研究者詳細 - 宮本　和範

宮本　和範（ミヤモト　カズノリ）

Miyamoto, Kazunori

写真a

所属（所属キャンパス）: 薬学部薬科学科（芝共立）

職名: 教授

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Estimation Method of Whiteline Intensity of Platinum Compounds at L3 Edge XANES and the Oxidation Number Using a Laboratory-type Spectrometer

Yamamoto T., Miyamoto K.

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan 110 （ 12 ） 973 - 980 2024年09月

ISSN 00211575

　概要を見る

Pt L3 edge XANES spectra of various kinds of platinum compounds were recorded using a laboratory-type X-ray absorption spectrometer. In order to investigate precision and the accuracy for oxidation state analysis of platinum species with a simple method, the white line intensity was evaluated by least squares fitting using four kinds of profile functions (Gaussian, Lorentzian and two types of pseudo-Voigt functions) and one arctangent function for continuum state. Differences in estimated values and the deviations depending on the type of profile function adopted were discussed. White line intensity could be determined easily and reproducibly using pseudo-Voigt function where a fraction of Lorentzian function is variable. The relationship between oxidation number of Pt compounds and white line area obtained by pseudo-Voigt method are the most preferable. The height of the white line for divalent compounds varies greatly in some cases, and then it is inappropriate to apply the height to estimation of the oxidation number of unknown samples. The changes in platinum species of silica supported Pt(NH3)4Cl2 of a catalyst precursor during air calcination was examined by in-situ XANES. The platinum species exist as divalent species up to 473 K, and changed to zero-valent between 473 and 573 K. The present in-situ laboratory XAFS experiment and the oxidation state analysis is consistent with SR XAFS studies by other research group.
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Room-temperature synthesis of m-benzyne

Koyamada K., Miyamoto K., Uchiyama M.

Nature Synthesis 3 （ 9 ） 1083 - 1090 2024年09月

　概要を見る

For over a century, scientists have been fascinated by the unique electronic, structural and bonding properties of the three isomers of benzyne, a highly reactive organic intermediate derived from benzene by removing two hydrogen atoms. Although o- and p-benzynes have been extensively studied following the establishment of reliable synthetic methods to prepare them, m-benzyne in the ground state has remained experimentally inaccessible. We report herein the room-temperature and atmospheric-pressure synthesis of m-benzyne in solution. Experimental and theoretical investigations revealed that owing to the inner bond inside the benzene ring between C1 and C3 atoms, m-benzyne behaves as a potent electrophile with a Mayr’s electrophilicity parameter E of around −2 but shows weak free-radical character. The bonding appears similar to the inverted σ-bond, the so-called charge-shift bond, in [1.1.1]propellane. By utilizing the unique bonding character of m-benzyne, we established halogenations and C–N and C–C coupling reactions, as well as a successive m-benzyne generation and trapping sequence that provides access to 1,3,5-trisubstituted benzenes. (Figure presented.)
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Transition-Metal-Free Thioboration of Terminal Alkynes

Matsuyama T., Ishida H., Wang C., Miyamoto K., Nakajima M., Toriumi N., Nagashima Y., Uchiyama M.

JACS Au 2024年

　概要を見る

We present a new type of elementoboration reaction, the thioboration of terminal alkynes. This method enables highly controllable regio-/stereo-/chemoselective cis- and trans-thioboration on demand, affording synthetically versatile and densely functionalized vinyl boron/vinyl sulfide derivatives in a straightforward manner without the need for a transition-metal catalyst.
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Dearomative triple elementalization of quinolines driven by visible light

Ishigaki S., Nagashima Y., Yukimori D., Tanaka J., Matsumoto T., Miyamoto K., Uchiyama M., Tanaka K.

Nature Communications 14 （ 1 ） 2023年12月

　概要を見る

Organoboron and organosilicon compounds are used not only as synthetic building blocks but also as functional materials and pharmaceuticals, and compounds with multiple boryl and silyl groups are beginning to be used for these purposes. Especially in drug discovery, methodology providing easy stereoselective access to aliphatic nitrogen heterocycles bearing multiple boryl or silyl groups from readily available aromatic nitrogen heterocycles would be attractive. However, such transformations remain challenging, and available reactions have been mostly limited to dearomative hydroboration or hydrosilylation reactions. Here, we report the dearomative triple elementalization (carbo-sila-boration) of quinolines via the addition of organolithium followed by photo-boosted silaboration, affording the desired products with complete chemo-, regio-, and stereoselectivity. The reaction proceeds via the formation of silyl radicals instead of silyl anions. We also present preliminary studies to illustrate the potential of silaboration products as synthetic platforms.
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Mechanistic Analysis of Stereodivergent Nitroalkane Cyclopropanation Catalyzed by Nonheme Iron Enzymes

Ushimaru R., Cha L., Shimo S., Li X., Paris J.C., Mori T., Miyamoto K., Coffer L., Uchiyama M., Guo Y., Chang W.C., Abe I.

Journal of the American Chemical Society 145 （ 44 ） 24210 - 24217 2023年11月

ISSN 00027863

　概要を見る

BelL and HrmJ are α-ketoglutarate-dependent nonheme iron enzymes that catalyze the oxidative cyclization of 6-nitronorleucine, resulting in the formation of two diastereomeric 3-(2-nitrocyclopropyl)alanine (Ncpa) products containing trans-cyclopropane rings with (1′R,2′R) and (1′S,2′S) configurations, respectively. Herein, we investigate the catalytic mechanism and stereodivergency of the cyclopropanases. The results suggest that the nitroalkane moiety of the substrate is first deprotonated to produce the nitronate form. Spectroscopic analyses and biochemical assays with substrates and analogues indicate that an iron(IV)-oxo species abstracts proS-H from C4 to initiate intramolecular C-C bond formation. A hydroxylation intermediate is unlikely to be involved in the cyclopropanation reaction. Additionally, a genome mining approach is employed to discover new homologues that perform the cyclopropanation of 6-nitronorleucine to generate cis-configured Ncpa products with (1′R,2′S) or (1′S,2′R) stereochemistries. Sequence and structure comparisons of these cyclopropanases enable us to determine the amino acid residues critical for controlling the stereoselectivity of cyclopropanation.
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