Base-Selective Five- versus Six-Membered Ring Annulation in Palladium-Catalyzed C-C Coupling Cascade Reactions: New Access to Electron-Poor Polycyclic Aromatic Dicarboximides
作者:Sabine Seifert、David Schmidt、Kazutaka Shoyama、Frank Würthner
DOI:10.1002/anie.201702889
日期:2017.6.19
Suzuki–Miyaura cross‐coupling and direct C−H arylation afforded a series of new five‐ and six‐membered ring annulated electron‐poor polycyclic aromatic hydrocarbons. Cesium carbonate (Cs2CO3) as auxiliary base in these C−C coupling cascade reactions led exclusively to six‐membered ring annulation, while the use of organic base diazabicycloundecene (DBU) afforded the corresponding five‐membered ring
Suzuki-Miyaura交叉偶联和直接CHH芳基化反应使钯对二溴邻苯二甲酰亚胺的碱选择性环化成不同的芳基硼酸酯,提供了一系列新的五元和六元环化的电子贫化多环芳烃。碳酸铯(Cs 2 CO 3)作为这些C-C偶联级联反应的辅助碱仅导致六元环环化,而有机碱二氮杂双环十一碳烯(DBU)的使用提供了相应的五元环环化产物。这种依赖于碱基的环空选择模式归因于所应用的碱基所指导的不同机械途径。通过对五元和六元环空环化产品的单晶X射线分析揭示了选择性环空。通过紫外/可见吸收,荧光光谱和循环伏安法对新型多环芳族二羧酰亚胺的光学和氧化还原特性进行了表征。