Mechanistic insights into stereoselective catalysis - The effects of counterions in a CuII-bissulfoximine-catalyzed diels-alder reaction

Bolm, Carsten, Martin, Marc, Gescheidt, Georg, Palivan, Cornelia, Stanoeva, Tsvetanka, Bertagnolli, Helmut, Feth, Martin, Schweiger, Arthur, Mitrikas, George and Harmer, Jeffrey (2007) Mechanistic insights into stereoselective catalysis - The effects of counterions in a CuII-bissulfoximine-catalyzed diels-alder reaction. Chemistry - A European Journal, 13 6: 1842-1850. doi:10.1002/chem.200601086


Author Bolm, Carsten
Martin, Marc
Gescheidt, Georg
Palivan, Cornelia
Stanoeva, Tsvetanka
Bertagnolli, Helmut
Feth, Martin
Schweiger, Arthur
Mitrikas, George
Harmer, Jeffrey
Title Mechanistic insights into stereoselective catalysis - The effects of counterions in a CuII-bissulfoximine-catalyzed diels-alder reaction
Formatted title
Mechanistic insights into stereoselective catalysis - The effects of counterions in a CuII-bissulfoximine-catalyzed diels-alder reaction
Journal name Chemistry - A European Journal   Check publisher's open access policy
ISSN 0947-6539
1521-3765
Publication date 2007-01-12
Year available 2007
Sub-type Article (original research)
DOI 10.1002/chem.200601086
Open Access Status
Volume 13
Issue 6
Start page 1842
End page 1850
Total pages 9
Place of publication Weinheim, Germany
Publisher Wiley
Language eng
Formatted abstract
The initial steps of an enantioselective Diels–Alder reaction catalyzed by a CuII–bissulfoximine complex were followed by EXAFS (EXAFS=extended X-ray absorption fine structure), EPR (EPR=electron paramagnetic resonance) spectroscopy (CW-EPR, FID-detected EPR, pulse ENDOR, HYSCORE; CW=continuous wave; ENDOR=electron nuclear double resonance; HYSCORE=hyperfine sublevel correlation; FID=free induction decay), and UV-visible spectroscopy. The complexes formed between the parent CuX2 (X=Cl, Br, TfO, SbF6) salts, the chiral bissulfoximine ligand (S,S)-1, and N-(1-oxoprop-2-en-1-yl)oxazolidin-2-one (2) as the substrate in CH2Cl2 were investigated in frozen and fluid solution. In all cases, penta- or hexacoordinated CuII centers were established. The complexes with counterions indicating high stereoselectivity (TfO and SbF6) reveal one unique species in which substrate 2 binds to pseudoequatorial positions (via O atoms), shifting the counterions to axial locations. On the other hand, those lacking stereoselectivity (X=Cl and Br) form two species in which the parent halogen anions remain at equatorial positions preventing the formation of geometries compatible with those found for X=TfO and SbF6.
Keyword Bissulfoximine complexes
Catalysis
EPR spectroscopy
EXAFS spectroscopy
HYSCORE spectroscopy
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Advanced Imaging Publications
 
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