Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of   the Excess Base

doi:10.1021/acscatal.5b02089

CORC > 北京大学 > 化学与分子工程学院

	Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base
	Xu, Liping ; Chung, Lung Wa ; Wu, Yun-Dong
刊名	ACS CATALYSIS
	2016
关键词	nickel N-heterocyclic carbene hydrogenolysis C-O activation biomass H-2 activation C-O BONDS CROSS-COUPLING REACTIONS TRANSITION-METAL CENTERS CARBON-CARBON BONDS OXIDATIVE ADDITION DENSITY FUNCTIONALS REDUCTIVE CLEAVAGE CHEMICAL-REACTIONS GRIGNARD-REAGENTS NICKEL-CATALYSTS
DOI	10.1021/acscatal.5b02089
英文摘要	The transformation of aromatic carbon oxygen (C-Ar-O) bonds in lignin to useful chemical building blocks has great potential in biomass conversion. A Ni-NHC (N-heterocyclic carbene) catalyzed selective hydrogenolysis of aryl ethers has recently been developed by Hartwig and co-worker, but the reaction mechanism, including the role of different additives found to accelerate the reaction and the origin of the selectivity, remains unclear. DFT calculations of several possible pathways for this useful and important transformation suggest a new mechanistic pathway which involves coordination of the excess base ((BuO-)-Bu-t) to facilitate the rate-determining C-O activation step, dissociation of the ArO- ligand, H-2 activation through a Ni-(OBu)-Bu-t bond to give (HOBu)-Bu-t, and finally reductive elimination to afford the arene product. Another new ion-pair (SNAr-like) pathway for the base-assisted C-O bond activation could compete with the above base-assisted oxidative addition pathway for some diaryl ethers. The regioselective cleavage of different ethers and the effects of the Lewis acid were also examined and compared. The results demonstrate that bulkiness and strong donating ability of the NHC ligand and the presence of excess base are the keys to a Ni(O)/Ni(II) catalytic cycle.; National Natural Science Foundation of China [21133002, 21473086]; Shenzhen Peacock Program [KQTD201103, KQTD20150717103157174]; South University of Science and Technology of China; SCI(E); EI; ARTICLE; oscarchung@sustc.edu.cn; 1; 483-493; 6
语种	中文
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/437847]
专题	化学与分子工程学院
推荐引用方式 GB/T 7714	Xu, Liping,Chung, Lung Wa,Wu, Yun-Dong. Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base[J]. ACS CATALYSIS,2016.
APA	Xu, Liping,Chung, Lung Wa,&Wu, Yun-Dong.(2016).Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base.ACS CATALYSIS.
MLA	Xu, Liping,et al."Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base".ACS CATALYSIS (2016).