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ow在路上

铜虫 (正式写手)

[求助] 求翻译一篇文献中的一部分

It is known that the reveromycin A ( 1)-type 6,6-spiroketal core I can undergo acid-catalyzed isomerization to afford the spiroisomer II as the result of an unfavorable steric interaction involving the axial C19 side chain in I that is alleviated in II , albeit at the cost of an anomeric effect (Figure 1). Thus, the energy difference between the 6,6-spiroketals I and II is small. In addition, when the C18 alcohol is free, acid-induced isomerization provides the more stable reveromycin B (2) 5,6-spiroketal coreIII exclusively. This energy profile has been observed in the reported thermodynamic approaches (i.e., cyclization of a “dihydroxy-ketone” precursor) to the 6,6-spiroketal of 1, which providedmixtures of spiroisomers,and degradative and synthetic
studies  have demonstrated the strong preference for the reveromycin B-type 5,6-spiroketal III.
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13599388598

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【答案】应助回帖


爱与雨下(金币+1): 2011-12-04 09:59:30
ow在路上(金币+5, 翻译EPI+1): 谢谢 2011-12-07 11:57:34
总所周知reveromycin A ( 1)-type 6,6-spiroketal的I型核心能进行酸催化的异构化作用,使II型螺旋异构体得到不好的空间相互作用结果,包括绕轴的C19侧链,尽管这消耗了端基异构效应,在I型比II型结果稍好。因此,I型和II型的 6,6-spiroketals之间的能量差异不大。另外当C18酒精释放时,酸诱导的异构体特异的提供了更稳定的reveromycin B (2) 5,6-spiroketal的III型核心。

在已报道的对6,6-spiroketal of 1的热力方法中观察到了能线图,这为螺旋异构体的混合物reveromycin B-type 5,6-spiroketal降解和合成的研究提供了强有力的证明。
2楼2011-12-03 13:58:42
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