Diastereoselective Synthesis of Nonracemic 2-Alkyl-5-Hydroxypiperidines with (2R,5S)-Configuration via a Tandem Wittig [2+3] Cycloaddition Reaction. Synthesis of epi-Pseudoconhydrine and Its Homologs
作者:Claus Herdeis、Thomas Schiffer
DOI:10.1055/s-1997-1366
日期:1997.12
A diastereoselective synthesis of cis-2-alkyl-5-hydroxypiperidines is presented, starting from enantiopure azidolactone 1. The key step of the reaction sequence is the tandem Wittig [2+3] cycloaddition reaction of lactol 2 to give triazolines 5a,b which are in equilibrium with the diazoamines 6a,b. Thermolysis of the mixture of 5 and 6 provides enantiopure 7, which is O-protected, diastereoselectively hydrogenated, and N-protected to 9. Further transformation of 9 yields epi-pseudoconhydrine (14) and its homologs.
本文介绍了一种中心选择性合成cis-2-烷基-5-羟基哌啶的方法,以手性纯的叠氮内酯1为起始材料。反应序列的关键步骤是内酯2与Wittig [2+3]环加成反应的串联,生成与二氮胺6a,b平衡的三唑啉5a,b。对混合物5和6进行热分解可得到手性纯的7,随后对其进行O保护、中心选择性加氢和N保护,得到9。对9的进一步转化生成epi-拟复水堿(14)及其同系物。