2017年11月
DFT and AFIR Study on the Mechanism and the Origin of Enantioselectivity in Iron-Catalyzed Cross-Coupling Reactions
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
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- 巻
- 139
- 号
- 45
- 開始ページ
- 16117
- 終了ページ
- 16125
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1021/jacs.7b05917
- 出版者・発行元
- AMER CHEMICAL SOC
The mechanism of the full catalytic cycle for Fe-chiral-bisphosphine-catalyzed cross-coupling reaction between alkyl halides and Grignard reagents (Nakamura and co-workers, J. Am. Chem. Soc. 2015, 137, 7128) was rationalized by using density functional theory (DFT) and multicomponent artificial force-induced reaction (MC-AFIR) methods. The computed mechanism consists of (a) C-Cl activation, (b) transmetalation, (c) C-Fe bond formation, and (d) C-C bond formation through reductive elimination. Our survey on the prereactant complexes suggested that formation of Fe-II(BenzP*)Ph-2 and Fe-I(BenzP*)Ph complexes are thermodynamically feasible. Fe-I(BenzP*)Cl complex is the active intermediate for C-Cl activation. Fe-II(BenzP*)Ph-2 complex can be formed if the concentration of Grignard reagent is high. However, it leads to biphenyl (byproduct) instead of the cross-coupling product. This explains why slow addition of Grignard reagent is critical for the cross-coupling reaction. The MC-AFIR method was used for systematic determination of transition states for C-Fe bond formation and C-C bond formation starting from the key intermediate Fe-II(BenzP*)PhCl. According to our detailed analysis, C-C bond formation is the selectivity-determining step. The computed enantiomeric ratio of 95:5 is in good agreement with the experimental ratio (90:10). Energy decomposition analysis suggested that the origin of the enantioselectivity is the deformation of Ph-ligand in Fe-complex, which is induced by the bulky tert-butyl group of BenzP* ligand. Our study provides important mechanistic insights for the cross-coupling reaction between alkyl halides and Grignard reagents and guides the design of efficient Fe-based catalysts for cross-coupling reactions.
- リンク情報
- ID情報
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- DOI : 10.1021/jacs.7b05917
- ISSN : 0002-7863
- Web of Science ID : WOS:000415785900024