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Volume 64, Issue 7
Displaying 1-9 of 9 articles from this issue
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Hiroshi Ohrui, Hiroyuki Hayakawa, Satoru Kohgo, Masao Matsuoka, Eiichi ...2006 Volume 64 Issue 7 Pages 716-723
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSAlthough the Highly Active Anti-Retroviral Therapy (HAART) has dramatically improved the quality of life and the prognosis of patients infected with HIV, development of more active and less toxic drugs that prevent the emergence of drug-resistant HIV variants is strongly required, due to the emergence of new drug-resistant HIV variants, need of taking a large quantity of drugs, and side effects of the drugs.
The principal author has proposed a concept to prevent the emergence of the HIV variants resistant to reverse-transcriptase (RT) inhibitory nucleosides. Based on the concept, 4'-C-substituted-2'-deoxynucleoside (4'Sd-N) was designed as the anti-HIV nucleoside that could prevent the emergence of resistant HIV variants. Various kinds of 4'Sd-N were synthesized and evaluated for biological activity.
2'-Deoxy-4'-C-ethynyl-2-fluoroadenosine (4'Ed-2FA) which is stable to adenosine deaminase turned out to be highly active against all HIV-1 including multi-drug resistant variants and very lowly toxic, and so far no HIV-1 variants resistant to it emerged. These results suggest that once-daily-dosing schedule of 4'Ed-2FA is possible presumably with few side effects and warrant that 4'Ed-2FA be further developed as a potential therapeutic for HIV-1 infection.View full abstractDownload PDF (1183K) -
Nobukazu Taniguchi, Yoshie Tanaka, Motokazu Uemura2006 Volume 64 Issue 7 Pages 724-734
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSChiral β-diols, diamines and amino alcohols are significantly important compounds in asymmetric reaction. These compounds were prepared by samarium diiodide-mediated reductive coupling of planar chiral transition metal complexes. Planar chiral ortho-substituted benzaldehyde tricarbonyl chromium complexes were treated with samarium diiodide to give optically pure β-diols. Similarly, planar chiral benzaldimine chromium complexes afforded β-diamines in enantiopure form. Furthermore, reductive cross-coupling of planar chiral aldehydes with N-tosyl aldimines gave optically pure β-amino alcohols without formation of homo-coupling products. Thus, samarium diiodide-mediated reductive cross-coupling of N-tosylferrocenylideneamines with planar chiral ferocenecarboxaldehydes or benzaldehyde chromium complexes gave optically pure anti-β-amino alcohols. On the other hand, the reductive cross coupling of N-tosyl benzylideneamines with planar chiral aldehydes afforded optically pure syn-β-amino alcohols.View full abstractDownload PDF (1545K) -
Nagao Kobayashi, Atsuya Muranaka2006 Volume 64 Issue 7 Pages 735-743
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThe utility of circular dichroism (CD) and magnetic circular dichroism (MCD) is presented with typical examples. Thus, conformation of natural ortho-diols is determined by modifying the diols by macrocyclic compounds and by analyzing their CD spectra. The sign of the CD spectra is confirmed to be plus in the left-handed circumstances, while minus in the right-handed circumstances. The helix sense of artificial β-polypeptides is determined by the theoretical analysis of their CD spectra. The chirality of a system comprising of two porphyrins and a chiral amine is determined by the analysis of its CD and MCD spectra. The assignments of electronic absorption bands of porphyrinic sandwich compounds are unambiguously determined in consideration of MCD theory. In almost all these cases, the spectra are interpreted based on the concept of CD and MCD theory, and in some cases, molecular orbital calculations lend support to the results.View full abstractDownload PDF (1373K) -
Development of Catalytic ReactionsMugio Nishizawa, Hiroshi Imagawa2006 Volume 64 Issue 7 Pages 744-751
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSHg (OTf)2, developed in our group in 1983 as an olefin cyclization agent, has been developed further into a powerful catalyst for the hydration of terminal alkynes leading to methyl ketones. The reaction is speculated to involve Hg2+-induced hydration of alkyne followed by protodemercuration caused by the in situ generated TfOH that also results in the regeneration of Hg (OTf)2. In the presence of an appropriately placed double bond or an aromatic ring, enyne as well as arylyne cyclizations take place with 1000 catalytic turnover. The cyclization of yne-en-aryl substrates leading to tricarbocycles is the first Hg2+-catalysed biomimetic tandem cyclization. Hg (OTf)2 is useful not only for carbon-carbon bond formation but also for the synthesis of heterocycles such as furans, indoles, and exomethylene enol lactones. A novel Hg (OTf) 2-catalyzed glycosylation using alkynoate as leaving group has also been developed. This protocol is useful for the preparation of hindered glycosides. Hg (OTf)2-catalyzed reaction of an internal propargyl acetate with water constitutes a novel procedure for enone synthesis.View full abstractDownload PDF (1540K) -
Teruhisa Tsuchimoto2006 Volume 64 Issue 7 Pages 752-765
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSLewis acids have been used as a mediator or a catalyst so far mainly for activation of heteroatom-containing compounds like carbonyl compounds, imines and alkyl halides. In contrast, we have been focusing on developing new carbon-carbon bond forming reactions utilizing activation of hydrocarbons by a metal sulfonate catalyst. In this context, we found that arenes as well as heterocyclic arenes add to alkynes in the presence of indium triflate [In (OTf)3, Tf=SO2CF3] as a catalyst. These findings are followed by development of facile synthesis of aryl-and heteroarylannulated [a] carbazoles by the reaction of propargyl ethers with 2-aryl-and 2-heteroarylindoles. In addition to the above reactions, metal triflates catalyzed dimerization of vinylarenes with the aid of a palladium catalyst (activation of C = C), nucleophilic substitution using a pyrrolyl group as a carbon leaving group (activation of C-C) and oxidative coupling between lactams and heterocyclic arenes (activation of C-H).View full abstractDownload PDF (2083K) -
Masaru Hashimoto2006 Volume 64 Issue 7 Pages 766-777
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThis paper describes the synthetic studies of sulfur substituted oligosaccharides performed in our laboratory. Efficient and α-selective glycosidation reactions with 5-thiopyranoses were realized employing 1-O-trichloroacetimidates of 5-thiopyranoses carrying 2-OΟ-etheral protective groups. These conditions were applied for the synthesis of sulfur substituted maltose and isothiomaltose derivatives. The Pummerer rearrangement of 2, 3-O-isopropylidene protected 1-dehydrothiopyranose oxide was found to proceed at the C 1 position regioselectively to provide 5-thiopyranose derivative. Experiments employing labeled compound revealed the reaction mechanism. Development of 3-cyano-3-tert-butyldimethylsilyl-propyl (CSP group) thioether brought us an successful synthesis of sulfur substituted galacturonic acid. Enzymatic properties of these analogue against endo-glycosidases are also described.View full abstractDownload PDF (2267K) -
Shigeki Matsunaga2006 Volume 64 Issue 7 Pages 778-779
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThis mini review focuses on the recent advances in catalytic intermolecular hydroaminations : Pd-, Ni-, Rh-, and Ru-catalyzed addition reactions of amine to olefins, and their mechanistic insights are described concisely. Oxidative addition of ammonia to an Ir complex to activate the N-H bond is mentioned as well, that is a milestone achievement toward the intermolecular hydroamination using ammonia as a nitrogen source.View full abstractDownload PDF (368K) -
Takanori Matsuda2006 Volume 64 Issue 7 Pages 780-781
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThe catalytic transformation of inert C-H bonds to other functional groups is one of the most active research areas in organic and organometallic chemistry because such reactions present possibilities to exploit readily available starting materials, shorten reaction sequences, and synthesize compounds that are otherwise difficult to prepare. In this review, recent advances in the catalytic functionalization of unactivated sp3 C-H bonds are briefly introduced. The sp3 C-H bonds were transformed to C-C and C-O bonds through activation with transition metal catalysts assisted by chelation of directing groups or a cyclometalation process.View full abstractDownload PDF (334K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese]2006 Volume 64 Issue 7 Pages 782
Published: July 01, 2006
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSDownload PDF (186K)
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