Total Synthesis of (鈭?-Vindoline and (+)-4-epi-Vindoline Based on a 1,3,4-Oxadiazole Tandem Intramolecular [4 + 2]/[3 + 2] Cycloaddition Cascade Initiated by an Allene Dienophile

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• 作者：Justin E. Sears ; Timothy J. Barker ; Dale L. Boger
• 刊名：Organic Letters
• 出版年：2015
• 出版时间：November 6, 2015
• 年：2015
• 卷：17
• 期：21
• 页码：5460-5463
• 全文大小：369K
• ISSN：1523-7052

文摘

It is reported that an allene dienophile can initiate a tandem intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of 1,3,4-oxadiazoles, that the intermediate cross-conjugated 1,3-dipole (a carbonyl ylide) can participate in an ensuing [3 + 2] dipolar cycloaddition in a remarkably effective manner, and that the reaction can be implemented to provide the core pentacyclic ring system of vindoline. Its discovery improves a previous total synthesis of (鈭?-vindoline and was used in a total synthesis of (+)-4-epi-vindoline and (+)-4-epi-vinblastine that additionally enlists an alternative series of late-stage transformations.