Concise Enantioselective Total Syntheses of (+)-Homochelidonine, (+)-Chelamidine, (+)-Chelidonine, (+)-Chelamine and (+)-Norchelidonine by a PdII-Catalyzed Ring-Opening Strategy
作者:Matthew J. Fleming、Helen A. McManus、Alena Rudolph、Walter H. Chan、Jérémy Ruiz、Chris Dockendorff、Mark Lautens
DOI:10.1002/chem.200701775
日期:2008.2.27
II-catalyzed asymmetric ring-opening reaction of a meso-azabicyclic alkene with an aryl boronic acid as the key step. By screening a variety of functionalized ortho-substituted aryl boronic acids, chiral ligands and reaction conditions we were able to prepare the requisite cis-1-amino-2-aryldihydronaphthalenes in high yield and in up to 90 % ee. Early attempts to complete the synthesis of (+)-homochelidonine
描述了B / C六氢苯并[c]菲啶生物碱(+)-高纯菜碱碱,(+)-氯idine烷,(+)-螯合碱,(+)-螯合胺和(+)-去甲螯合碱的新的对映选择性合成。我们针对此类天然产物的快速且趋同的途径涉及开发和应用Pd II催化的中氮杂双环烯烃与芳基硼酸的不对称开环反应,这是关键步骤。通过筛选各种官能化的邻位取代的芳基硼酸,手性配体和反应条件,我们能够以高收率和高达90%ee的条件制备必需的cis-1-氨基-2-芳基二氢萘。完整描述了使用N-Boc氮杂双环烯烃完成(+)-单烯胆碱合成的早期尝试。成功的途径需要保护基团的改变,然后形成B环,然后通过使用氢化物源的区域选择性环氧化物开环来立体选择性地安装C-11顺式羟基。相同的环氧中间体与水的开环最终导致(+)-氯chel啶的合成。然后,使用相同的策略来合成其他结构相似的B / C六氢苯并[c]菲啶生物碱,(+)-鸟苷,(+)-胺和(+)-去甲鸟氨酸。