期刊
CHEMISTRY-AN ASIAN JOURNAL
卷 13, 期 4, 页码 440-448出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/asia.201701734
关键词
amides; atom economy; carbenes; reaction mechanisms; ruthenium
资金
- National Natural Science Foundation of China [21502062]
- Hubei Provincial Department of Education [Q20102606]
- Xiangyang Science and Technology Bureau [2010GG1B33]
- open project of electromechanical-automobile discipline of Hubei province [XKQ2017027]
- Tomsk Polytechnic University Competitiveness Enhancement Program [VIU-316/2017]
The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, insitu generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active insitu catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at =-7.8ppm in the (HNMR)-H-1 spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the insitu generated catalyst system.
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