3 Features of Gold Catalysis π-acidity: soft Lewis acid, preferentially activate π-systems Au I and Au III Au I : d 10, linear bicoordinate geometry, difficult in asymmetric catalysis Noβ-H elimination Reluctant to undergo oxidative addition and reductive elimination
4 Relativistic Effect Lower 6s and 6p, higher 5d Pyykko, P. et al. Acc. Chem. Res. 1979, 12, 276.
5 Origin of π –acidity and Alkynophilicity π -acidity of R 3 PAu + 1)lower LUMO 2) poor back donation Alkynophilicity 1) kinetic in origin 2) LUMO of alkyne is lower Hertwig, R. H. et al. J. Phys. Chem. 1996, 100, 12253. Toste, F. D. et al. Nature. 2007, 446, 395. ΔG -10 kcal/mol
36 Gold and Palladium Combined for Cross-Coupling Hashmi, A. S. K. et al. Angew. Chem. Int. Ed. 2009, 48, 8283. Blum, S. D. et al. Organometallics. 2009, 28, 1275.
37 Summary π-acidity reactivity Complexity 1. substrate design 2. coupled with known reactivity (Nazarov, cycloaddition, carbocation) 3. tandem Gold catalyzed coupling reaction Combine π-acidity reactivity and coupling reaction 1. Generate more complexity 2. from stoichiometric to catalytic
38 Acknowledgement Professor Weiping Tang Tang Group Practice talk attendees Katherine Myhre Jenny Werness Wei Zhang Renhe Liu Dr. Suqing Zheng Xiaoxun Li Dr. Min Zhang Patrick Robichaux Na Liu Kyle Dekorver Tianning Diao
39 Goddard, W. A.; Toste, F. D. et al. Org. Lett. 2009, 11, 4798. Mascarenas, J. L. et al. J. Am. Chem. Soc. 2009, 131, 13020.
Relativistic Effect m=m 0 /[1-(v/c) 2 ] 1/2 r decrease as m increase v increase, m increase, radius decrease, s and p orbital lower, d higher Unusual higher electronegativity, ionization energy, lower 6s and 6p (LUMO), higher 5d, strong Au-L bond Pyykko, P. et al. Acc. Chem. Res. 1979, 12, 276.
General Reactivities of Gold Catalysis π- Acidity: Traditional organometallic reactivity: Oxidative addition and reductive elimination Transmetallation C-H activation: Hydrogenation and Oxidation