第20709和20710页。在该论文的已发布版本中,2w和2x的反式:顺式比例相反。通过NOE实验以及将旋光度数据与转换后报告的值进行比较,证实了修改后的结果。校正后的表3如下所示。此更正不影响本文的结论。通过1 H NMR分析粗反应混合物确定。孤立的产量。产物的ee通过手性HPLC或GC测定。反式异构体的收率由1计算分离的异构体混合物的1 H NMR分析。以43%的产率和94%的ee获得顺式异构体。获得了作为主要产物的顺式异构体,并且通过对分离的异构体混合物的1 H NMR分析来计算顺式异构体的产率。在提供实验细节的支持信息文件中,2w和2x的绝对配置被错误地绘制为(1 R,2 R)(第S26–S28页)。此处提供了经过更正的文件,该文件描述了(1 S,2 R)配置。可从https://pubs.acs.org/doi/10.1021/jacs.1c03211免费获得支持信息。 实验程序
Oxazaborolidinium Ion-Catalyzed Cyclopropanation of α-Substituted Acroleins: Enantioselective Synthesis of Cyclopropanes Bearing Two Chiral Quaternary Centers
作者:Lizhu Gao、Geum-Sook Hwang、Do Hyun Ryu
DOI:10.1021/ja209270e
日期:2011.12.28
A catalytic synthetic route to highly functionalized chiral cyclopropane derivatives was developed by Michael-initiated cyclopropanation of alpha-substituted acroleins with aryl- and alkyl diazoacetates. In the presence of chiral (S)-oxazaborolidinium cation 1b as a catalyst, the reaction proceeded in high yield (up to 93%) with high to excellent diastereoselectivity (up to 98% de) and enantio-selectivity (up to 95% ee).