Pd-PEPPSI Complexes Bearing Bulky [(1,2-Di-(tert-butyl)acenaphthyl] (DtBu-An) on N-Heterocarbene Backbones: Highly Efficient for Suzuki–Miyaura Cross-Coupling under Aerobic Conditions

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• 作者：Xiao-Bing Lan ; Fu-Min Chen ; Bei-Bei Ma ; Dong-Sheng Shen ; Feng-Shou Liu
• 刊名：Organometallics
• 出版年：2016
• 出版时间：November 28, 2016
• 年：2016
• 卷：35
• 期：22
• 页码：3852-3860
• 全文大小：557K
• ISSN：1520-6041

文摘

With the goal of achieving highly efficient palladium-catalyzed cross-coupling reactions under mild reaction conditions, the Pd-PEPPSI complexes C1 and C2 bearing 1,2-di(tert-butyl)acenaphthyl (DtBu-An) backbones were synthesized and characterized, and their use in Suzuki–Miyaura cross-coupling was investigated. The effects of catalyst structure and reaction conditions on the cross-coupling efficiency were evaluated in detail. The significant differences in catalytic activity compared with classical PEPPSI-IPr and PEPPSI-IPr^An precatalysts are discussed, where the axial sterics on the backbone play an important role. At low palladium loadings of 0.05–0.1 mol % and upon the addition of the relatively weak base K₃PO₄, the palladium complex C1 was found to be highly efficient for the coupling of (hetero)aryl chlorides with arylboronic acids under aerobic conditions, affording the corresponding biaryls in excellent yields.