Preparation of 5-bromotetronates [4-alkoxy-5-bromo-2(5H)-furanones] and a new concept for the synthesis of aflatoxins and related structure types. Tributyltin hydride versus palladium-promoted intramolecular hydroarylation.
作者:H. Martin、R. Hoffmann、Boris Schmidt、Stefan Wolff
DOI:10.1016/s0040-4020(01)85124-3
日期:1989.1
4-alkoxy-5-bromo-2(5H)-furanones (5-bromotetronates) (10a-e) gave precyclic aflatoxin M1 A-C building blocks (7, 14, 17c). Two cyclization modes for obtaining the ABC-moiety were investigated and compared. Whereas the Bu3SnH-induced reaction worked well for simple model compounds, it failed for the more functionalized compounds. The palladium-mediated procedure allowed the synthesis of potential aflatoxin
适当官能化的邻碘苯酚(例如6)与4-烷氧基-5-溴-2(5H)-呋喃酮(5-溴代酸酯)(10a-e)的偶联产生了环前黄曲霉毒素M 1 AC结构单元(7,7,14 , 17c)。研究并比较了两种获得ABC部分的环化模式。尽管Bu 3 SnH诱导的反应对于简单的模型化合物效果很好,但对于功能化程度更高的化合物却不起作用。钯介导的程序可以合成潜在的黄曲霉毒素M 1前体,例如18c。描述了一种用于获得O-烷基化的四磺酸盐(9a-g)的改进方法。将四价酸盐转化为5-溴四价酸盐(10a-e,h)在受控的自由基条件下。例如,将narthogenin前体10a制备为排除不期望的异构体11,产率为62%。最后,通过两种环化方法以良好至优异的产率获得了其他苯并环化的杂二奎烷,例如脱氧埃塞林啉前体24。