京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19914号 / 理博第4214号 / 新制||理||1605(附属図書館) / 33000 / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 島川 祐一, 教授 有賀 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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Halogen bonding to phosphorus atoms remains uncommon, with relatively few examples reported in the literature. In part 1 of the thesis, the preparation and investigation of the cocrystal (dicyclohexylphenylphosphine)(1,6-diiodoperfluorohexane) by X-ray crystallography and solid-state multinuclear magnetic resonance spectroscopy is described. The crystal structure features two crystallographically unique C-I···P halogen bonds (dI···P = 3.090(5) Å, 3.264(5) Å) and crystallographic disorder of one of the 1,6-diiodoperfluorohexane molecules. The first of these is the shortest and most linear I···P halogen bond reported to date. 13C, 19F, and 31P magic-angle spinning solid-state NMR spectra are reported. A 31P chemical shift change of -7.0 ppm in the cocrystal relative to pure dicyclohexylphenylphosphine, consistent with halogen bond formation, is noted. This work establishes iodoperfluoroalkanes as viable halogen bond donors when paired with phosphorus acceptors, and also shows that dicyclohexylphenylphosphine can act as a practical halogen bond acceptor. In part 2 of the thesis, computational work was done on nuclides of atoms which engage in the strongest halogen bonds (iodine, bromine, chlorine) that are all quadrupolar (spin I > ½). Previous group work reported extensive experimental NMR and NQR data relating 35/37Cl, 79/81Br, and 127I quadrupolar coupling information to local molecular structure in halogen bonded systems. Here, we make use of a new parameter, the valence p-orbital population anisotropy (VPPA), reported by Rinald and Wu, to increase our understanding of the origins of the electric field gradients (EFG) in halogen-bonded systems. Computations on model and real halogen-bonded cocrystalline systems using standard hybrid DFT methods are used to generate p-orbital populations and to compute the VPPA. We discuss the utility of the VPPA, and hence the EFG, as a tool to assess the ability of particular donors to engage in halogen bonds.

<p>  </p> <p>Alkyl radicals are powerful intermediates for the generation of carbon-carbon bonds, which play an indispensable role in the synthesis of natural products, pharmaceuticals, and pesticides. Traditionally, there are two main methods for the generation of alkyl radicals. The first is C-H bond functionalization via hydrogen-atom-transfer (HAT). HAT processes have been used as an effective approach for selectively activating C-H bonds via radical pathways. The other strategy to explore the generation of alkyl radicals is C-X bond functionalization via halogen-atom-transfer (XAT). Alkyl halides are one of the largest classes of building blocks in synthesis and they can be obtained from the corresponding alcohols. The most straightforward and effective way to form such alkyl radicals is the direct homolytic cleavage of C-X bonds. In past decades, photoredox catalysis has emerged as a powerful and greener tool for the synthesis of radicals under mild reaction conditions, which has brought tremendous attention. Although remarkable success has been made in this field, some methods still require costly transition metal catalysts or toxic reagents. Herein, we display a series of visible light-induced approaches under transition-metal free conditions or using earth-abundant metals. These novel photo-induced transformations and corresponding mechanistic work will be discussed in the following order:</p> <p>We will first present our work on metal-free visible-light-promoted C(sp3)-H functionalization of aliphatic cyclic ethers using trace O2.  This reaction uses a trace amount of aerobic oxygen as the sole green oxidant under blue light at room temperature to achieve the synthesis of sulfone and phosphate derivatives in good to excellent yields using cyclic ethers and vinyl sulfones. Then, we report on a photo-induced C(sp3)-H chalcogenation of amide derivatives and ethers via a ligand-to-metal charge-transfer. This reaction converts secondary and tertiary amides, sulfonamides, and carbamates into the corresponding amido-<em>N,S</em>-acetal derivatives in good yields, using an earth abundant metal catalyst under mild conditions.</p> <p>Finally, we present a photoredox polyfluoroarylation of alkyl halides via halogen atom transfer. This method converts primary, secondary, and tertiary unactivated abundant alkyl halides into the corresponding polyfluoroaryl compounds in good yields and has good functional group compatibility.</p>

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No / The Raman and electron impact mass spectra of synthetic indigo and its four 6,6'-dihalogeno analogues are reported and discussed. The influence of varying the halogen on these Raman spectra is considered. Particular emphasis is laid on distinguishing indigo from 6,6'-dibromoindigo and differentiating between the dihalogenocompounds, so as to develop protocols for determining whether artefacts are coloured with dyes of marine or terrestrial origin and whether such artefacts are dyed with genuine Tyrian Purple or with dihalogenoindigo substitutes that do not contain bromine. The value of even low resolution electron impact mass spectrometry in a forensic context as a means of identifying authentic 6,6'-dibromoindigo and distinguishing it from its dihalogenoanalogues is emphasised.