rearrangement was directly engaged in aldol cyclization while baconipyrone C resulted from simple ketonization of the enol(ate). These experiments provide the first unambiguous demonstration that the baconipyrones are plausible isolation artifacts and suggest they are most likely derived from siphonarins rather than an "acyclic" precursor. Caloundrin B was not detected among the products from any of the isomerization
通过检查 S. zelandica 十
丙酸酯 siphonarin B、caloundrin B、baconipyrone A 和 baconipyrone C 的假定共同前体的特性,测试了 siphonariid polypropionates 源自对无环
生物合成前体的非酶促过程的假设,即(4S,5S, 6S,8RS,10S,11S,12R,14R)-14-(6-ethyl-3,5-dimethyl-4-oxo-4H-pyran-2-yl)-5,11-dihydroxy-4,6,8 ,10,12-pentamethylpentadecane-3,7,9,13-tetraone。使用基于
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丙酸酯合成策略,以有效且完全对映选择性的方式实现了此类前体的首次合成。这种推定的前体是环链互变异构体和
酮-
烯醇互变异构体的复杂混合物,在动力学上是稳定的,并且异构化为热力学更稳定的虹吸素 B。在
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