A concise asymmetric synthesis of (+)-swainsonine (ent-1) is described starting from 2, which was readily prepared from commercially available L-glutamic acid. The method features installation of the indolizidine ring via an intramolecular cyclisation of α-sulfinyl carbanion as a key step. (+)-Swainsonine was obtained in 11.8% overall yield in 10 steps.
Divergent Method to <i>trans</i>-5-Hydroxy-6-alkynyl/alkenyl-2-piperidinones: Syntheses of (−)-Epiquinamide and (+)-Swainsonine
作者:Chang-Mei Si、Zhuo-Ya Mao、Han-Qing Dong、Zhen-Ting Du、Bang-Guo Wei、Guo-Qiang Lin
DOI:10.1021/acs.joc.5b00803
日期:2015.6.5
An efficient diastereoselective approach to access trans-5-hydroxy-6-alkynyl/alkenyl-2-piperidinones has been developed through nucleophilic addition of α-chiral aldimines using alkynyl/alkenyl Grignardreagents. The diastereoselectivity of alkenyl in C-6 position of 2-piperidinone was controlled by α-alkoxy substitution, while the alkynyl was controlled by the coordination of the α-alkoxy substitution