A divergent approach for asymmetric syntheses of (+)-spicigerine, (+)-cassine and their 3-epimers
作者:Pan Han、Chang-Mei Si、Zhuo-Ya Mao、Hai-Tong Li、Bang-Guo Wei、Zhen-Ting Du
DOI:10.1016/j.tet.2015.12.057
日期:2016.2
An efficient approach for asymmetric synthesis of (+)-spicigerine, (+)-cassine and their 3-epimers has been developed through the intramolecular diastereoselective tandem addition/cyclisation process of alpha-chiral aldimine 9 with methylmagnesium bromide and the asymmetric addition of nucleophilic reagents to aminal 14. Moreover, the first asymmetric synthesis of (+)-spicigerine has been achieved in this manuscript. In this synthetic strategy, the asymmetric syntheses of (+)-spicigerine and (+)-cassine was achieved in a 14% overall yield and nine steps and an 18% overall yield and seven steps from cheap a chiral aldimine 9, respectively. (C) 2015 Elsevier Ltd. All rights reserved.