Synthesis of spirocyclopropyl γ-lactams by tandem intramolecular azetidine ring-opening/closing cascade reaction: synthetic and mechanistic aspects
作者:Pierre-Antoine Nocquet、Damien Hazelard、Philippe Compain
DOI:10.1016/j.tet.2012.03.111
日期:2012.6
intramolecular azetidine ring-opening/closing cascade reaction affording spirocyclopropyl γ-lactams from azetidines in high regio- and stereoselectivity is reported. The key step of the process is a SN2-type ring-opening of TMSOTf-activated azetidine rings by silyl ketene acetals generated by treatment with TMSOTf and TEA. This study is a very rare example of nucleophilic ring-opening of azetidines that
报道了新颖的分子内氮杂环丁烷开环/闭合级联反应的范围和局限性,其从氮杂环丁烷以高区域和立体选择性提供螺环丙基γ-内酰胺。该方法的关键步骤是通过用TMSOTf和TEA处理产生的甲硅烷基烯酮缩醛使TMSOTf活化的氮杂环丁烷环S N 2型开环。这项研究是氮杂环丁烷亲核开环的非常罕见的例子,它不需要通过N-烷基化或使用N形成季铵盐-吸电子基团。该方法在2-氮杂环丁酮系统中的应用导致反应活性的完全改变,并通过空前的涉及酯受体和亚氨酸甲硅烷基酯的Mukaiyama aldol-like反应提供6-氮杂双环[3.2.0]庚烷衍生物。