Synthesis of Optically Pure 2-Azetidinones Having <i>N</i>-Dehydroamino Acid Side-Chains
作者:Benito Alcaide、Concepción Polanco、Miguel A. Sierra
DOI:10.1055/s-1998-1667
日期:1998.4
An efficient, three step synthesis of optically pure N-vinyl-2-azetidinones 1 starting from α- or β-amino ester imines has been developed. Staudinger reaction between amino ester derived imines and ketene precursors gave 2-azetidinones 2. Enolate formation on the amino ester moiety of the optically pure 2-azetidinones 2, selenylation and, finally, MCPBA treatment afforded N-vinyl-2-azetidinones 1 in good to excellent yields, with total retention of the stereochemistry of the starting material. Compounds 2 bear the functionality needed to place a carboxy group contiguous to the lactam nitrogen, a structural feature common to all the active β-lactam antibiotics.
从 δ- 或 δ²- 氨基酯亚胺开始,开发出了一种高效的三步合成光学纯 N-乙烯基-2-氮杂环丁酮 1 的方法。由氨基酯衍生的亚胺和烯酮前体发生施陶丁格反应,得到 2-氮杂环丁酮 2。在光学纯度较高的 2-氮杂环丁酮 2 的氨基酯分子上形成烯酸盐,然后进行硒化,最后经 MCPBA 处理,得到 N-乙烯基-2-氮杂环丁酮 1,收率从良好到极佳,并完全保留了起始原料的立体化学结构。化合物 2 具有将羧基与内酰胺氮相连所需的官能度,这是所有活性 δ-内酰胺类抗生素共有的结构特征。