, (II), show different types of electrostatic interaction. In (I), the phenoxy and phthalonitrile (benzene‐1,2‐dicarbonitrile) moieties are well separated in an open conformation and intermolecular C—H...π interactions are observed in the crystal packing. On the other hand, in (II), the pentafluorophenoxy moiety interacts closely with the Cl atom to form a folded conformation containing an intramolecular halogen–π interaction. 相似文献
36.
Akira Matsumoto Hiroyuki Hamamoto Yuta Miwa Hiroyuki Aota Satoshi Inoue Katsutoshi Yokoyama Yasuo Matoba Michirou Shibano 《Journal of polymer science. Part A, Polymer chemistry》2009,47(11):2871-2881
No difference in the actual gel points was substantially observed among three isomeric diallyl phthalates such as diallyl phthalate (DAP), diallyl isophthalate, and diallyl terephthalate (DAT); this interesting gelation behavior was discussed further in terms of the correlation between gelation and the difference in cyclization modes, and also, the difference in reactivity between the uncyclized and cyclized radicals for cross‐linking. In the present work, we tried to extend the preceding discussion to the polymerization of triallyl trimellitate (TAT) because the molecular structure of TAT is presumed to essentially involve the characteristics of three isomeric diallyl phthalates and, therefore, the enhanced gelation was expected in TAT polymerization. However, no enhancement of gelation was observed. For a full understanding of the gelation in multiallyl cross‐linking polymerization, we explored further the polymerizations of DAP, DAT, and TAT, especially focusing on the characterization of resultant network polymer precursors (NPPs) using SEC‐MALLS‐viscometry providing the correlation of [η] versus Mw of fractionated samples. Notably, the structure of NPP consisting of oligomeric primary polymer chains generated from specific allyl polymerization would become core‐shell type dendritic with the progress of polymerization. The correlation between delayed gelation and decreased reactivity of dendritic NPP for intermolecular cross‐linking is discussed. Conclusively, the reactivity for intermolecular cross‐linking between NPPs decreased with the progress of polymerization leading to a delayed gelation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2871–2881, 2009 相似文献
37.
Peptides with an N-alkoxy or N-aryloxy amino acid at their N-terminus were synthesized and successfully ligated with a peptide thioester by silver ion activation under a slightly acidic condition without requiring protection of the side chain amino groups. The N-methoxy group was easily cleaved by the SmI2 reduction in CH3OH aq. to obtain the desired peptide with a native peptide bond. This method was successfully applied to the synthesis of the human atrial natriuretic peptide showing the efficiency of the novel ligation. 相似文献
38.
Hiroyuki Suga Satoshi Higuchi Daisuke Ishimoto Yuta Hashimoto Teruko Tsuchida Toshihide Baba 《Tetrahedron》2010,66(16):3070-6287
High enantioselectivities (94-96% ee) were obtained for the inverse electron-demand 1,3-dipolar cycloadditions between cyclohexyl vinyl ether and 2-benzopyrylium-4-olate generated via Rh2(OAc)4-catalyzed decomposition of o-methoxycarbonyl-α-diazoacetophenone. The reactions were effectively catalyzed by Eu(OTf)3, Ho(OTf)3, or Gd(OTf)3 complexes (10 mol %) of chiral 2,6-bis[(4S,5S)-4,5-diphenyl-2-oxazolinyl]pyridine. The reactions with the other electron-rich dipolarophiles such as allyl alcohol, 2,3-dihydrofuran, and butyl-tert-butyldimethylsilylketene acetal showed moderate enanantioselectivities (60-73% ee). Good to high enantioselectivities (73-97% ee) were also obtained for the cycloadditions between 3-acyl-2-benzopyrylium-4-olates, generated from methyl 2-(2-diazo-1,3-dioxoalkyl)benzoates and butyl or cyclohexyl vinyl ethers, in the presence of binaphthyldiimine (BINIM)-Ni(II) complexes (10 mol %). Under similar conditions, the reaction between methyl 2-(2-diazo-1,3-dioxohexyl)benzoate and 2,3-dihydrofuran was highly endo-selective, and moderately enantioselective (70% ee). For the BINIM-Ni(II)-catalyzed reactions of cyclohexyl vinyl ether, the use of an epoxyindanone as the 3-acyl-2-benzopyrylium-4-olate precursor revealed that the chiral Lewis acid can function as a catalyst for asymmetric induction. The scope of the cyclic carbonyl ylides was extended to those generated from 1-diazo-2,5-pentanedione derivatives, which were reacted with butyl or TBS vinyl ether and catalyzed using the (4S,5S)-Pybox-4,5-Ph2-Lu(OTf)3 complex to give good levels of asymmetric inductions (75-84% ee). 相似文献
39.
Kenshu Fujiwara Yuta Hirose Hidetoshi Kawai Takanori Suzuki 《Tetrahedron letters》2010,51(32):4263-4546
Armatol F, isolated from the red alga Chondria armata as a polyether triterpene, has a solitary oxepane (A-ring) and a fused tricyclic ether moiety (BCD-ring). The A-ring features a rare cis-relationship between the hydroxy group at the quaternary carbon C6 and the carbon chain at C7. As part of our program toward the total synthesis of armatol F, a new stereoselective method for the construction of the C6 and C7 stereocenters has been developed based on chirality-transferring Ireland-Claisen rearrangement. The A-ring skeleton has also been synthesized from the rearrangement product by a process including ring-closing olefin metathesis. 相似文献
40.
Yuta Marushima Yuri Uchiumi Kenichi Ogu Akiko Hori 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(8):o406-o409
Two C2‐symmetric meso‐alkynylporphyrins, namely 5,15‐bis[(4‐butyl‐2,3,5,6‐tetrafluorophenyl)ethynyl]‐10,20‐dipropylporphyrin, C50H42F8N4, (I), and 5,15‐bis[(4‐butylphenyl)ethynyl]‐10,20‐dipropylporphyrin, C50H50N4, (II), show remarkable π–π stacking that forms columns of porphyrin centers. The tetrafluorophenylene moieties in (I) show intermolecular interactions with each other through the F atoms, forming one‐dimensional ribbons. No significant π–π interactions are observed in the plane of the phenylene and tetrafluorophenylene moieties in either (I) or (II). The molecules of both compounds lie about inversion centers. 相似文献