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91.
Direct Asymmetric Mannich‐Type Reaction of α‐Isocyanoacetates with Ketimines using Cinchona Alkaloid/Copper(II) Catalysts 下载免费PDF全文
Masashi Hayashi Masaru Iwanaga Noriyuki Shiomi Dr. Daisuke Nakane Prof. Dr. Hideki Masuda Prof. Dr. Shuichi Nakamura 《Angewandte Chemie (International ed. in English)》2014,53(32):8411-8415
The enantioselective direct Mannich‐type reaction of ketimines with α‐isocyanoacetates has been developed. Excellent yields and enantioselectivity were observed for the reaction of various ketimines and α‐isocyanoacetates using cinchona alkaloid/Cu(OTf)2 and a base. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts. This process offers an efficient route for the synthesis of α,β‐diamino acids. 相似文献
92.
Total Synthesis of the Antibiotic Kendomycin: A Macrocyclization Using the Tsuji–Trost Etherification 下载免费PDF全文
Dr. Tetsuya Sengoku Dr. Shu Xu Kenji Ogura Yoshinori Emori Kenji Kitada Prof. Dr. Daisuke Uemura Prof. Dr. Hirokazu Arimoto 《Angewandte Chemie (International ed. in English)》2014,53(16):4213-4216
A highly stereocontrolled, convergent total synthesis of kendomycin [(?)‐TAN2162], an ansa‐macrocyclic antibiotic, is reported. The key of the strategy is an unprecedented Tsuji–Trost macrocyclic etherification, followed by a transannular Claisen rearrangement to construct the 18‐membered carbocyclic framework. The oxa‐six‐ and five‐membered rings were also stereoselectively constructed respectively by a cascade oxidative cyclization at an unfunctionalized benzylic position and using a one‐pot epoxidation/5‐exo‐tet epoxide opening. 相似文献
93.
Rational Design and Identification of a Non‐Peptidic Aggregation Inhibitor of Amyloid‐β Based on a Pharmacophore Motif Obtained from cyclo[‐Lys‐Leu‐Val‐Phe‐Phe‐] 下载免费PDF全文
Tadamasa Arai Takushi Araya Dr. Daisuke Sasaki Dr. Atsuhiko Taniguchi Dr. Takeshi Sato Dr. Youhei Sohma Prof. Motomu Kanai 《Angewandte Chemie (International ed. in English)》2014,53(31):8236-8239
Inhibition of pathogenic protein aggregation may be an important and straightforward therapeutic strategy for curing amyloid diseases. Small‐molecule aggregation inhibitors of Alzheimer’s amyloid‐β (Aβ) are extremely scarce, however, and are mainly restricted to dye‐ and polyphenol‐type compounds that lack drug‐likeness. Based on the structure‐activity relationship of cyclic Aβ16–20 (cyclo‐[KLVFF]), we identified unique pharmacophore motifs comprising side‐chains of Leu2, Val3, Phe4, and Phe5 residues without involvement of the backbone amide bonds to inhibit Aβ aggregation. This finding allowed us to design non‐peptidic, small‐molecule aggregation inhibitors that possess potent activity. These molecules are the first successful non‐peptidic, small‐molecule aggregation inhibitors of amyloids based on rational molecular design. 相似文献
94.
Akio Urushima Dr. Daisuke Taura Makoto Tanaka Naomichi Horimoto Dr. Junki Tanabe Dr. Naoki Ousaka Prof. Tadashi Mori Prof. Eiji Yashima 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7548-7556
A novel 2,6-anthrylene-linked bis(m-terphenylcarboxylic acid) strand ( 1 ) self-associates into a racemic double-helix. In the presence of chiral mono- and diamines, either a right- or left-handed double-helix was predominantly induced by chiral amines sandwiched between the carboxylic acid strands with accompanying stacking of the two prochiral anthracene linker units in an enantiotopic face-selective way, as revealed by circular dichroism and NMR spectral analyses. The photoirradiation of the optically active double helices complexed with chiral amines proceeded in a diastereo- (anti or syn) and enantiodifferentiating way to afford the chiral anti-photodimer with up to 98 % enantiomeric excess when (R)-phenylethylamine was used as a chiral double-helix inducer. The resulting optically active anti-photodimer can recognize the chirality of amines and diastereoselectively complex with chiral amines. 相似文献
95.
Daisuke Saito Dr. Tomohiro Ogawa Dr. Masaki Yoshida Junichi Takayama Dr. Satoshi Hiura Prof. Dr. Akihiro Murayama Dr. Atsushi Kobayashi Prof. Dr. Masako Kato 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18882-18889
A series of assembled PtII complexes comprising N-heterocyclic carbene and cyanide ligands was constructed using different substituent groups, [Pt(CN)2(R-impy)] (R-impyH+=1-alkyl-3-(2-pyridyl)-1H-imidazolium, R=Me ( Pt-Me ), Et ( Pt-Et ), iPr ( Pt- i Pr ), and tBu ( Pt- t Bu )). All the complexes exhibited highly efficient photoluminescence with an emission quantum yield of 0.51–0.81 in the solid state at room temperature, originating from the triplet metal-metal-to-ligand charge transfer (3MMLCT) state. Their emission colors cover the entire visible region from red for Pt-Me to blue for Pt- t Bu . Importantly, Pt- t Bu is the first example that exhibits blue 3MMLCT emission. The 3MMLCT emission was proved and characterized based on the temperature dependences of the crystal structures and emission properties. The wide-range color tuning of luminescence using the 3MMLCT emission presents a new strategy of superfine control of the emission color. 相似文献
96.
Dr. Soichiro Nakatsuka Yusuke Watanabe Yoshinobu Kamakura Prof. Satoshi Horike Prof. Daisuke Tanaka Prof. Takuji Hatakeyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(4):1451-1455
A triphosphaazatriangulene (H3L) was synthesized through an intramolecular triple phospha-Friedel–Crafts reaction. The H3L triangulene contains three phosphinate groups and an extended π-conjugated framework, which enables the stimuli-responsive reversible transformation of [Cu(HL)(DMSO)⋅(MeOH)]n, a 3D-MOF that exhibits reversible sorption characteristics, into (H3L⋅0.5 [Cu2(OH)4⋅6 H2O] ⋅4 H2O), a 1D-columnar assembled proton-conducting material. The hydrophilic nature of the latter resulted in a proton conductivity of 5.5×10−3 S cm−1 at 95 % relative humidity and 60 °C. 相似文献
97.
Yukiko Moriizumi Hajime Fukuda Seiya Tanaka Daisuke Tanaka Kazukiyo Nagai 《Journal of polymer science. Part A, Polymer chemistry》2020,58(18):2586-2602
This study aimed to determine the solubility and temperature dependence of methanol and ethanol vapor caused by the difference in the substituents of polyhedral oligomeric silsesquioxane (POSS)-containing polymethacrylate membranes and the spacer length between the backbone and POSS backbone. Vapor sorption of methanol and ethanol was measured at 25°C, 35°C, and 45°C for three kinds of POSS-containing polymer membranes, namely, poly(methacryl isobutyl POSS), poly(methacrylate isobutyl POSS), and poly(methacryl phenyl POSS). The primary structures of the three POSS-containing polymer chains were columnar. The solubility of alcohol vapor on the POSS-containing polymer membranes followed the mechanism of solid adsorption and not the general dissolution diffusion. The sorption amount at all three temperatures was related to the surface area of the cylindrical primary structure and the solid adsorption property of the alcohol molecule of the POSS substituent. The sorption amount increased because of the large surface area and adsorption property of alcohol molecules. Although a typical glassy polymer shows exothermic mixing and a rubbery polymer displays endothermic mixing, the sample with the POSS substituent of isobutyl group exhibited an unusual behavior of endothermic mixing despite being a glassy polymer. 相似文献
98.
Ayuko Tsuruoka Akira Takahashi Daisuke Aoki Hideyuki Otsuka 《Angewandte Chemie (International ed. in English)》2020,59(11):4294-4298
Crosslinked polymers (CLPs) exhibit exceptional mechanical properties as well as good chemical and solvent resistance. However, their reprocessing, recycling, and modification remain difficult. One promising approach to overcome this limitation is to introduce dynamic covalent bonds that enable chain‐exchange reactions and network‐structure rearrangements in identical polymer networks (A–A fusion), resulting in self‐healing and reprocessing properties. Reported here is the fusion of two distinct polymer networks (A–B fusion) by the dynamic behavior of bis(2,2,6,6‐tetramethylpiperidin‐1‐yl)disulfide (BiTEMPS) at the interface between different CLPs. The appearance, swelling behavior, and mechanical properties of the fused samples indicate exchange reactions of the BiTEMPS units and the formation of topological bonds at the interface, commensurate with the generation of a CLP that exhibits tunable properties. 相似文献
99.
100.
Akio Urushima Daisuke Taura Makoto Tanaka Naomichi Horimoto Junki Tanabe Naoki Ousaka Tadashi Mori Eiji Yashima 《Angewandte Chemie (International ed. in English)》2020,59(19):7478-7486
A novel 2,6‐anthrylene‐linked bis(m‐terphenylcarboxylic acid) strand ( 1 ) self‐associates into a racemic double‐helix. In the presence of chiral mono‐ and diamines, either a right‐ or left‐handed double‐helix was predominantly induced by chiral amines sandwiched between the carboxylic acid strands with accompanying stacking of the two prochiral anthracene linker units in an enantiotopic face‐selective way, as revealed by circular dichroism and NMR spectral analyses. The photoirradiation of the optically active double helices complexed with chiral amines proceeded in a diastereo‐ (anti or syn) and enantiodifferentiating way to afford the chiral anti‐photodimer with up to 98 % enantiomeric excess when (R)‐phenylethylamine was used as a chiral double‐helix inducer. The resulting optically active anti‐photodimer can recognize the chirality of amines and diastereoselectively complex with chiral amines. 相似文献