Stereoselective synthesis of polyfunctional di- and trisubstituted cyclopentane derivatives using a new palladium catalyzed cyclization.
作者:Heinz Stadtmüller、Charles E. Tucker、Andrea Vaupel、Paul Knochel
DOI:10.1016/s0040-4039(00)61508-3
日期:1993.12
undergo a radical ring closure to give cyclopentylmethylzinc iodides when treated with Et2Zn in the presence of PdCl2(dppf) (2 mol %). In the case of 4-substituted 5-hexenyl iodides trans-cyclopentanes are obtained (> 99 : 1) whereas 1-substituted-5-hexenyl iodides provide cis-cyclopentanes (ca. 80 : 20). The presence of a substituent at both positions considerably improves the cis stereoselectivity up to
当在PdCl 2(dppf)(2 mol%)存在下用Et 2 Zn处理时,各种官能化的5-己烯基碘化物会发生自由基闭环反应,得到环戊基甲基碘化锌。在4-取代的5-己烯基碘的情况下,获得反式-环戊烷(> 99:1),而1-取代的5-己烯基碘化物提供顺式-环戊烷(约80:20)。两个位置都有取代基可显着提高顺式立体选择性,最高可达95:5。