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Volume 56, Issue 11
Displaying 1-10 of 10 articles from this issue
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Takeshi Kitahara, Hidenori Watanabe1998 Volume 56 Issue 11 Pages 884-895
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSEnantioselective synthesis of bioregulators with remarkable biological activities has been accomplished. The target molecules are plant growth regulators (methyl eptjasmonate and analogs, pironetin), plant pathogenic toxins (oxygenated eremophilanes, sorokinianin) and substances related to plant protection (tanabalin; insect antifeedant, mugineic acid and analogs; phytosiderophore).View full abstractDownload PDF (1405K) -
Yoshiaki Kiso1998 Volume 56 Issue 11 Pages 896-907
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThe HIV-1 protease analogs were synthesized by the solid-phase method and the dimer analog covalently linked by a disulfide bridge was constructed using the thioether chemical ligation method. The HIV-1 protease analogs effectively cleaved the Tyr-Phe-type substrate, but had weak affinity to the Tyr-Pro-type substrate. Consequently, the molecular recognition of the analogs differs from the wild-type enzyme.
Based on the substrate transition-state mimetic concept, allophenylnorstatine-containing HIV protease inhibitors were designed and synthesized. Among them, a dipeptide-based HIV protease inhibitor, KNI-764, exhibited potent antiviral activities, low cytotoxicity and good pharmacokinetic properties. Also, KNI-764 showed strong inhibition against both wild-type HIV-1 protease and synthetic HIV protease analogs, whereas saquinavir, ritonavir, and indinavir weakly inhibited the synthetic protease analogs. This study suggests that the small-sized dipeptide HIV protease inhibitor, KNI-764, is a good candidate for anti-HIV drugs.View full abstractDownload PDF (1251K) -
Kiitiro Utimoto, Seijiro Matsubara1998 Volume 56 Issue 11 Pages 908-918
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThe following three types of samarium diiodide mediated reactions qf organic halides and carbonyl compounds are discussed : 1) Samarium-mediated highly stereoselective reaction of 1, 1-dihaloalkanes with aldehydes. 2) Stereoselective reaction with configurationally stable α-phenylthioalkylsamarium compounds. 3) Preparation and reaction of a samarium enolate equivalent of β-ketoester.View full abstractDownload PDF (1065K) -
Naokazu Kano, Norihiro Tokitoh, Renji Okazaki1998 Volume 56 Issue 11 Pages 919-930
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSDivalent organolead compounds (plumbylenes) and lead-sulfur double-bond compounds (plumbanethiones) were synthesized by taking advantage of the kinetic stabilization method, and their crystal structures, spectroscopic properties and reactivities were investigated. Thermal reaction of a plumbanethione afforded an aryl (arylthio) plumbylene via 1, 2-aryl migration.View full abstractDownload PDF (1583K) -
Yoshio Okahata, Toshiaki Mori1998 Volume 56 Issue 11 Pages 931-939
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSA new way of solubilizing hydrolytic enzymes in organic media was achieved by coating the enzyme with lipid monolayers. Lipid-coated enzymes have been used successfully for a number of types of reactions in organic media or organic-aqueous two-phases, for example, enantioselective esterification by lipase, transphosphatidylation of water-insoluble phospholipids by phospholipase D, hydrolysis of lipophilic substrates by a catalytic antibody, and transglycosylation by β-D-galactosidase.View full abstractDownload PDF (1061K) -
Tadashi Nakata1998 Volume 56 Issue 11 Pages 940-951
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSTwo efficient methods for the synthesis of the cyclic ethers, the important fundamental components of marine polycyclic ethers, were developed : (1) rearrangement-ring expansion reaction and (2) endo-cyclization of hydroxy styrylepoxide. Based on the newly developed methods, stereoselective total synthesis of hemibrevetoxin B (2) has been completed.View full abstractDownload PDF (1325K) -
Osamu Kanie, Tomoya Ogawa, Yukishige Ito1998 Volume 56 Issue 11 Pages 952-962
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSDue to high demand to access biologically important oligosaccharide structures, efficient and stereoselective synthetic methods are required. This article addresses these two issues from our recent studies. The first part deals with β-mannosylation and α-sialylation known as the two most difficult glycosylation reactions which were now made possible by means of an “intramolecular aglycon delivery” system and control by “auxiliary”, respectively. In the second part, the remarkably efficient “orthogonal glycosylation strategy” which was developed based on tactical analysis of oligosaccharide synthesis is described.View full abstractDownload PDF (1349K) -
Yasuyuki Kita, Shuji Akai, Hiromichi Fujioka1998 Volume 56 Issue 11 Pages 963-974
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThis account highlights our very recent approaches towards asymmetric total synthesis of the potent antitumor antibiotic, fredericamycin A. Due to its quite unique structure, effective methodology for its asymmetric synthesis has rarely been presented, and the absolute configuration still remains unknown. The key feature of our approaches involves the protocols for the construction of its peri-hydroxy polyaromatic skeleton bearing the chirality at the spiro carbon via (i) intramolecular [4+2] cycloaddition of silylene-protected dihydroxystyrene derivatives, (ii) aromatic Pummerer-type reaction, and (iii) intermolecular [4+2] cycloaddition of homophthalic anhydrides. Particular attention has been given to the novel syntheses of the optically active spiro carbon center by (i) enzymatic asymmetrization of 2, 2-disubstituted 1, 3-diols and (ii) stereospecific rearrangement of optically active epoxy acylates.View full abstractDownload PDF (1352K) -
Koichi Mikami, Toshinobu Korenaga, Satoru Matsukawa, Yousuke Matsumoto ...1998 Volume 56 Issue 11 Pages 975-986
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSIn asymmetric catalytic reactions, racemic catalysts inherently give only racemic products, whereas non-racemic catalysts generate non-racemic products with or without a non-linear relationship. Conversely, we report herein as an account a conceptually new strategy for asymmetric catalysis using racemic catalysts wherein a chiral additive selectively activates, rather than de-activates, one enantiomer of the racemic catalyst.View full abstractDownload PDF (1521K) -
Takashi Takahashi, Hiroshi Tanaka, Takayuki Doi, Haruo Yamada1998 Volume 56 Issue 11 Pages 987-999
Published: November 01, 1998
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThis account describes our design, syntheses and DNA cleaving activities of a series of 9-membered masked enediyne analogues 8, 9, 19, 30, 44, 46, 47, 48, 49, and 50. In the first part of this report, we describe the development of a new method for the construction of 9-membered enediyne structures of NCS 8 and kedarcidin-C1027 9. The method involves the transannular [2, 3] -Wittig rearrangement of the 12-membered cyclic ether to construct the highly strained 9-membered diyne. In the second part of this report, we describe the syntheses of the masked enediyne analogues of NCS 19 and kedarcidin-C1027 30 possessing trans-hydroxy groups at C (10) and C (11). Palladium-catalyzed ring-opening of the ene-oxides 27 and 34 was applied to the introduction of the trans relative stereochemistry at C (10) and C (11) for the attachment of DNA recognition elements. Phthalic acid serves as a suitable “trigger” to control the stability of the 9-membered diynes and to generate enediynes for the DNA cleaving experiment. Both 19 and 30 caused DNA cleavage with the formation of Form II and Form III. In the last part of this report, we describe the synthesis of the masked enediyne analogues 44, 46, 47, 48, 49, and 50 possessing the DNA intercalator of NCS and/or sugar moieties. DNA cleaving experiments of 44 showed that introduction of the DNA intercalators improved DNA cleaving activity about 10 fold compared with the corresponding alcohol 30. Introduction of sugar moieties to the masked enediyne was achieved via S-alkylation of a bromoacetate derivative with a sugar-containing thiol without the need for protection of the sugar moiety. DNA cleaving experiments showed that the masked enediyne analogues 46, 47, 48, 49, and 50 possessing sugar moieties induced sequence-selective DNA cleavage and that the simple sugars serve as a DNA recognition element for DNA cleavage.View full abstractDownload PDF (2019K)
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