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| 1.
論文 |
論文
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Fujii, Tozo ; Ohba, Masashi ; Kawamura, Hitoshi ; Haneishi, Tsuyoshi ; Matsubara, Satoshi
概要:
(1'S)-1'-Methyl-cis-zeatin [(1'S)-2] and its 9-β-D-ribofuranoside [(1'S)- 4] were synthesized from L-alanine through [S-
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(Z)]-4-amino-2-methyl-2- penten-1-ol ethanedioate [(S)-3]. Condensations of 2-hydroxy-6- methylthiopurine (16) with the trans-isomeric amine salt [(S)-15], its enantiomer [(R)-15], and the racemic modification [(±)-15] furnished (1'S)- , (1'R)-, and (±)-2-hydroxyl-1'-methyl-trans-zeatins (6), respectively. A similar condensation of 16 with methylamine yielded 2-hydroxy-N6- methyladenine (7). These adenine derivatives were tested for cytokinin activity in the tobacco callus bioassay, and the order of their activity was (1'R)-6>(±)-6>(1'S)-2>7; on the other hand, (1''S)-4 and (1'S)-6 were completely inactive at 0.1-100 μM and 0.01-10 μM concentrations, respectively. As a result of the above syntheses of (1'R)-6, (1'S)-6, (±)- 6, and 7, the gross structures of a marine green alga cytokinin and of a blue coral cytokinin were established to be 6 and 7, respectively.
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| 2.
論文 |
論文
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Ohba, Masashi ; Haneishi, Tsuyoshi ; Fujii, Tozo
概要:
Synthesis of (±)-(4aα,6α,7α,7aα)-hexahydro-6-hydroxy-7- methylcyclopenta[c]pyran-3(1h)-one [(±)-1] has been achieved thr
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ough an 8- step route starting from 6,7-dihydrocyclopenta-1,3-dioxin-5(4H)-one (4). The identities of synthetic (±)-1 with abelialactone, Aglykon A1, and isoboonein permitted the unequivocal assignment of this common structure and the relative stereochemistry to these cyclopentano-monoterpene lactones.
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| 3.
論文 |
論文
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Ohba, Masashi ; Haneishi, Tsuyoshi ; Fujii, Tozo
概要:
Formal syntheses of (±)-boschnialactone (5) and three cyclopentano-monoterpene lactones [i.e., (±)-(iridomyrmecin (6), (
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±)-isoiridomyrmecin (7), and (±)-allodolicholactone (8)] have been accomplished in the form of the syntheses of 2-(methoxymethyl)-3-methyl-2-cyclopenten-1-one (11) and (±)-(4aα,7α,7aα)-hexahydro-7-methylcyclopenta[c]pyran-3(1H)-one (19), respectively, starting from 6,7-dihyd;ocyclopenta-1,3-dioxin-5(4H)-one (2). A synthesis of (±)-isodehydroiridomyrmecin (9) has also been achieved through a route including direct substitution of the hydroxy group of 2-(tert-butyldimethylsilyloxymethyl)-3- methyl-2-cyclopenten-1-ol (22) with 1-(tert-butyldimethylsilyloxy)-1-methoxyethene (23) as a key step.
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