Presentation on theme: "1 Chiral Anion-Mediated Asymmetric Ion Pairing Chemistry Reporter: Zhi-Yong Han 2010-12-31."— Presentation transcript:
1 Chiral Anion-Mediated Asymmetric Ion Pairing Chemistry Reporter: Zhi-Yong Han 2010-12-31
Background and Introduction Ion Pair ( by Bjerrum in 1926) A pair of oppositely charged ions held together by Coulomb attraction without formation of a covalent bond. contact (tight or intimate) ion pair solvent separated ion pair solvent-shared ion pair “Strict” electrostatic ion pair H-bonded charge-assisted supramolecular entity Ion Pairing Chemistry Brønsted acid catalysis
Structure and properties of anionic counterions Chiral Anions Carboxylate and sulfonate anions Borate anions phosphate anions Hexacoordinated phosphorus anions Other anionic structures
Carboxylate and sulfonate anions Application: enantiomeric resolutions Water-soluble sulfonated resorcarenes commercially available cyclic polyacids
E. N. Jacobsen, J. Am. Chem. Soc., 2007, 129, 13404–13405.
E. N. Jacobsen, J. Am. Chem. Soc., 2008, 130, 7198–7199.
VAPOL-Boron Lewis Acid? Up to 98% ee Jon C. Antilla and William D. Wulff* J. Am. Chem. Soc. 1999, 121, 5099-5100 Catalyst structure not determined
Wulff, W. D. Eur. J. Org. Chem. 2007, 206, 8–2071. VAPOL-Boron Lewis Acid?
Scope and Mechanistic Studies Wulff, W. D. Chem.sEur. J. 2008, 14, 3785–3803.
Catalyst structure determination No non-linear effect. The results suggest that it is likely that only one molecule of the ligand is involved in the active catalyst. Wulff, W. D. Chem.sEur. J. 2008, 14, 3785–3803.
Catalyst structure determination Wulff, W. D. Chem.sEur. J. 2008, 14, 3785–3803.