Stereoselective Approach to Hydroxyindolizidines: Protection/Deprotection of the Nitrone Functionality via Cycloaddition/Retrocycloaddition
作者:Franca M. Cordero、Martina Gensini、Andrea Goti、Alberto Brandi
DOI:10.1021/ol006125q
日期:2000.8.1
The enantiomerically pure indolizidine (-)-21 has been synthesized starting from L-malic acid. The key intermediate 20 has been assembled through an intramolecular 1,3-dipolar cycloaddition of a nitrone generated in situ by retrocycloaddition from isoxazolidine 17 or 18. The configuration of the new three stereocenters was set up with complete control in the cycloaddition step. The presented synthetic
从L-苹果酸开始合成对映体纯的吲哚唑烷(-)-21。关键中间体20已经通过由异恶唑烷17或18的反式环加成而在现场产生的硝酮的分子内1,3-偶极环加成而组装。在环加成步骤中完全控制地建立了新的三个立体中心的构型。提出的合成途径为具有[1,8a]-顺式构型的吲哚并咪唑提供了一种通用且高度选择性的方法。