- The development and use of a general route to brassinolide, its biosynthetic precursors, metabolites and analogues
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A new method for the construction of steroid side chains through the addition of lithium salts of dithianes to a C-22 aldehyde was developed. An efficient one-pot procedure for the preparation of a suitable C-22 aldehyde from commercial epibrassinolide in three steps in 86% isolated yield was described. Enantioselective hydroxymethylation of isovaleraldehyde and Kulinkovich cyclopropanation of silylated Roche esters were used as key steps for the dithiane syntheses. The method was applied for the preparation of brassinolide, its biosynthetic precursors and metabolites. In addition, a number of brassinosteroids with a double bond in the side chain were prepared as precursors for tritiated derivatives for biosynthetic studies.
- Hurski,Ermolovich,Zhabinskii,Khripach
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p. 1446 - 1452
(2015/01/30)
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- A general approach to synthesis of labeled brassinosteroids: Preparation of [25,26,27-2h7]brassinolide with 60% isotopic purity from the parent brassinolide
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From brassinolide (BL) 1, [25,26,27-2H(n)]BL 10 was synthesized in 5 steps including C-25 hydroxylation, dehydration and catalytic deuteriogenation. In direct oxy-functionalization of tetra-O-acetyl BL 2 with methyl(trifluoromethyl)dioxirane leading to 25-hydroxyl compound 3, 14- hydroxyl, 25-hydroxy-15-oxo and 14,25-dihydroxyl derivatives, 4, 5 and 6, were newly identified; the catalytic deuteriogenation of Δ(25(26))-BL 8 using 5% palladium-on-charcoal resulted in abundant incorporation of deuterium atoms to give 10 with 60% isotopic purity of [25,26,27-2H7]BL.
- Seto, Hideharu,Fujioka, Shozo,Koshino, Hiroyuki,Yoshida, Shigeo,Watanabe, Tsuyoshi,Takatsuto, Suguru
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p. 7525 - 7528
(2007/10/03)
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- STEREOCONTROLLED SYNTHESIS OF THE BRASSINOLIDE SIDE CHAIN VIA A PYRANONE DERIVATIVE
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A new method for assembling the brassinolide side chain from 20-carboxaldehyde 2 was developed via the stereoselective construction of the pyranone moiety as key steps.
- Kametani, Tetsuji,Keino, Katsuyuki,Kigawa. Masaharu,Tsubuki, Masayoshi,Honda, Toshio
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p. 3141 - 3142
(2007/10/02)
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- Synthesis and biological activity of brassinolide and its 22 beta, 23 beta-isomer: novel plant growth-promoting steroids.
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Brassinolide (2 alpha, 3 alpha, 22 alpha, 23 alpha-tetrahydroxy-24 alpha-methyl -B-homo-7-oxa-5 alpha-cholestan-6-one), a novel plant growth-promoting steroid isolated from rape pollen, and its hitherto unknown 22 beta, 23 beta-isomer were synthesized from a C-24 epimeric 60:40 mixture of 22-dehydroxampesterol (24 alpha-methyl) and brassicasterol (24 beta-methyl) from oysters. The method of synthesis favored the formation of the 22 beta, 23 beta-isomer by better than 4:1. Comparative plant growth-promoting capabilities of brassinolide, both natural and synthetic, and its three side chain cis-glycolic isomers in the bean second internode bioassay showed that the natural and synthetic brassinolides were equally active and caused splitting of the internode at the 0.1 microgram level. The least active was the 22 beta, 23 beta-isomer of brassinolide. The isomers with the 22 alpha, 23 alpha and 24 alpha, and the 22 beta, 23 beta and 24 beta configurations were highly active and were required at about 10 times the concentration of brassinolide to cause the same physiological response. In the bean first internode bioassay, an auxin-induced growth test system which employs isolated bean plant segments, the isomer with 22 beta, 23 beta and 24 beta configuration caused a greater response than brassinolide. Two of the four tetrahydroxy ketones obtained in the synthesis of the isomers were also active in both assays.
- Thompson,Mandava,Meudt,Lusby,Spaulding
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p. 567 - 580
(2007/10/02)
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