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171.
172.
[reaction: see text] Carbamates or sulfonamides have proven to regioselectively attack 2-propynyl-allyl hybrid cations, generated by the action of TMSOTf on 4-(trimethylsioxy)hex-5-en-2-ynoates, to afford conjugated 6-aminohex-4-en-2-ynoates in which an intramolecular amino-Michael reaction took place, leading to pyrrole frameworks. In particular, the sulfonamides gave 1-sulfonylpyrroles in one pot. 相似文献
173.
Sou Kikuchi Kayo Okada Yuko Cho Shinichiro Yoshida Eunsang Kwon Mari Yotsu-Yamashita Keiichi Konoki 《Tetrahedron》2018,74(27):3742-3747
Marine sponge Halichondria okadai is a source of numerous toxic secondary metabolites, which are considered as products of the symbiotic species associated with the sponge. In this study, we tested 720 culture conditions and purified 48 sponge-associated microbes. The ethyl acetate extract from the liquid culture of each species was tested for cytotoxicity, hemolytic activity, and brine shrimp lethal activity. Lysiformine (1) was isolated from Lysinibacillus fusiformis and its structure was determined by HRMS and NMR. 相似文献
174.
Cover Picture: Sequential SNAr Reaction/Suzuki–Miyaura Coupling/C−H Direct Arylations Approach for the Rapid Synthesis of Tetraaryl‐Substituted Pyrazoles (Chem. Asian J. 8/2015)
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175.
Rapid Synthesis of D‐A′‐π‐A Dyes through a One‐Pot Three‐Component Suzuki–Miyaura Coupling and an Evaluation of their Photovoltaic Properties for Use in Dye‐Sensitized Solar Cells
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Shunsuke Irie Dr. Shinichiro Fuse Dr. Masato M. Maitani Prof. Yuji Wada Dr. Yuhei Ogomi Prof. Shuzi Hayase Dr. Tatsuo Kaiho Dr. Hisashi Masui Dr. Hiroshi Tanaka Prof. Takashi Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2507-2514
Twenty‐four D‐A′–π‐A dyes were rapidly synthesized through a one‐pot three‐component Suzuki–Miyaura coupling reaction, which was assisted by microwave irradiation. We measured the absorption spectra, electrochemical properties, and solar‐cell performance of all the synthesized dyes. The D5 πA4 dye contained our originally designed rigid and nonplanar donor and exerted the highest efficiency at 5.4 %. The short‐circuit current (Jsc) was the most important parameter for the conversion efficiency (η) in the case of the organic D‐A′‐π‐A dyes. Optimal ranges for the D‐A′‐π‐A dyes were observed for high values of Jsc/λmax at λ=560–620 nm, an optical‐absorption edge of λ=690–790 nm, and EHOMO and ELUMO values of <1.14 and ?0.56 to ?0.76 V, respectively. 相似文献
176.
6‐Azido‐6‐deoxy‐l‐idose as a Hetero‐Bifunctional Spacer for the Synthesis of Azido‐Containing Chemical Probes
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Hiroki Hamagami Dr. Motofumi Kumazoe Dr. Yoshiki Yamaguchi Dr. Shinichiro Fuse Prof. Dr. Hirofumi Tachibana Dr. Hiroshi Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12884-12890
The design of 6‐azido‐6‐deoxy‐l ‐idose for use as a hetero‐bifunctional spacer is reported. The hemiacetal at one terminus is an equivalent of an aldehyde and can react with nucleophiles, such as amino groups and electron‐rich aromatics. The azido group at the other terminus bio‐orthogonally undergoes a Hüisgen [3+2] cycloaddition with an acetylene. The idose derivative exhibited a higher level of reactivity towards oxime formation than a corresponding glucose derivative. The 13C NMR spectrum of the uniformly 13C‐labeled 6‐azido‐idose indicated that the acyclic forms of the sugar totaled 0.3 % of all the isomers, whereas those of glucose totaled 0.01 %. The larger population of the acyclic forms of the idose derivative would result in higher reactivity towards electrophilic addition in comparison with glucose derivatives. Finally, we prepared a C‐idosyl epigallocatechin gallate (EGCG) that bears an azido group through C‐glycosylation of EGCG with 6‐azido‐idose. This glycosyl form of the C‐idosyl EGCG exhibited a cytotoxicity against U266 cells that was comparable to that of EGCG. These results suggested that the EGCG derivative could be used as an effective chemical probe for the elucidation of EGCG biological functions. 相似文献
177.
The Synthesis of trans‐Flavan‐3‐ol Gallates by Regioselective Oxidative Etherification and Their Cytotoxicity Mediated by 67 LR
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Nana Shiraishi Dr. Motofumi Kumazoe Dr. Shinichiro Fuse Prof. Dr. Hirofumi Tachibana Dr. Hiroshi Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13050-13053
We report on a chiral pool approach for the synthesis of trans‐flavan‐3‐ol gallates from epichlorohydrin. The trans‐flavan‐3‐ol gallates were prepared by the cycloetherification of the phenol at the C2 benzylic position of 2‐acylozyl‐1,3‐diarylpropane during regioselective C?H oxidation. The 1,3‐diarylpropanes were prepared starting from epichlorohydrin by epoxide opening with A and B ring precursors, followed by acylation of the resultant alcohol with galloyl chloride. The availability of both the enantiomers of epichlorohydrin allowed the preparation of the corresponding enantiomer using the same procedure. The cytotoxicity of the compounds against U266 cells was tested, in which 5‐deoxy‐7,3′‐O‐dimethyl gallocatechin gallate exhibited cytotoxicity that was more than ten times stronger than natural (?)‐EGCG. In addition, the absolute configuration of the derivatives did not critically affect the biological activity. 相似文献
178.
179.
Rapid Synthesis of Thiophene‐Based,Organic Dyes for Dye‐Sensitized Solar Cells (DSSCs) by a One‐Pot,Four‐Component Coupling Approach
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Keisuke Matsumura Soichi Yoshizaki Dr. Masato. M. Maitani Prof. Yuji Wada Dr. Yuhei Ogomi Prof. Shuzi Hayase Dr. Tatsuo Kaiho Dr. Shinichiro Fuse Dr. Hiroshi Tanaka Prof. Takashi Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9742-9747
This one‐pot, four‐component coupling approach (Suzuki–Miyaura coupling/C?H direct arylation/Knoevenagel condensation) was developed for the rapid synthesis of thiophene‐based organic dyes for dye‐sensitized solar cells (DSSCs). Seven thiophene‐based, organic dyes of various donor structures with/without the use of a 3,4‐ethylenedioxythiophene (EDOT) moiety were successfully synthesized in good yields based on a readily available thiophene boronic acid pinacol ester scaffold (one‐pot, 3‐step, 35–61 %). Evaluation of the photovoltaic properties of the solar cells that were prepared using the synthesized dyes revealed that the introduction of an EDOT structure beside a cyanoacrylic acid moiety improved the short‐circuit current (Jsc) while decreasing the fill factor (FF). The donor structure significantly influenced the open‐circuit voltage (Voc), the FF, and the power conversion efficiency (PCE). The use of a n‐hexyloxyphenyl amine donor, and our originally developed, rigid, and nonplanar donor, both promoted good cell performance (η=5.2–5.6 %). 相似文献
180.