N-Heterocyclic Carbene and Brønsted Acid Cooperative Catalysis: Asymmetric Synthesis of <i>trans</i>-γ-Lactams
作者:Xiaodan Zhao、Daniel A. DiRocco、Tomislav Rovis
DOI:10.1021/ja205714g
日期:2011.8.17
An efficient enantioselective approach to form trans-γ-lactams in up to 99% yield, 93% ee, and >20/1 dr using unactivated imines has been developed. The cyclohexyl-substituted azolium and the weak base sodium o-chlorobenzoate are most suitable for this transformation. Notably, the process involves cooperativecatalysis by an N-heterocycliccarbene and a Brønsted acid.
已经开发出一种使用未活化亚胺以高达 99% 的产率、93% 的 ee 和 >20/1 dr 的高效对映选择性方法形成反式-γ-内酰胺。环己基取代的唑鎓和弱碱邻氯苯甲酸钠最适合这种转化。值得注意的是,该过程涉及 N-杂环卡宾和布朗斯台德酸的协同催化。