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| 1.
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Fujii, Tozo ; Ohba, Masashi ; Kawamura, Hitoshi ; Nakashio, Yoshiyuki ; Honda, Kei ; Matsubara, Satoshi
概要:
Both enantiomers [(1'R)-6 and (1'S)-6] of N6-(1,3-dimethyl-2- butenyl)adenine and their 9-β-D-ribofuranosides [(1''R)-16
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and (1''S)-16] have been synthesized for the first time from both enantiomers of alanine (15) in nine steps. These aglycones and nucleosides, together with N6-(3- methyl-2-butenyl)adenine (5) and its 9-β-D-ribofuranoside (18) as well as 9- β-D-ribofuranosyl-cis-zeatin (20) and 9-(2-deoxy-β-D-ribofuranosyl)-cis- zeatin (19), were tested for cytokinin activity in the tobacco callus bioassay. The order of their activity was 5> (1'R)-6 > (1''R)-16≃18>(1'S)- 6>(1''S)-16>20>19. The bioassay results are compared with those obtained previously for the derivatives modified analogously in the N6-substituent in the cis- and trans-zeatin series.
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| 2.
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Fujii, Tozo ; Yoshifuji, Shigeyuki ; Yoshida, Kiyoshi ; Ohba, Masashi ; Ikegami, Shiro ; Kirisawa, Makoto
概要:
The alkaline ferricyanide oxidation of the quaternary pyridinium salts (Ia-g) furnished pairs of the isomeric 2-pyridones (IIa-g) and 6-pyridones (IIIa-g) in good total yields. In all cases, the oxidation at the 2-position was much
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favored over that at the 6-position. The effect of the aryl group in the N-aralkyl chain on the orientation of the oxidation seemed to be negligibly small regardless of the number of the methylene groups separating the aryl group from the nitrogen. The extent of the 6-oxidation was slightly increased as the alkyl group at the 3-position was changed from the methyl to the ethyl group. The nuclear magnetic resonance spectra of these pyridones were measured in deuteriochloroform, carbon tetrachloride, and benzene-d_6. On the basis of the results summarized in Tables III-VI, the effects of the aryl group and the number of the methylene groups in the N-substituent on the chemical shifts for the pyridone-ring and neighboring group protons are discussed.
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| 3.
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Fujii, Tozo ; Ohba, Masashi ; Ali, Esahak ; Suzuki, Hitoshi ; Sakaguchi, Jun
概要:
The synthesis of (±)-9-demethylprotoemetinol [(±)-3d] was accomplished by LiAlH_4 reduction of the tricyclic ester (±)-5
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and subsequent debenzylation of the resulting tricyclic-alcohol (±)-10. Acetylation of (±)-3d with acetic anhydride and pyridine gave the diacetate (±)-11. The same sequence of reactions starting with (-)-5 afforded (-)-9-demethylprotoemetinol [(-)-3d] and the diacetate (-)-11 through (-)-10. Parallel synthetic routes starting with the isomeric tricyclic esters (±)-9 and (-)-9 produced (±)- and (-)-10-demethylprotoemetinols [(±)-4d and (-)-4d] and the corresponding diacetates [(±)-13 and (-)-13] through (±)-12 and (-)-12, respectively. The correctness of the structure and absolute stereochemistry of an Alangiutn alkaloid inferred to be 10-demethylprotoemetinol was confirmed by a direct comparison of its diacetate with synthetic (-)-13.
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| 4.
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Fujii, Tozo ; Yoshifuji, Shigeyuki ; Hatanaka, Yasumaru ; Yoshida, Kiyoshi ; Ohba, Masashi ; Yamada, Koichiro ; Ohkuma, Mihoko ; Shinoda, Hirotaka ; Mizuno, Denichi
概要:
Seventy-four compounds related to lactams and pyridones were synthesized and their anti-tumor activity was examined using Ehrlich carcinoma cells. 4-(2-Piperidyl) butyric acid hydrochloride was found to have some anti-tumor
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effect on the solid type of Ehrlich carcinoma cells, but no other substances were found to be effective. Correlation between the anti-tumor activity and structure of the tested compounds still remains uncertain.
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| 5.
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Fujii, Tozo ; Ohba, Masashi
概要:
The racemic synthesis of the Alangium lamarckii alkaloid 10-demethyltubulosine (2) has been accomplished for the first t
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ime via a "lactim ether route, "which included the intermediates (±)-7,(±)-8,(±)-10,and (±)-9. The 1'α-H isomers (±)-12 and (±)-11 were also obtained through this synthetic route. The assignments of the configuration at C-1'of (±)-2,(±)-9,(±)-11,and (±)-12 were based on four criteria, namely, the ratio of products from the catalytic reduction of (±)-10,thin-layer chromatographic mobility, and ^1H and ^<13>C nuclear magnetic resonance spectral features. The identity of synthetic (±)-2 with (-)-demethyltubulosine from A. lamarckii unequivocally established the structure of this alkaloid.
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| 6.
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Fujii, Tozo ; Ohba, Masashi ; Tachinami, Tsuyoshi ; Miyajima, Hisae
概要:
The first total synthesis of ochropposinine (1), a Neisosperma and Ochrosia alkaloid, has been accomplished in the form
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of a racemic modification by means of an initial coupling of the lactim ether (±)-3 with 5 and succeeding steps proceeding through the intermediates (±)-7,(±)-8,(±)-9,(±)-10,and (±)-11. A parallel synthetic route starting with (+)-3 produced the chiral target molecule (-)-1 via the intermediates (+)-7,(+)-8,(+)-9,10,and (-)-11. As a result, the absolute configuration of ochropposinine has been unequivocally established to be that represented by formula (-)-1.
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| 7.
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Fujii, Tozo ; Ohba, Masashi ; Akiyama, Shigeaki
概要:
In boiling 2.5 N solution of KOH in 40% (w/w) aqueous EtOH, the lactams (±)-5a, b, d were hydrolyzed to an extent of 75-
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98% within 8-20 h, attaining equilibrium with the corresponding ω-amino acid derivatives (±)-6a, b, d. The potassium salt (±)-8,generated in situ from the translactam acid (±)-7,was equilibrated with the ring-opened product (±)-6f and the recyclized cis isomer (±)-5f in a ratio of 57 : 15 : 28 within ca. 45 h under similar reaction conditions. The cis-N-(2-arylethyl) analog (-)-9 was converted into the trans-lactam acid (+)-13,a key synthetic precursor for the 8-hydroxy-9,10-dimethoxybenzo [a] quinolizidine-type Alangium alkaloids, through application of such alkaline hydrolytic cis-trans equilibration followed by debenzylation.
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| 8.
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Fujii, Tozo ; Ohba, Masashi
概要:
With the aim of establishing the structure of the Alangium alkaloid desmethylpsychotrine, stereospecific syntheses of tw
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o alternative structures, (±)-9-demethylpsychotrine (1) and (±)-10-demethylpsychotrine (2), have been achieved through a"lactim ether route."The synthesis of (±)-1 started with an initial condensation of the lactim ether 6,derived from the translactam ester 5,with 3-benzyloxy-4-methoxyphenacyl bromide (7a) and proceeded through the intermediates 8a, 9a, 10c, 10a, 11a, 12a, 13a, 14a, and 15a. A parallel sequence of conversions starting with 6 and 4-benzyloxy-3-methoxyphenacyl bromide (7b) produced (±)-2. The ^<13>C nuclear magnetic resonance spectra of (±)-1 and (±)-2 confirmed their endocyclic double bond structure in the dihydroisoquinoline moiety. Spectral comparison of (±)-1 and (±)-2 with natural desmethylpsychotrine suggested formula 1 to be the most likely structure of this alkaloid.
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| 9.
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Fujii, Tozo ; Yoshida, Kiyoshi ; Ohba, Masashi ; Yoshifuji, Shigeyuki
概要:
The mercuric acetate-(ethylenedinitrilo) tetraacetic acid oxidation of 1-(3,4-dimethoxyphenyl)-2-(3-substituted piperidino) ethanols (7c-f), which carry the n-butyl, isopropyl, benzyl, and phenyl group as the 3-substituent in
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the piperidine ring, has been found to produce the corresponding 2- (8c-f) and 6-piperidones (12c-f) in good yields in ratios of 41 : 59,29 : 71,26 : 74,and 15 : 85. It is suggested that the 3-substituents exert both steric and electronic effects. The structures of the lactam alcohols (8c-f, 12c-f) have been confirmed by the chemical correlation with the known pyridones (11c-f, 15c-f) through the lactams (10c-f, 14c-f). The starting piperidinoethanols (7c-f) have been synthesized from the 3-substituted pyridines (5c-f) by quaternization with 3,4-dimethoxyphenacyl bromide followed by catalytic and sodium borohydride reductions.
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| 10.
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Fujii, Tozo ; Ohba, Masashi ; Yoshifuji, Shigeyuki ; Kirihara, Makoto
概要:
In the alkaline ferricyanide oxidation at 32°of 3-substituted 1-(3,4-dimethoxyphenethyl) pyridinium bromides (type 3), t
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he hydroxymethyl, N, N-dimethylaminomethyl, carbamoyl, and 1,1-ethylenedithioethyl groups at the 3-position have been found to orient the oxidation to both the 2-(type 4) and the 6-position (type 5) in ratios of 70 : 30,26 : 74,50 : 50,and 4 : 96. The carboxyl or 1,1-ethylenedioxyethyl group at the 3-position has oriented the oxidation to the 6-position exclusively, and possible factors in determining the regioselectivity in the ferricyanide oxidation of the 1,3-disubstituted pyridinium salts are discussed. For preparation of additional pyridone derivatives, 1-(3,4-dimethoxyphenethyl)-5-carboxy-2(1H)-pyridone (5d) was esterified with methanolic hydrogen chloride to the methyl ester (5h), and 1-(3,4-dimethoxyphenethyl)-5-(1,1-ethylenedioxyethyl)-2 (1H)-pyridone (5e) was converted into the methyl ketone (5i) by acid hydrolysis. The structures of the pyridones (4a, b, c, f, 5a-i) thus prepared have assigned on the basis of their ultraviolet, infrared, and nuclear magnetic resonance spectra.
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