18O Assisted Analysis of a 纬,未-Epoxyketone Cyclization: Synthesis of the C16鈭扖28 Fragment of Ammocidin D

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• 作者：Stephen T. Chau ; Yoichi Hayakawa ; Gary A. Sulikowski
• 刊名：Organic Letters
• 出版年：2011
• 出版时间：February 18, 2011
• 年：2011
• 卷：13
• 期：4
• 页码：756-759
• 全文大小：765K
• 年卷期：v.13,no.4(February 18, 2011)
• ISSN：1523-7052

文摘

The C16鈭扖28 fragment common to the cytotoxic macrolide ammocidin D has been prepared by a stereospecific 5-exo closure of a 纬,未-epoxyketone followed by a rearrangement to a pyran acetal. The reaction pathway was traced by ¹⁸O labeling of the keto carbonyl and observation of ¹⁸O induced ¹³C shifts in the pyran acetal product. NMR data of the synthetic C16鈭扖28 fragment compared favorably to the natural product providing support of the assigned stereochemistry.