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721.
Treatment of 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from ketones and chloromethyl p-tolyl sulfoxide, with ethylmagnesium chloride or isopropylmagnesium chloride at below -78 degrees C gave magnesium alkylidene carbenoids in about 90% yields. The reaction of the generated carbenoids with lithium alpha-sulfonyl carbanions was found to afford tri- and tetra-substituted allenes. Both cyclic ketones and acyclic ketones were useful in this procedure. However, the 1-chlorovinyl p-tolyl sulfoxides derived from aldehydes gave only rearranged products, acetylenes, under the reaction conditions. The magnesium alkylidene carbenoid derived from an optically active 1-chlorovinyl p-tolyl sulfoxide was treated with lithium alpha-carbanion of 1-naphthyl phenyl sulfone; however, the obtained allene was found to be racemic. The mechanism of this reaction is also discussed. 相似文献
722.
Assoc. Prof. Mineto Uchiyama Yukihiro Murakami Prof. Kotaro Satoh Prof. Masami Kamigaito 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215021
We report a novel method to synthesize degradable poly(vinyl ether)s with cleavable thioacetal bonds periodically arranged in the main chains using controlled cationic copolymerization of vinyl ethers with a 7-membered cyclic thioacetal ( 7-CTA ) via degenerative chain transfer (DT) to the internal thioacetal bonds. The thioacetal bonds, which are introduced into the main chain by cationic ring-opening copolymerization of 7-CTA with vinyl ethers, serve as in-chain dormant species to allow homogeneous propagation of vinyl ethers for all internal segments to afford copolymers with controlled overall and segmental molecular weights. The obtained polymers can be degraded into low- and controlled-molecular-weight polymers with narrow molecular weight distributions via hydrolysis. Various vinyl ethers with hydrophobic, hydrophilic, and functional pendants are available. Finally, one-pot synthesis of multiblock copolymers and their degradation into diblock copolymers are also achieved. 相似文献
723.
Kawasaki N Miyataka H Nishiki M Matsumoto H Inagaki N Nagai H Satoh T 《Chemical & pharmaceutical bulletin》1999,47(2):177-181
A novel series of trimethylhydroquinone derivatives was synthesized and evaluated for their anti-lipid peroxidation activity in rat liver microsomes, inhibition of rat basophilic leukemia-1 (RBL-1) cell 5-lipoxygenase and 48 h homologous passive cutaneous anaphylaxis (PCA) activity in rats. 4-[4-[4-(Diphenylmethyl)-1-piperazinyl]-butoxy]-2,3,6-trimethyl phenol (9c) exhibited the ability to inhibit Fe(3+)-ADP induced NADPH dependent lipid peroxidation (IC50 = 5.3 x 10(-7) M), 5-lipoxygenase ((IC50 = 3.5 x 10(-7) M) and PCA reaction (57% inhibition at 100 mg/kg p.o.). 相似文献
724.
725.
Dr. Yuta Maki Kazuki Kawata Dr. Yanbo Liu Kang-Ying Goo Dr. Ryo Okamoto Prof. Dr. Yasuhiro Kajihara Dr. Ayano Satoh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(37):e202201253
Glycosylation of proteins is known to be essential for changing biological activity and stability of glycoproteins on the cell surfaces and in body fluids. Delivering of homogeneous glycoproteins into the endoplasmic reticulum (ER) and the Golgi apparatus would enable us to investigate the function of asparagine-linked (N-) glycans in the organelles. In this work, we designed and synthesized an intentionally glycosylated cholera toxin B-subunit (CTB) to be transported to the organelles of mammalian cells. The heptasaccharide, the intermediate structure of various complex-type N-glycans, was introduced to the CTB. The synthesized monomeric glycosyl-CTB successfully entered mammalian cells and was transported to the Golgi and the ER, suggesting the potential use of synthetic CTB to deliver and investigate the functions of homogeneous N-glycans in specific organelles of living cells. 相似文献
726.
Hideyuki Suzuki Ikkyu Satoh Hiromi Nishioka Yasuo Takeuchi 《Tetrahedron letters》2017,58(40):3834-3837
A simple and straightforward semihydrogenation of alkyne to alkene with triethanolamine and formic acid in the presence of PdCl2 has been described. Although hydrogenation using formic acid as a hydrogenation source has been used in combination with amines previously, few reports are available concerning the associated reactivity. We demonstrated that reactivity changes depending on the type of amine used in the hydrogenation. Further, this reaction requires no strict time control, making it a useful tool in organic synthesis. 相似文献
727.
Characterization of a polysaccharide having activity on the reticuloendothelial system from the stolon of Glycyrrhiza glabra var. glandulifera. 总被引:1,自引:0,他引:1
An acidic polysaccharide, named glycyrrhizan GA, was isolated from the stolon of Glycyrrhiza glabra L. var. glandulifera Reg. et Herd. It produced a single band on electrophoresis and a single peak on gel chromatography, and its molecular mass was estimated to be 85,000. Glycyrrhizan GA is composed of L-arabinose: D-galactose: L-rhamnose: D-galacturonic acid: D-glucuronic acid in the molar ratio of 22:10:1:2:1, in addition to small amounts of O-acetyl groups. Part of the hexuronic acid residues exist as methyl esters. Methylation analysis, carbon-13 nuclear magnetic resonance and periodate oxidation studies indicated that its structural features include mainly alpha-arabino-beta-3,6-galactan type structural units. Glycyrrhizan GA showed remarkable reticuloendothelial system-potentiating activity in a carbon clearance test. 相似文献
728.
729.
Toshifumi Satoh Tomoko Imai Yoshikazu Kitajyo Takahiro Maeda Atsushi Narumi Harumi Kaga Noriaki Kaneko Toyoji Kakuchi 《Macromolecular Symposia》2004,217(1):39-46
The thermally induced cationic polymerizations of 1,6-anhydro-β-D -glucopyranose ( 1a ), 1,6-anhydro-β-D -mannopyranose ( 1b ) and 1,6-anhydro-β-D -galactopyranose ( 1c ) as a latent cyclic AB4-type monomer were carried out using (S-2-butenyl)tetramethylenesulfonium hexafluoroantimonate ( 2 ) as an initiator. The solution polymerization in propylene carbonate proceeded without gelation to produce the water-soluble hyperbranched polysaccharides ( 3a-c ) with controlled molecular weights and narrow polydispersities. The degree of branching (DB), estimated by the methylation analysis of 3a-c , was in the range of 0.38 – 0.49. The thermally induced cationic polymerization of 1a-c using 2 is a facile method leading to a hyperbranched polysaccharide with a high DB value. 相似文献