Synthesis of Pterocarpans by Means of a “Disfavored” 5-endo-trig Radical Cyclization Reaction
作者:Kalpathy Chidambareswaran Santhosh、Ariamala Gopalsamy、Kalputtu Kuppuswamy Balasubramanian
DOI:10.1002/1099-0690(200109)2001:18<3461::aid-ejoc3461>3.0.co;2-9
日期:2001.9
A successful synthesis of pterocarpans 1, based on a "disfavored" 5-endo-trig radical cyclization reaction, has been accomplished. The radical precursor 4-(2'-bromoaryloxy)-2H-chromene 8 was synthesized in six steps, starting from aryl propynyl ether 2. On treatment with tributyltin hydride in refluxing benzene, aryl enol ether 8 underwent radical cyclization to furnish the pterocarpan 1. A deuterium
基于“不受欢迎”的 5-endo-trig 自由基环化反应,成功合成了 pterocarpans 1。自由基前体 4-(2'-溴芳氧基)-2H-色烯 8 从芳基丙炔醚 2 开始,分六步合成。 在回流苯中用氢化三丁基锡处理后,芳基烯醇醚 8 发生自由基环化反应得到紫檀1 . 进行了氘标记研究以证明 5-endo-trig 自由基环化的发生。该方法进一步扩展到合成一类迄今为止未知的 pterocarpans 13。还描述了一种通过 Mitsunobu 反应合成溴醇芳基醚的新型立体选择性路线。