Silyl Triflate-Mediated Ring-Closure and Rearrangement in the Synthesis of Potential Bisfuran-Containing Intermediates of Aflatoxin Biosynthesis
作者:Todd L. Graybill、Eduard G. Casillas、Kollol Pal、Craig A. Townsend
DOI:10.1021/ja990591x
日期:1999.9.1
strategy is described involving two silyl triflate-mediated cyclization and rearrangement processes that have enabled both furofuran oxidation states to be readily achieved and undesired but thermodynamically favorable side reactions to be avoided in the preparation of these ring systems. In the first an o-methoxymethyl phenylacetaldehyde is cyclized directly to the five-membered, differentially protected
强效真菌毒素黄曲霉毒素 B1 的生物合成途径异常长且复杂,从蒽醌到氧杂蒽酮再到带有稠合四氢和双二氢呋喃环的香豆素核类型。描述了一种合成策略,涉及两个甲硅烷基三氟甲磺酸酯介导的环化和重排过程,这使得在这些环系统的制备中能够容易地实现两种呋喃氧化态并避免不希望的但热力学有利的副反应。在第一个中,邻甲氧基甲基苯乙醛直接环化为五元不同保护的半缩醛,而在第二个中,该基团经适当取代后可重排为 4-三烷基甲硅烷氧基-2,5-甲氧基-1,3-苯二氧六环。后者掩蔽二醛对强碱、弱酸、和氧化剂,以允许构建所有需要的芳环系统。使用这些方法,全合成 (±)-versicolorin B、(±)-versicolorin A、其半...