Formation of spiro ketolactones versus alkoxy radical fragmentation-promoted three-atom ring enlarged lactones from cyclic ketones
作者:Alfred Hassner、Tarun K. Pradhan
DOI:10.1016/j.tetlet.2006.05.151
日期:2006.7
ketolactones 4 or of ring enlarged lactones 7 in one-step. Thus, iodination of 5–8-membered 2-allyl-2-carboethoxycycloalkanones 1a–d led, in excellent yields, to spiro ketolactones 4a–d, respectively, as single stereoisomers. On the other hand, iodination of 1a–d under alkoxy radical fragmentation conditions via incipient hemiketals produced the 8-, 9-, 10-, or 11-membered, three-atom ring enlarged, poly-functionalized
来自容易获得的2-烯丙基-2-碳乙氧基环链烷酮1的双重途径一步一步提供了功能化的螺酮内酯4或环扩大的内酯7的新的简便的立体选择性合成。因此,5-8元的2-烯丙基-2-羰基乙氧基环烷酮1a - d的碘化,以优异的产率分别导致了螺酮内酯4a - d的形成,成为单一的立体异构体。另一方面,在烷氧基自由基裂解条件下,通过初期半缩酮对1a - d的碘化反应会生成8元,9元,10元或11元三原子环扩大的多官能内酯7a。– c为两个立体异构体,8为单个异构体。