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- Title
Slow Reactant-Water Exchange and High Catalytic Performance of Water-Tolerant Lewis Acids.
- Authors
Koito, Yusuke; Nakajima, Kiyotaka; Kobayashi, Hisayoshi; Hasegawa, Ryota; Kitano, Masaaki; Hara, Michikazu
- Abstract
31P nuclear magnetic resonance (NMR) spectroscopic measurement with trimethylphosphine oxide (TMPO) was applied to evaluate the Lewis acid catalysis of various metal triflates in water. The original 31P NMR chemical shift and line width of TMPO is changed by the direct interaction of TMPO molecules with the Lewis acid sites of metal triflates. [Sc(OTf)3] and [In(OTf)3] had larger changes in 31P chemical shift and line width by formation of the Lewis acid-TMPO complex than other metal triflates. It originates from the strong interaction between the Lewis acid and TMPO, which results in higher stability of [Sc(OTf)3TMPO] and [In(OTf)3TMPO] complexes than other metal triflate-TMPO complexes. The catalytic activities of [Sc(OTf)3] and [In(OTf)3] for Lewis acid-catalyzed reactions with carbonyl compounds in water were far superior to the other metal triflates, which indicates that the high stability of metal triflate-carbonyl compound complexes cause high catalytic performance for these reactions. Density functional theory (DFT) calculation suggests that low LUMO levels of [Sc(OTf)3] and [In(OTf)3] would be responsible for the formation of stable coordination intermediate with nucleophilic reactant in water.
- Subjects
BIOCHEMICAL substrates; LEWIS acids; NUCLEAR magnetic resonance; TRIMETHYLPHOSPHINE; TRIFLATE compounds; CARBONYL compounds
- Publication
Chemistry - A European Journal, 2014, Vol 20, Issue 26, p8068
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201400240