A Divergent and Stereoselective Approach for the Syntheses of Some Polyhydroxylated Indolizidine and Pyrrolizidine Iminosugars
作者:Anugula Rajender、Jalagam Prasada Rao、Batchu Venkateswara Rao
DOI:10.1002/ejoc.201201342
日期:2013.3
A common, divergent, and efficient approach to the syntheses of (+)-steviamine (9), (–)-1-deoxy-8a-epi-castanospermine (10), (+)-trihydroxyindolizidine (11), (+)-3,7a-di-epi-hyacinthacine A1 (12), and (–)-2-epi-lentiginosine (4) was achieved by starting from D-ribose-derived intermediate 13. The key steps involved in these syntheses are a highly diasteroselective Grignard addition to a ribosylimine
(+)-steviamine (9), (–)-1-deoxy-8a-epi-castanospermine (10), (+)-trihydroxyindolizidine (11), (+) -3,7a-di-epi-hyacinthacine A1 (12) 和 (-)-2-epi-lentiginosine (4) 是从 D-核糖衍生的中间体 13 开始获得的。这些合成中涉及的关键步骤是核糖亚胺的高度非对映选择性格氏加成、一锅立体选择性分子内还原胺化、甲硅烷基醚的选择性脱保护和闭环复分解 (RCM) 反应。