Synthesis of Optically Active Indolizidines: (-)-8a-epi-Dendroprimine and (-)-7,8-Dehydro-5,6-dimethylindolizidine
作者:Michel Diederich、Udo Nubbemeyer
DOI:10.1055/s-1999-3396
日期:1999.2
Indolizidinones can be employed as key intermediates in efficient asymmetric synthesis of naturally occurring indolizidine alkaloid analogues. The 5,7-dimethylindolizidine (-)-8a-epi-dendroprimine was formed by a diastereoselective methylation-reduction sequence of the lactam function. The (-)-5,6-dimethylindolizidine was generated via the same key step including an additional quasi 1,2-methyl shift: an intramolecular enamine alkylation is followed by regioselective reductive cyclopropane ring opening.
吲哚利定酮可用作天然吲哚利定生物碱类似物的高效不对称合成中的关键中间体。5,7-二甲基吲哚利定(-)-8a-表-登普利明通过内酰胺官能团的非对映选择性甲基化-还原序列形成。(-)-5,6-二甲基吲哚利定通过包括额外的准1,2-甲基转移的相同关键步骤生成:分子内腙烷基化后是位点选择性还原环丙烷环开环。