Stereoselective Synthesis of Polyhydroxylated Quinolizidines from C-Glycosides by One-Pot Double-Conjugate Addition
作者:Wei Zou、Mahendra Sandbhor、Milan Bhasin
DOI:10.1021/jo062057v
日期:2007.2.1
An effective one-pot synthesis of polyhydroxylated quinolizidines from 1-C-(2‘-oxo-4‘-pentenyl)-5-azido-C-glycofuranosides was developed. Reduction of the 5-azido group using triphenylphosphine followed by base treatment produced quinolizidines in good yield. The base-mediated ring-opening β-elimination produced an acyclic α,β-conjugated ketone as a Michael acceptor, which was followed by an intramolecular
自1-多羟基喹的有效一锅合成Ç - (2'-氧代-4'-戊烯基)-5-叠氮基Ç -glycofuranosides被开发。使用三苯基膦还原5-叠氮基,然后进行碱处理,可得到高产率的喹oli嗪。碱基介导的开环β-消除反应产生了一个无环的α,β-共轭酮作为迈克尔受体,随后加入了分子内的氮共轭物以形成氮杂-C-糖吡喃糖苷中间体。同时,糖苷配基的β,γ-双键在碱性条件下迁移形成另一种α,β-共轭酮。随后通过氮杂糖氮进行的分子内缀合物的添加导致以高度立体选择性的方式形成喹喔啉类。产生氮杂糖的第一偶联物添加的立体选择性受单糖底物的立体化学的影响,而第二偶联物添加中的立体选择性很可能完全由氮杂糖的空间排斥作用所决定。