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Chiral Anion-Mediated Asymmetric Ion Pairing Chemistry

Chiral Anion-Mediated Asymmetric Ion Pairing Chemistry. Reporter: Zhi-Yong Han 2010-12-31. Br ø nsted acid catalysis. Ion Pairing Chemistry. H-bonded charge-assisted supramolecular entity. “Strict” electrostatic ion pair. Background and Introduction. Ion Pair ( by Bjerrum in 1926)

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Chiral Anion-Mediated Asymmetric Ion Pairing Chemistry

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  1. Chiral Anion-Mediated Asymmetric Ion Pairing Chemistry Reporter: Zhi-Yong Han 2010-12-31

  2. Brønsted acid catalysis Ion Pairing Chemistry H-bonded charge-assisted supramolecular entity “Strict” electrostatic ion pair 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

  3. Carboxylate and sulfonate anions Borate anions Chiral Anions phosphate anions Hexacoordinated phosphorus anions Other anionic structures Structure and properties of anionic counterions

  4. Carboxylate and sulfonate anions commercially available cyclic polyacids Water-soluble sulfonated resorcarenes Application: enantiomeric resolutions

  5. Borate anions Mariappan Periasamy, J. Org. Chem. 1999, 64, 7643-7645

  6. Borate anions Up to 34% ee B. A. Arndtsen, Org. Lett., 2000, 2, 4165–4168.

  7. Borate anions ee < 26% Bruce A. Arndtsen Organometallics 2004, 23, 2838-2840

  8. Borate anions A+ : Ag, Na, Et2NH2+, Et3NH + A. Nelson, Tetrahedron: Asymmetry, 2003, 14, 1995–2004.

  9. Up to 84% ee Borate anions Walter Leitner Angew. Chem. Int. Ed. 2006, 45, 3689 –3692

  10. Borate anions Hisashi Yamamoto J. Am. Chem. Soc. 1998, 120, 6920-6930

  11. Borate anions Gary B. Schuster J. Am. Chem. Soc. 1998, 120, 1705-1717

  12. B. List, Angew. Chem., Int. Ed., 2006, 45, 4193–4195 B. List, Angew. Chem., Int. Ed., 2008, 47, 1119–1122.

  13. F. D. Toste, Science, 2007, 317, 496–499.

  14. E. N. Jacobsen, J. Am. Chem. Soc., 2007, 129, 13404–13405.

  15. E. N. Jacobsen, J. Am. Chem. Soc., 2008, 130, 7198–7199.

  16. VAPOL-Boron Lewis Acid? Catalyst structure not determined Up to 98% ee Jon C. Antilla and William D. Wulff* J. Am. Chem. Soc. 1999, 121, 5099-5100

  17. VAPOL-Boron Lewis Acid? Wulff, W. D. Eur. J. Org. Chem. 2007, 206, 8–2071.

  18. Scope and Mechanistic Studies Wulff, W. D. Chem.sEur. J. 2008, 14, 3785–3803.

  19. 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.

  20. Catalyst structure determination Wulff, W. D. Chem.sEur. J. 2008, 14, 3785–3803.

  21. Evidence: Boroxinate Based Brønsted Acid

  22. To form catalyst 10, >3 fold of borane was needed William D. Wulff J. AM. CHEM. SOC. 2009, 131, 15615–15617

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