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図書
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Tadeusz Skorupski
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図書
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寺田幸代[著]
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edited by Ellen M. Raven and Helga I. Lasschuijt
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論文
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Kimura, Rumi ; Nagano, Tanemasa ; Kinoshita, Hideki
概要:
Ethyl N-Boc- and N-Z-α-tosylglycinates were reacted with a variety of aldehydes in the presence of tributylphosphine and
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a base to afford the corresponding α,β-didehydroamino acid derivatives with high (Z)-selectivity in good yields. Moreover, ethyl (4S)- and (4R)-2-(N-Boc-amino)-4,5-isopropylidenedioxy-2-pentenoates prepared by the present method were converted to (2S, 4S)- and (2R, 4R)-4-hydroxyprolines, respectively.
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edited by IWA Task Group on Mathematical Modelling for Design and Operation of Biological Wastewater Treatment
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par René Antoine Gauthier et Jean Yves Jolif
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| 7.
その他 |
その他
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植物地理・分類学会 ; The Society for the Study of Phytogeography and Taxonomy
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論文
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Kohtani, Shigeru ; Sugiyama, Masahide ; Fujiwara, Yoshihisa ; Tanimoto, Yoshifumi ; Nakagaki, Ryoichi
概要:
Magnetic field effects (MFE) on asymmetric photolysis involving a biradical intermediate have been investigated on a kin
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etic model where an intersystem crossing (ISC) of the intermediate is taken into account. Changes in the enantiomeric excesses (ee) of chiral substances with circularly polarized light (CPL) irradiation have been simulated, and the necessary conditions for observing the MFE were obtained. The asymmetric photolysis of racemic 2-phenylcycloalkanones (2-PCAs) with CPL has been carried out in both the presence and absence of a magnetic field. Since the anisotropy g factors of 2-PCAs are considerably large, the CPL-induced ee are achieved to a few percent after 90% decomposition though the MFE are not observed. The photolysis mechanism of 2-PCAs in an air-saturated solution has been also clarified. Triplet acyl–benzyl biradicals, formed via photochemical α-cleavage of 2-PCAs, react with O2 dissolved in the solution and result in the formation of acetophenone and alkenoic acids. The bimolecular reactions are diffusion-controlled and the rates are comparable to those of ISC to the singlet biradicals for all 2-PCAs. The recombination yields of the biradicals are sufficiently large. However, the biradical ISC rate shows little magnetic field dependence, which explains the absence of the MFE in this asymmetric photolysis.
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| 9.
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図書
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David Eisenbud ... [et al.] (eds.)
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論文
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Itaya, Taisuke ; Iida, Takehiko ; Natsutani, Itaru ; Ohba, Masashi
概要:
The relationship between the product patterns and the configurations of 1,2-cycloheptane- and 1,2-cyclooctanediols 9 in
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the cyclocondensations with oxalyl chloride in the presence of tricthylamine at 0°C has been shown analogous to that obtained for 1,2-disubstituted acyclic ethylene glycols 1: cis-1,2-cyclooctanediol (9f) produced the cyclic oxalate 14f as the major product, while trans-1,2-cycloheptanediol (9e) and trans-1,2-cyclooctanediol (9g) formed the cyclic carbonates 12e, g as the major products. On the other hand, the cyclic oxalates 14a-d were formed as the major products from 1,2-cyclopentane- and 1,2-cyclohexanediols regardless of the configuration. These results can be accounted for by assuming the boat-like transition states for cyclizations of the half esters of comparatively rigid five- and six-membered diols 9a-d. The cyclic oxalates 14a, c may be directly formed through the resulting tetrahedral intermediates from cis-diols (9a, c), and the cyclic carbonates 12a, c as the minor products after ring inversion of the tetrahedral intermediates. The tetrahedral intermediates from the trans-isomers 9b,d cannot undergo ring inversion, producing no traces of the cyclic carbonates 12b,d. © 2002 Pharmaceutical Society of Japan.
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