Ir-Catalyzed Cascade C–H Fusion of Aldoxime Ethers and Heteroarenes: Scope and Mechanisms
作者:Zhiqian Yu、Yan Zhang、Junbin Tang、Luoqiang Zhang、Qianhui Liu、Qian Li、Ge Gao、Jingsong You
DOI:10.1021/acscatal.9b04274
日期:2020.1.3
of phenanthridine derivatives is achieved by an iridium-catalyzed direct fusion of oxime ethers and heteroarenes, which is a successful example of a cascade C–H/C–H cross-coupling/cyclization strategy for polycyclic heteroaromatic synthesis. By subtle tuning of the reaction conditions, both benzo- and simple five-membered heteroarenes are suitable substrates under similar but different conditions. The
通过铱催化肟醚和杂芳烃的直接融合,可实现菲啶衍生物的简明合成,这是多环杂芳族合成的级联C–H / C–H交叉偶联/环化策略的成功实例。通过微调反应条件,在相似但不同的条件下,苯并五元杂芳基和简单的五元杂芳基都是合适的底物。关键是正确选择银盐。详细的机理研究表明,第一步C–H / C–H交叉偶联步骤涉及[Ir II ] – [Ir IV ]催化循环,需要Ag 2 O作为氧化剂。对于第二个环化步骤,自由基过程控制了苯并杂芳烃和Ag 2的反应O是必需的;然而,在涉及[Ir I ]-[Ir III ]催化循环的简单五元杂芳烃的反应中,C–H环化作用是必要的,而AgTFA是必需的。