Acid-catalyzed reactions of sarcophytoxide, a marine cembranoid: An apparently enantio-directive reaction, unusual products and stereochemical reconsideration of epoxide-ketone rearrangement
Acid-catalyzed reactions of sarcophytoxide, a marine cembranoid: An apparently enantio-directive reaction, unusual products and stereochemical reconsideration of epoxide-ketone rearrangement
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DOI：
10.1246/bcsj.81.562
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发表时间：
2008-05-15
影响因子：
4
通讯作者：
Kusumi, Takenori
中科院分区：
文献类型：
--
作者：
Nii, Keiji;Tagami, Keiko;Kusumi, Takenori
高氯酸处理石藻氧化物（一种具有环氧化物的海洋西松烷类化合物），引起环氧化物-酮重排，产生酮。当反应时间较长（22小时）时，会形成与短时间（10分钟）反应中获得的酮相反的少量酮。考虑到起始环氧化物具有三个不对称碳，这些令人费解的发现是通过调查其他酮产品的结构来解释的。错误指定的主要酮的立体化学通过对核磁共振谱的广泛分析进行了纠正。正确的立体化学表明环氧化物-酮重排是通过阳离子中间体进行的。
Perchloric acid treatment of sarcophytoxide, a marine cembranoid possessing an epoxide, brought about epoxide-ketone rearrangement affording ketones. When the reaction time was long (22 h), a minor ketone that was antipodal to the ketone obtained in a short-time (10 min) reaction was formed. These puzzling findings, considering that the starting epoxide had three asymmetric carbons, were interpreted by surveying the structures of other ketonic products. The stereochemistry of a major ketone, which had been wrongly assigned, was corrected by extensive analyses of NMR spectra. The correct stereochemistry indicated that the epoxide-ketone rearrangement took a course via a cationic intermediate.