論文 - 阿部　洋

The bisected s-trans conformation-controlled highly stereoselective addition of Grignard reagents to C-cyclopropylaldonitrone. An efficient synthesis of 1-phenyl-2-[(S)-1-aminoalkyl]-N,N-diethylcyclopropanecarboxamides, a new class of potent NMDA receptor antagonists 査読有り

Y Kazuta, S Shuto, H Abe, A Matsuda

JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   1 巻 ( 6 ) 頁： 599 - 604   2001年

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

An efficient synthesis of 1-phenyl-2-[(S)-1-aminoethyl]- and 1-phenyl-2-[(S)-1-aminopropyl]-N,N-diethylcyclopropanecarboxamides [1a (PEDC) and 1b (PPDC), respectively], potent NMDA receptor antagonists having a cyclopropane structure, was achieved. We have shown for the first time that C-cyclopropylaldonitrone preferentially exists in the bisected s-trans conformation, due to the characteristic stereoelectronic effects of the cyclopropane ring, by X-ray crystallographic analysis, NMR studies, and theoretical calculations. Based on these findings, the highly stereoselective addition reaction of Grignard reagents to C-cyclopropylaldonitrone 6 was developed, and the reaction was successfully used as the key step for the preparation of the NMDA receptor antagonists 1a and 1b as well as for a newly designed isopropyl-type congener 1c. The facial selectivity of the addition of Grignard reagents can be explained by the attack of the reagents from the less hindered side of the substrate in the predicted bisected s-trans conformation. This Grignard reaction is the first example of a highly stereoselective addition to a nitrone via a non-chelation controlled pathway.

DOI： 10.1039/b008230i

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Intracellular Ca2+-mobilizing adenine nucleotides. Synthesis and biological activity of cyclic ADP-carbocyclic-ribose and C-glycosidic analog of adenophostin A

    頁： 461-470   2001年

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The stereoselective synthesis of 4 '-beta-thioribonucleosides via the Pummerer reaction 査読有り

T Naka, N Minakawa, H Abe, D Kaga, A Matsuda

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   122 巻 ( 30 ) 頁： 7233 - 7243   2000年8月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

An efficient stereoselective synthesis of 4'-beta-thioribonucleosides 14, 15, 27, and 30 using the Pummerer reaction as the key step is described. The Pummerer reaction of 1,4-anhydro-2-0-(2,4-dimethoxybenzoyl)-3,5-O-( 1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-3-sulfinyl-D-ribitol (R-10:S-10 = 2.7:1) in the presence of silylated uracil afforded the desired p-anomer of the 4'-thiouridine derivative 11 in 66% yield without formation of its a-anomer. The reaction with R-10 gave 11 in 87% yield, while the one with S-10 resulted in a 27% decrease of the desired product 11 along with a 22% yield of 3,6-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-3-hydroxy-2-hydroxymethylthiophene (12). A likely explanation for the observed difference in the reaction of R-10 and S-10 is that the reaction proceeds via an E2 type pathway, which prefers anti elimination. Thus, R-10 would preferentially afford the alpha-thiocarbocation intermediate 21 via an E2 anti elimination under the reaction conditions. The resulting 21 would be expected to react with silylated uracil stereoselectively to give 11 in good yield. However, formation of the more stable tertiary alpha-thiocarbocation intermediate 23, which would prefer to give 12 and/or to decompose, would compete with the formation of the desired 21 in the reaction with S-10. Consequently, this argument would explain the low yields of the desired product 11 and the poor mass balance in the reaction with S-10. When the sulfoxide 10 (R-10:S-10 = >16:1) prepared by oxidation of 9 with ozone was used for the Pummerer reaction, the desired 11 was obtained in 80% yield. Compound 11 was converted to 4'-beta-thiouridine (14) by treatment of 11 with ammonium fluoride, followed by methanolic ammonia. Similarly, 4'-beta-thiocytidine (15) was prepared when silylated N-4-acetylcytosine was used in the Pummerer reaction. For the Pummerer reactions with purine bases, 6-chloropurine and 2-amino-6-chloropurine were found to be the most suitable. When the reactions were conducted in a mixture of acetonitrile and 1,2-dichloroethane at room temperature, followed by reflux, the desired products 25 and 28 were obtained in 65% and 56% yields, respectively. These compounds were then converted to 4'-beta-thioadenosine (27) and 4'-beta-thioguanosine (30) under the usual conditions. This is therefore the first time that the stereoselective synthesis of 4'-beta-thioribonucleosides has been performed using the neighboring group participation of the Pummerer reaction.

DOI： 10.1021/ja000541o

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Synthesis of the C-glycosidic analogue of adenophostin A and its uracil congener as potential IP3 receptor ligands. Stereoselective construction of the C-glycosidic structure by a temporary silicon-tethered radical coupling reaction 査読有り

H Abe, S Shuto, A Matsuda

JOURNAL OF ORGANIC CHEMISTRY   65 巻 ( 14 ) 頁： 4315 - 4325   2000年7月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Synthesis of the C-glycosidic analogue 9 of adenophostin A, a very potent IP3 receptor agonist, and its uracil congener 10 was achieved via a temporary silicon-tethered radical coupling reaction as the key step. Phenyl 3,4,6-tri-O-(p-methoxybenzyl)-1-seleno-beta-D-glucopyranoside (27) and 3-deoxy3-methylene-1,2-O-isopropylidene-alpha-D-erythro (30) were connected by a dimethylsilyl tether to give the radical coupling reaction substrate 24, which was successively treated with Bu-3-SnH/AIBN in benzene and TBAF in THF to give the coupling product 25 with the desired (3a,1'a)-configuration as the major product. From 25, the targets 9 and 10 were synthesized via introduction of adenine or uracil base by Vorbruggen's method and phosphorylation of the hydroxyls by the phosphoramidite method.

DOI： 10.1021/jo0001333

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Stereoselective synthesis of alpha and beta-C-glucosides via radical cyclization with an allylsilyl tether. Control of the stereoselectivity by changing the conformation of the pyranose ring 査読有り

S Shuto, M Terauchi, Y Yahiro, H Abe, S Ichikawa, A Matsuda

TETRAHEDRON LETTERS   41 巻 ( 21 ) 頁： 4151 - 4155   2000年5月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

An efficient method for preparing both 1 alpha- and 1 beta-C-glucosides having a 3-hydroxypropyl group at the anomeric position via a radical cyclization reaction with an allylsilyl tether was developed. The stereoselectivity of the radical cyclization can be controlled by the conformation of the pyranose ring, which is effectively manipulated by the hyroxyl protecting groups. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(00)00556-6

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Synthesis of the C-glycosidic analog of adenophostin A, a potent IP3 receptor agonist, using a temporary silicon-tethered radical coupling reaction as the key step 査読有り

H Abe, S Shuto, A Matsuda

TETRAHEDRON LETTERS   41 巻 ( 14 ) 頁： 2391 - 2394   2000年4月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Synthesis of the C-glycosidic analog (3) of adenophostin A, a very potent IP3 receptor agonist, was achieved using a temporary silicon-tethered reductive radical coupling reaction as the key step. Radical reaction of the silaketal substrate 6 with Bu3SnH/AIBN in benzene occurred stereoselectively, and subsequent desilylation gave the desired C-glycosidic disaccharide 7 with the (3 alpha,1'alpha)-configuration as the major product. Compound 7 was converted into the target 3 via the introduction of an adenine base by a Vorbruggen glycosylation reaction. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(00)00171-4

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Mechanistic study of the ring-enlargement reaction of (3-oxa-2-silacyclopentyl)methyl radicals into 4-oxa-3-silacyclohexyl radicals. Evidence for a pentavalent silicon-bridging radical transition state in 1,2-rearrangement reactions of beta-silyl radicals 査読有り

S Shuto, Sugimoto, I, H Abe, A Matsuda

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   122 巻 ( 7 ) 頁： 1343 - 1351   2000年2月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

A mechanistic study was performed on a novel radical ring-enlargement reaction of (3-oxa-2-silacyclopentyl)methyl radicals into 4-oxa-3-silacyclohexyl radicals. Two pathways, one via a pentavalent silicon bridging radical transition state (or intermediate), the other via beta-elimination to give a ring-opened silyl radical, can be postulated. The radical reactions of 1 and 2, which are precursors for a (3-oxa-2-silacyclopentyl)methyl radical C' and a 4-oxa-3-silacyclohexyl radical D', respectively, showed that the ring-enlargement rearrangement of C' into D' is irreversible. H-1 NMR analysis of the radical reactions of 8a and 8b, which have an asymmetric center at silicon, indicated that the configuration at the silicon atom is retained via a pentavalent silicon-bridging radical transition state (or intermediate) during the ring-enlargement reaction. Furthermore, examination of the radical ring-enlargement reaction with a deuterium-labeled substrate 12D showed that the ring-enlargement reaction did not involve beta-elimination to give a ring-opened silyl radical. Based on these results, we conclude that the ring-enlargement reaction occurs via a pentavalent silicon-bridging radical transition state (or intermediate). This is the first experimental evidence for such a pentavalent silicon radical, which has been previously postulated to understand radical reactions of organic silicon compounds.

DOI： 10.1021/ja993239s

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Conjugation of dipeptide to fluorescent dyes enhances its affinity for a dipeptide transporter (PEPT1) in human intestinal Caco-2 cells 査読有り

H Abe, M Satoh, S Miyauchi, S Shuto, A Matsuda, N Kamo

BIOCONJUGATE CHEMISTRY   10 巻 ( 1 ) 頁： 24 - 31   1999年1月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Dipeptide transporters in small intestine have a very wide substrate specificity, so that the transporter sometimes serves as a carrier for peptide-like compounds. We have synthesized dipeptide analogues conjugated at an E-amino group of Lys in Val-Lys or Lys-Sar with fluorescent compounds such as fluorescein isothiocyanate and coumarin-3-carboxylic acid. Uptakes of these peptide analogues were examined by measuring intracellular accumulations into monolayers of the human intestinal epithelial cell line Caco-2 expressing the dipeptide transporter PEPT1. Kinetic analysis and effects of addition either of uncoupler (protonophore) or by Gly-Sar, one of the good substrates of PEPT1, revealed that fluorescent dipeptides were taken up by passive diffusion. In contrast, these analogues remarkably inhibited the Gly-Sar uptake by Caco-2 cells. Among the fluorescent analogues synthesized in this paper, Vaf-Lys(Flu) was the most potent competitive inhibitor against the Gly-Sar uptake with an inhibition constant of 5 mu M. This value is the smallest among those ever reported: Val-Lys(Flu) has the highest affinity for PEPT1 among chemicals ever reported. The importance of the hydrophobic part of the substrate was pointed out.

DOI： 10.1021/bc980049i

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