β-内酯亲电体会与多种基于氮的亲核体发生区域选择性加成-消除(AE)或S N 2开环。伯胺和仲胺可促进AE开环,从而提供功能上与酰胺醇醛加合物相同的产品。叠氮化物和磺酰胺阴离子亲核试剂使S N 2内酯开环传递N保护的β-氨基酸衍生物。这些依赖亲核试剂的开环途径,再加上通过酰基卤-醛环缩合反应获得的富含大量庚酮的β-内酯的便捷途径,构成了不对称有机合成的通用方法。还描述了该反应技术在基于从AAC开环序列中出现的旋光性β-叠氮酸的β肽合成新方法中的应用。
Practical Enantioselective Synthesis of β-Lactones Catalyzed by Aluminum Bissulfonamide Complexes
作者:Thomas Kull、René Peters
DOI:10.1002/adsc.200700084
日期:2007.7.2
practical aluminum-bissulfonamide complex catalyzed enantioselective formation of β-lactones by [2+2] cycloaddition of ketene (generated in situ from acetyl bromide by dehydrobromination) with various α-unbranched and -branched aliphatic aldehydes is presented. The methodology offers the advantage of operational simplicity not only as the ligand synthesis requires just a single sulfonylation step from commercially