期刊
CATALYSIS SCIENCE & TECHNOLOGY
卷 12, 期 21, 页码 6581-6589出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/d2cy01136k
关键词
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资金
- Rutgers University
- NIH [R35GM133326]
- NSF [CAREER CHE-1650766]
- NSF-MRI grant [CHE-1229030]
- Rutgers University - Newark Chancellor's Research Office
- China Scholarship Council [201606240022]
- Narodowe Centrum Nauki [2019/35/D/ST4/00806]
- Wroclaw Center for Networking and Supercomputing [WCSS159]
We describe the development of ImPy complexes of [(NHC)Pd(cinnamyl)Cl] as versatile precatalysts for cross-coupling reactions. These precatalysts exhibit fast activation and high reactivity, making them useful in organic synthesis and catalysis. A scalable synthesis of C5-substituted imidazo[1,5-a]pyridin-3-ylidene ligands through Ni-catalyzed Kumada cross-coupling is also disclosed.
We describe the development of [(NHC)Pd(cinnamyl)Cl] complexes of ImPy (ImPy = imidazo[1,5-a]pyridin-3-ylidene) as a versatile class of precatalysts for cross-coupling reactions. These precatalysts feature fast activation to monoligated Pd(0) with 1 : 1 Pd to ligand ratio in a rigid imidazo[1,5-a]pyridin-3-ylidene template. Steric matching of the C5-substituent and N2-wingtip in the catalytic pocket of the catalyst framework led to the discovery of ImPyMesDipp as a highly reactive imidazo[1,5-a]pyridin-3-ylidene ligand for Pd-catalyzed cross-coupling of nitroarenes by challenging C-NO2 activation. Kinetic studies demonstrate fast activation and high reactivity of this class of well-defined ImPy-Pd catalysts. Structural studies provide full characteristics of this new class of imidazo[1,5-a]pyridin-3-ylidene ligands. Computational studies establish electronic properties of sterically-restricted imidazo[1,5-a]pyridin-3-ylidene ligands. Finally, a scalable synthesis of C5-substituted imidazo[1,5-a]pyridin-3-ylidene ligands through Ni-catalyzed Kumada cross-coupling is disclosed. The method obviates chromatographic purification at any of the steps, resulting in a facile and modular access to ImPy ligands. We anticipate that well-defined [Pd-ImPy] complexes will find broad utility in organic synthesis and catalysis for activation of unreactive bonds.
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