期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 139, 期 25, 页码 8514-8521出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.7b01801
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资金
- National Science Foundation of the USA [CHE-1361104]
- National Science Foundation under CCI Center for Selective C-H Functionalization [CHE-1205646]
- Chinese Thousand Youth Talents Plan
- National Science Foundation [OCI-1053575]
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1361104] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1205646] Funding Source: National Science Foundation
The origin of the unique effectiveness of six-membered chelates on the beta-methylene C(sp3)-H activation reactions by Pd(II) catalyst was explained with density functional theory. The Pd(II) catalysts that involve five-membered chelates are inactive in this transformation. Computational studies suggest that the C(sp3)-H bond activation is the rate-limiting step in both cases. The C(sp3)-H bond activation with a five-membered chelate is unfavorable by 7.7 kcal/mol compared to the corresponding six-membered chelate with Pd(II). Two factors cause the difference: (1) the dimeric Pd species with five-membered chelation square-planar structure is more stable than that with six-membered chelation by 2.0 kcal/mol; (2) steric repulsion between the ArF group of the substrate and the quinoline group of the acetyl-protected aminomethyl quinoline ligand destabilizes the five-membered chelate transition structure by 5.7 kcal/mol. The six-membered chelate of Pd(II) with an acetyl-protected aminoethyl quinoline ligand orients the ligand away from the ArF group of the substrate and alleviates the steric repulsion.
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