作者:Takashi Nakahata、Shohei Fujimura、Shigefumi Kuwahara
DOI:10.1002/chem.200600134
日期:2006.6.2
Pteridic acid A (1) is a spirocyclic octaketide produced by the phytoepiphytic actinomycete Streptomyces hygroscopicus TP-A0451 and possesses potent plant-growth-promoting activity comparable to that of indole-3-acetic acid. The enantioselective total synthesis of this natural product was achieved by employing the Sn(OTf)(2)-mediated Evans aldol reaction and the Fukuyama acetylenic coupling reaction
蕨类酸A(1)是由植物表生放线菌吸水链霉菌TP-A0451产生的螺环环肽,具有与吲哚-3-乙酸相当的有效的植物生长促进活性。通过使用Sn(OTf)(2)介导的Evans aldol反应和Fukuyama炔键偶联反应作为关键的C-C键形成步骤(通过14个步骤序列产生1个键),实现了该天然产物的对映选择性全合成已知的恶唑烷酮衍生物的总收率为22%。MgBr(2)介导的合成1所用的异氰酸酯类螺环中间体的平衡导致螺中心的部分差向异构化,从而产生相应的无原子性差向异构体,该异构体被转化为蝶酸B(11-epi-1),