有機合成化学協会誌
Online ISSN : 1883-6526
Print ISSN : 0037-9980
ISSN-L : 0037-9980
77 巻 , 8 号
選択された号の論文の13件中1~13を表示しています
追悼
巻頭言
総説および総合論文
  • 芝原 文利
    2019 年 77 巻 8 号 p. 776-790
    発行日: 2019/08/01
    公開日: 2019/08/09
    ジャーナル 認証あり

    Previously, we accidentally found bidentate nitrogen-based ligands, in particular, 1,10-phenanthroline well work in palladium-catalyzed direct C-H bond arylation reaction of 5-membered heteroarenes. With this finding, we then explored catalytic utilities of the palladium/bidentate nitrogen-based ligand systems. Firstly, we extensively examined the utility for the direct C-H bond arylation of heteroarenes, and revealed that the catalytic system showed high activity for the reaction. A wide variety of C-H bonds on heteroarenes were arylated with the catalytic system. Importantly, the arylation at C4-position of azoles proceeded with high efficiency without any additives except base. A variety of multi-functionalized azole syntheses were also investigated, and we achieved a synthetic method of three different aryl groups introduced azoles from unfunctionalized azoles via simple sequential arylation reactions with a sole catalytic system. We also investigated the utilities of this catalytic system to oxidative coupling of terminal alkynes and azoles to result in good efficiency. One of the important features of this catalytic system is non-use of a phosphine ligand. With this feature, we achieved direct C-H bond arylation of thiocarbonylated compounds, that was hardly achieved because of the direct reaction of thiocarbonyl groups and phosphine ligands to result in loss of catalytic activity. To gain the insight of the reaction mechanism of this reaction with thiocarbonylated compounds, several control experiments were carried out.

  • 中村 巧, 岡田 めぐみ, 白川 誠司
    2019 年 77 巻 8 号 p. 791-799
    発行日: 2019/08/01
    公開日: 2019/08/09
    ジャーナル 認証あり

    Carbon dioxide (CO2) is recognized as an unfavorable industrial waste due to its greenhouse effect, and the reduction of CO2 emissions has become integral to the creation of a sustainable society. From a different point of view, however, CO2 is also recognized as an ideal C1 source for chemical synthesis because it is inexpensive, abundant, and nontoxic. In this context, the development of chemical transformations to useful compounds via the use of CO2 as a reactant has become a hot topic in the field of green sustainable chemistry. Among these transformations, the synthesis of cyclic carbonates from epoxides and CO2 has been the most extensively studied due to their high utility in industrial processes. Although a wide variety of metal catalysts and organocatalysts such as quaternary onium salts have been developed to promote this reaction, high temperature (>100 °C) and pressure (>10 atm) are often required to produce the products in satisfactory yields. Therefore, the development of catalysts that can be effective for this reaction under mild conditions continues to be highly desired. Herein, we summarize our catalytic approaches for the CO2 fixation under mild reaction conditions. Design concepts of our catalytic systems were discussed based on experimental results. Our catalytic system could also be applied to cyclic thiocarbonate synthesis by the use of carbon disulfide (CS2). The mechanisms for these two reactions are discussed based on the stereochemistry of cyclic carbonate and thiocarbonate products. Although these two reactions are similar, the reaction mechanisms are totally different.

  • 伊藤 繁和
    2019 年 77 巻 8 号 p. 800-812
    発行日: 2019/08/01
    公開日: 2019/08/09
    ジャーナル 認証あり

    The positive muon (µ+) is an elementary subatomic particle that is assigned as a member of lepton (spin I=1/2). Whereas muons are present in cosmic radiation, high-energy beam of proton from accelerators such as cyclotron and synchrotron produce almost fully polarized muons. The muon has one ninth of the proton mass (0.1126mp), and the polarized “ultralight proton” is applicable to similar spectroscopic analyses to electron-spin resonance (ESR) and nuclear magnetic resonance (NMR) without the alternative magnetic resonance techniques. In contact with matter, the positive muon captures an electron and become a muonium (Mu= [µ+e-]) that is a light isotope of hydrogen atom. The muoniums have been utilized for monitoring radical reactions of usual unsaturated organic molecules including benzene, alkene, alkyne, and ketone, and the corresponding radicals via muonium addition can be characterized by muon spin rotation/resonance/relaxation (µSR) spectroscopy. In this article, principles and usefulness of µSR for study of functional organic compounds are overviewed, and our recent findings on µSR measurements for the sterically encumbered 1,3-diphosphacyclobutane-2,4-diyl of singlet biradical are presented. A regioselective addition of muonium to the skeletal phosphorus atom in the 1,3-diphosphacyclobutane-2,4-diyl unit was characterized, which would be useful to understand the 4-membered heterocyclic molecular skeleton promoting the low-voltage p-type organic semiconductor behavior.

  • 瀨髙 渉, 稲垣 佑亮, 山口 健太郎
    2019 年 77 巻 8 号 p. 813-822
    発行日: 2019/08/01
    公開日: 2019/08/09
    ジャーナル 認証あり

    Rotation of the part of the molecules has been of interest in terms of artificial molecular rotors, which are one of the classes of molecular machines. We have been investigated macrocage molecules with a bridged π-electron system have been synthesized as “crystalline molecular gyrotops”, because the interior π-electron system can be rotate even in a crystal. These molecules were easily synthesized by applying silicon junctions that connect the π-electron rotor and three alkyl spokes. In this paper, chemistry of molecular gyrotops having phenylene, biphenylene, naphthalene-diyl, thiophene-diyl, and thiophenedioxide-diyl rotors have been described. Their cage structures were successfully confirmed by X-ray crystallography. Rotation of the rotor was investigated by solution and solid-state NMR spectroscopy. Some of them showed crystal-to-crystal phase transitions between static and dynamic states of the rotor, and their mechanisms were discussed.

  • 川瀬 毅, 井上 翔悟, 西田 純一
    2019 年 77 巻 8 号 p. 823-830
    発行日: 2019/08/01
    公開日: 2019/08/09
    ジャーナル 認証あり

    17H-Tetrabenzo [a, c, g, i] fluorene (TBF) as one of π-extended fluorene derivatives was first prepared about 60 years ago. Although π-extended fluorenes have been received vast attention from the field of organic electronics, TBF derivatives have not been well explored from the physicochemical points of view. Six 17,17- dialkylTBFs (methyl to n-hexyl) prepared from TBF show intense blue fluorescence in solutions. On the other hand, in the solid state, the fluorescent spectra and the quantum yields (ΦSD) vary with their alkyl chains. In particular, the ΦSD values of dialkylTBFs bearing n-propyl to n-hexyl groups are close to unity, while the fluorescence of parent TBF is almost quenched. Crystallographic analyses revealed that the π-π interactions of the TBF moieties probably play an important role in quenching the solid-state fluorescence. Quinone methide, and unsymmetrical and symmetrical fulvalene involving a TBF unit were synthesized. The electrochemical analyses reveal that these compounds exhibit high electron affinities. The substituent effect on optical properties of 3,14-diphenyl-17,17-di(n-pentyl)TBF derivatives bearing various substituents (H, CN, COOCH3, CHO, NO2, CH=C(CN)2) at 4-position of the phenyl groups were also synthesized and characterized. The diformyl, dinitro, and bis(dicyanoethenyl) derivatives show large solvatofluorochromism (CHO; ΔλFL=67 nm, NO2; ΔλFL=96 nm, CH=C(CN)2; ΔλFL=170 nm). Moreover, the diformyl derivative exhibits crystallochromism in fluorescence, and the dinitro and bis(dicyanoethenyl) derivatives display aggregation induced emission. The bis(dicyanoethenyl) derivative can also serve as a highly sensitive fluorescence “turn-on” probe for cyanide ion. The findings suggest that the ground-to-excited state electronic transition of these compounds should have intramolecular charge-transfer (ICT) character.

  • 坂本 渓太, 不破 春彦
    2019 年 77 巻 8 号 p. 831-840
    発行日: 2019/08/01
    公開日: 2019/08/09
    ジャーナル 認証あり

    Marine macrolide natural products are an important source of new chemotherapeutics and their lead compounds. Although in recent years significant advances of NMR instruments have enabled structure determination of natural products at sub-microgram scale, complex macrolides are still challenging targets for structure assignment because many of them contain multiple stereogenic centers along conformationally flexible macrocyclic backbone. Accordingly, total synthesis plays a conclusive role in structure determination of complex macrolides. Furthermore, biological assessment of synthetic material is indispensable for validating the biological activity/potency of natural products. In this paper, we delineate our total synthesis of a marine macrolide iriomoteolide-2a as a case study that demonstrates the significance of total synthesis in natural product chemistry.

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