京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21378号 / 農博第2302号 / 新制||農||1070(附属図書館) / 学位論文||H30||N5151(農学部図書室) / 京都大学大学院農学研究科食品生物科学専攻 / (主査)教授 橋本 渉, 教授 入江 一浩, 教授 保川 清 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Flavonols are hydroxyl-substituted flavonoids and naturally occur as secondary metabolites in plants. Several studies have discovered extensive medicinal properties of flavonols. The present work reports on structural and functional investigation of the B ring substituted flavonols based on spectroscopic and electrochemical techniques. The purpose of this study is to determine the influence of the B ring substitutions on the hydrogen bonding interactions, the electronic effects in ruthenium complexes and the Al3+ chelation of B ring substituted flavonols. The electronic effects of the B rings were changed by introducing methyl, methoxy and nitro groups at position 4ʹ on the B ring. The 3ʹ-methyl substitution was performed in order to increase the electronic density of the B ring via inductive effects. The 2ʹ-methyl and 2ʹ, 6ʹ-dimethyl substitutions increased the steric effects around the inter-ring bond between the B and the C rings, and the B ring was highly deconjugated from the AC rings. The intramolecular hydrogen bonding distances at 3-hydroxy-4-carbonyl units of the B ring substituted flavonols were elongated while the dihedral angles between the B and AC increased. Strong intermolecular hydrogen bonding interactions were also observed in the crystal structures of 4ʹ-methylflavonol, 4ʹ-methoxyflavonol, 4ʹ-nitroflavonol and 2ʹ,6ʹ-dimethylflavonol. Furthermore, several crystal packing patterns were observed, and it is postulated that dihedral angles and intramolecular hydrogen bonding distances are both affected by the intermolecular hydrogen bonding interactions and the crystal packing forces. In addition, the ruthenium complexes of B ring substituted flavonols were synthesized and characterized by spectroscopic and electrochemical techniques. B ring substitution effects were minimal in IR spectroscopy and X-ray crystallography. The levels of the conjugation of the rutheniumlavonolate complexes were demonstrated by electronic absorption spectra recorded in methanol at room temperature. The most positive oxidation potential was obtained with the electron withdrawing nitro group substitution, and the electron donating substitutions resulted in more negative oxidation potentials. The spectroscopic investigation of the complex formation of Al(III) with flavonols and 3-hydroxychromone is described. The stoichiometric composition and stability constants are also given. The comparison of the results obtained from Al(III) chelation shows significant effects of the B ring substitutions.

Single crystal X-ray crystallography instructional materials were developed using a variety of compounds including sugar, Epsom salt, pyrite, copper(II) acetate, and rhodium(II) acetate. Rhodium(II) acetate was reacted with a variety of functionalized benzonitriles, and when crystals were obtained, characterized using single crystal X-ray crystallography. Rhodium(II) acetate with adducts of 4-nitrobenzonitrile and 4-(dimethylamino)benzonitrile were also characterized using proton NMR spectroscopy and Fourier Transform Infrared Spectroscopy. Rhodium(II) acetate with adducts of 4-(dimethylamino)benzonitrile was used as a catalyst in a proof-ofconcept reaction to determine if it acts as a catalyst in cyclopropanation reactions. Further, the new rhodium(II) acetate dinitrile compounds were investigated to determine if they would yield a different product ratio of cyclopropanes than that from the model Rh=CRR' mediated reaction between ethyl diazoacetate and styrene. The resulting cyclopropanation products were characterized using Gas Chromatography Mass Spectrometry. Preliminary experimental results yielded a trans- to cis-2-phenylcyclopropanecarboxylate ratio of 40:60.

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