A new efficient synthesis of GR24 and dimethyl A-ring analogues, germinating agents for seeds of the parasitic weeds Striga and Orobanche spp.
A new efficient synthesis of GR24 and dimethyl A-ring analogues, germinating agents for seeds of the parasitic weeds Striga and Orobanche spp.
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DOI：
10.1016/j.tet.2010.06.072
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发表时间：
2010-08-28
期刊：
影响因子：
2.1
通讯作者：
Zwanenburg, Binne
中科院分区：
文献类型：
--
作者：
Malik, Heetika;Rutjes, Floris P. J. T.;Zwanenburg, Binne
报道了一种高效高产的合成发芽刺激物GR24(5)及其a环二甲基取代类似物30-32的制备方法。第一步是苯甲醛9-11与琥珀酸二甲酯的斯托贝缩合。随后酯的转位和双键的还原为分子内Friedel-Crafts酰化提供了构建块15-17。abc -内酯22-25由-酮酯18-21经皂化、硼氢化钠还原、酸催化内酯化制备而成。内酯与d环的偶联是通过甲酰化和随后的溴丁烯内酯8处理来完成的，得到GR24及其二甲基类似物。生物测定表明，二甲基类似物的活性略低于GR24本身。(C) 2010 Elsevier Ltd.版权所有。
An efficient and high yielding preparation for the synthetic germination stimulant GR24 (5) and its A-ring dimethyl-substituted analogues 30-32 has been described. The first step involves a Stobbe condensation of benzaldehydes 9-11 with dimethyl succinate. Subsequent transposition of the ester and reduction of the double bond provides the building blocks 15-17 for an intramolecular Friedel-Crafts acylation. ABC-lactones 22-25 are prepared from gamma-keto esters 18-21 by saponification, subsequent reduction with sodium borohydride followed by acid-catalyzed lactonization. Coupling of the lactones with the D-ring is accomplished by formylation and subsequent treatment with bromobutenolide 8 to give GR24 and its dimethyl analogues. Bioassays with Striga hermonthica seeds reveal that the dimethyl analogues are slightly less active than GR24 itself. (C) 2010 Elsevier Ltd. All rights reserved.