Abstract
The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various α,β-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3-As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-β-azido-α-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samarium azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.
| Original language | English |
|---|---|
| Pages (from-to) | 2147-2155 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 127 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Feb 23 2005 |
| Externally published | Yes |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry
Cite this
Dynamic ligand exchange of the lanthanide complex leading to structural and functional transformation : One-pot sequential catalytic asymmetric epoxidation-regioselective epoxide-opening process. / Tosaki, Shin Ya; Tsuji, Riichiro; Ohshima, Takashi; Shibasaki, Masakatsu.
In: Journal of the American Chemical Society, Vol. 127, No. 7, 23.02.2005, p. 2147-2155.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Dynamic ligand exchange of the lanthanide complex leading to structural and functional transformation
T2 - One-pot sequential catalytic asymmetric epoxidation-regioselective epoxide-opening process
AU - Tosaki, Shin Ya
AU - Tsuji, Riichiro
AU - Ohshima, Takashi
AU - Shibasaki, Masakatsu
PY - 2005/2/23
Y1 - 2005/2/23
N2 - The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various α,β-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3-As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-β-azido-α-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samarium azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.
AB - The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various α,β-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3-As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-β-azido-α-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samarium azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.
UR - http://www.scopus.com/inward/record.url?scp=13944249839&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=13944249839&partnerID=8YFLogxK
U2 - 10.1021/ja043770+
DO - 10.1021/ja043770+
M3 - Article
C2 - 15713092
AN - SCOPUS:13944249839
VL - 127
SP - 2147
EP - 2155
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 7
ER -