Evidence for a stepwise mechanism in formal hetero-Diels-Alder reactions of N-arylimines
作者:Frank Linkert、Sabine Laschat、Sirpa Kotila、Thomas Fox
DOI:10.1016/0040-4020(95)00947-7
日期:1996.1
17d,f with terminal alkene or alkyne moieties could not be cyclized under these conditions, imine 17b with a C-3 tether gave three diastereomeric pyrrolo-[1′,2′:1,2]azepino[3,4-b]quinolines 18a-c and imine 17c gave two diastereomeric 7,7-diphenyl-indolizino-[3,4-b]quinolines 19a,b. High cis/trans-ratios were observed in both cases. Imine 17e bearing an internal alkyne underwent a cyclization/dehydrogenation
为了研究路易斯酸催化ω-不饱和N-芳基丙氨酸环化的机理,合成了各种脯氨酸衍生的N-芳基丙氨酸17a-f并用路易斯酸处理。在这些条件下,带有C-2系链的亚胺17a和带有末端烯烃或炔烃部分的亚胺17d,f不能环化,而带有C-3系链的亚胺17b给出了三个非对映体吡咯并-[1',2':1, 2] azepino [3,4-b]喹啉18a-c和亚胺17c得到两个非对映体7,7-二苯基-吲哚并ino- [3,4-b]喹啉19a,b。在两种情况下均观察到高的顺式/反式比率。亚明17e带有内部炔烃的化合物进行环化/脱氢,得到吲哚并[3,4-b]喹啉21。从这些结果得出了逐步的机制。的配置19A是由一个X射线晶体结构分析确定。