Highly Stereoselective Formal [3 + 3] Cycloaddition of Enals and Azomethine Imines Catalyzed by <i>N</i>-Heterocyclic Carbenes
作者:Audrey Chan、Karl A. Scheidt
DOI:10.1021/ja0709167
日期:2007.5.1
are effective catalysts for generating homoenolate species from α,β-unsaturated aldehydes. The nucleophilic intermediate adds to azomethine imines, and the resulting activated carbonyl unit undergoes an intramolecular acylation event. This formal [3 + 3] cycloaddition between α,β-unsaturated aldehydes and azomethine imines catalyzed by NHC has been developed to give substituted pyridazinones in good to
衍生自 N-甲基苯并咪唑鎓盐的 N-杂环卡宾是从 α,β-不饱和醛生成均烯醇化物的有效催化剂。亲核中间体加成到偶氮甲碱亚胺上,所得活性羰基单元经历分子内酰化事件。这种由 NHC 催化的 α,β-不饱和醛和偶氮甲碱亚胺之间的正式 [3 + 3] 环加成反应可以得到具有高非对映选择性 (>20:1) 的取代哒嗪酮,收率良好至极好。NHC 催化的反应可容纳芳香族和烷基 α,β-不饱和醛和各种芳香族偶氮甲亚胺。在加入醇或胺后,哒嗪酮可以进行选择性六元环开环,得到酯和酰胺。