Journal of Synthetic Organic Chemistry, Japan
Online ISSN : 1883-6526
Print ISSN : 0037-9980
ISSN-L : 0037-9980
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Volume 73, Issue 1
Displaying 1-11 of 11 articles from this issue
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Preface
Reviews and Accounts
  • Total Synthesis of Telomestatin and its Analogues
    Takayuki Doi, Masahito Yoshida, Kazuaki Shibata
    2015 Volume 73 Issue 1 Pages 3-13
    Published: 2015
    Released on J-STAGE: February 20, 2015
    DOIhttps://doi.org/10.5059/yukigoseikyokaishi.73.3
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    We have achieved a total synthesis of telomestatin and determined it absolute configuration to be (R). During the synthetic study for its enantiomer, serious epimerization in the macrolactamization was observed. The problem was overcome under the reaction conditions utilizing DPPA/HOBt/DMAPO and the (S)-isomer was synthesized. Measurement of Tm values obtained from the CD melting curves indicated that (S)-isomer stabilizes the antiparallel G-quadruplex structure of telomea more strongly than telomestatin. The (S)-isomer exhibited more potent inhibitory activity against telomerase than telomestatin. We also synthesized telomestatin analogues that are heptaoxazole macrocycles including different numbers of methyloxazole moieties or containing a bromooxazole. The bromooxazole-containing heptaoxazole analogue underwent Suzuki-Miyaura coupling leading to aryl-substituted oxazole-containing heptaoxazole analogues. Although the substituents on the oxazole moieties in the heptaoxazole macrocyclic analogues did not affect telomerase inhibitory activity, one of amino-linked S-alkylated analogues exhibited potent inhibitory activity as telomestatin.
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  • Formation of Carbon-Carbon and Carbon-Heteroatom Bonds with Iron- and Bismuth Complexes
    Kimihiro Komeyama, Ken Takaki
    2015 Volume 73 Issue 1 Pages 14-28
    Published: 2015
    Released on J-STAGE: February 20, 2015
    DOIhttps://doi.org/10.5059/yukigoseikyokaishi.73.14
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    Transition metal-catalyzed cycloisomerization of carbon-carbon multiple bonds has emerged as powerful method for construction of highly substituted all-carbon or heteroatom-containing organic flameworks, which are important and core structures in organic and natural product synthesis. However, most of the reported methods required the use of noble and precious metal catalysts. Herein, we report iron- and bismuth-catalyzed introduction of carbon- and heteroatom nucleophiles into carbon-carbon multiple bonds such as alkene, alkynes, and enynes by means of their unique Lewis acid character: σ,π-chelation effect. In addition, divalent iron complex is found to be an effective promoter for a generation of aryl radicals from aryl boronic acids. By using these methods, direct arylation of benzoquinones and heteroarenes are also reported.
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  • Development of New Synthetic Methods Based upon Carbon-Carbon Bond Activation
    Masahiro Murakami, Naoki Ishida
    2015 Volume 73 Issue 1 Pages 29-38
    Published: 2015
    Released on J-STAGE: February 20, 2015
    DOIhttps://doi.org/10.5059/yukigoseikyokaishi.73.29
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    Carbon-carbon single bonds constitute the main frameworks of organic molecules. They are non-polar, thermodynamically stable, and kinetically inert in general. Nonetheless, it would streamline synthetic pathways if carbon-carbon single bonds are subjected to site-selective cleavage and directly utilized for construction and/or functionalization of organic skeletons. We herein describe the synthetic methods we have developed based upon carbon-carbon bond activation during the past four years. Rhodium(I) complexes cleave the carbon-carbon bond of strained tert-alcohols by β-carbon elimination to generate organorhodium(I) intermediates, and thus trigger reconstruction of their frameworks into totally different ones with excellent atom economy. These reactions are combined with Norrish-Yang type photo-reactions to make thermodynamically disfavored transformations possible. Ring expansion of orthocyclophanes to metacyclophanes and enantioselective synthesis of 3-hydroxyindolines from α-(N-aryl)amino ketones present prototypical examples of organic synthesis driven by photo-energy. Also described is a restructuring reaction of N-arenesulfonylazetidinols into benzosultams.
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  • Basic Concept and Applications of AIM Dual Functional Analysis: For Better Understanding and Explanation of Experimental Results Related to Interactions
    Satoko Hayashi, Waro Nakanishi
    2015 Volume 73 Issue 1 Pages 39-52
    Published: 2015
    Released on J-STAGE: February 20, 2015
    DOIhttps://doi.org/10.5059/yukigoseikyokaishi.73.39
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    Basic concept and applications of AIM dual functional analysis (AIM-DFA) are discussed. Total electron energy densities (Hb(rc)) are plotted versus Hb(rc)-Vb(rc)/2 [=(ħ2/8m)∇2ρb(rc)] at bond critical points (BCPs) of interactions in question, where Vb(rc) are potential energy densities at BCPs. In our treatment, data of perturbed structures around fully optimized ones are employed for the plot, in addition to those of the fully optimized structures. Data of fully optimized structures correspond to the static nature, whereas those of perturbed structures with fully optimized ones represent the dynamic behavior of interactions, which we have proposed. Methods to generate the perturbed structures are also proposed. The treatment enables us to evaluate, classify, and understand well the weak to strong interactions in a unified form. Applications of AIM-DFA are explained, after confirmation of very good coincidence between calculated and experimental results, supported by the high resolution X-ray determination of ρ(r).
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  • Development of New Synthetic Reactions Using Lanthanum Metal
    Rui Umeda, Yutaka Nishiyama
    2015 Volume 73 Issue 1 Pages 53-64
    Published: 2015
    Released on J-STAGE: February 20, 2015
    DOIhttps://doi.org/10.5059/yukigoseikyokaishi.73.53
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    The utilization of lanthanoid metal salts and organolanthanoid compounds as synthestic reagents or catalysts in organic synthesis has been steadily interesting due to their unique chemical properties. Low-valent, trivalent, and tetravalent lanthanoid compounds have been widely used in organic reactions, however, the direct use of lanthanoid metal is still rare due to their low solubility in organic solvents or their instability under aerobic conditions.  In this paper, we show the various organic reactions by the direct use of lanthanum metal as a reagent. Various unstable carbon species, such as alkyl radicals, o-quinodimethane, carbene, benzyne and alkylidene carbene, were easily generated by the reaction of organohalogen compounds with lanthanum metal. Carbonyl compounds were also reduced by lanthanum metal and the generated reducing species were widely used on the new carbon-carbon bond formations. The synthesis of organochalcogenides was successfully achieved by the reaction of dichalcogenides, alkyl halides, and lanthanum metal.
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  • Development of New Synthetic Methods for Heterocycles Utilizing 1,3-Dipoles
    Yutaka Ukaji, Takahiro Soeta
    2015 Volume 73 Issue 1 Pages 65-75
    Published: 2015
    Released on J-STAGE: February 20, 2015
    DOIhttps://doi.org/10.5059/yukigoseikyokaishi.73.65
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    Toward the preparation of heterocycles using 1,3-dipoles, the approaches have been generally limited to concerted 1,3-dipolar cycloaddition. A strategy consisted of a stepwise addition to 1,3-dipoles followed by cyclizaion could be an alternative pathway to synthesize of heterocycles. We have been interested in nucleophilic addition reactions to nitrones. In pursuing them, synthesis of heterocycles based on a new strategy of stepwise nucleophilic addition-cyclization and related transformations consisted of [1,3]-sigmatropic rearrangement was developed. A novel [5+1] cycloaddition reaction of C,N-cyclic-N’-acyl azomethine imines as 1,5-dipoles, 1,3-dipoles with extended conjugation, with isocyanides was explored. A [3+1+1] cycloaddition of azomethine ylides generated from aziridines in situ with isocyanides was also realized by the use of Lewis-acid catalyst. Furthermore, unprecedented ring enlargement reaction of the azomethine imines with sulfonium ylide was developed.
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