Efficient total syntheses of (1R, 2R, 3R, 9R, 9aR)-1,2,3,9-tetrahydroxyquinolizidine and its enantiomer
作者:Gloria Rassu、Giovanni Casiraghi、Luigi Pinna、Pietro Spanu、Fausta Ulgheri、Mara Cornia、Franca Zanardi
DOI:10.1016/s0040-4020(01)81832-9
日期:1993.7
Highly diastereoselective homologation of imine 5 (or ent-5) using 2-(trimethylsiloxy)furan provided the nine-carbon butenolide 6 (or ent-6) which was elaborated into the quinolizidine 10 (or ent-10) via a clean sequence involving, as key operations, DBU-promoted γ-lactone to δ-lactam ring expansion (e.g. 7 to 8) and cyclodehydration of a fully-deprotected hydroxypiperidine employing Ph3P, CCl4, Et3N
分别从D-阿拉伯糖和L-阿拉伯糖实现了两个对映体四羟基喹oli嗪10和ent- 10的简明合成。使用2-(三甲基甲硅烷氧基)呋喃对亚胺5(或ent- 5)进行高度非对映选择性同源化,提供了九碳丁烯内酯6(或ent- 6),该过程经清洁顺序合成为喹oli嗪10(或ent- 10)。 ,作为关键操作,DBU促进了γ-内酯至δ-内酰胺环的扩展(例如7至8),以及使用Ph 3 P,CCl 4将完全脱保护的羟基哌啶进行了环脱水,Et 3 N(例如9到10)。该过程包括5个步骤或5个步骤的5个步骤,并以36-37%的总收率提供标题喹喔嗪10或对映体10。