Download Recent Advance in Silver-Mediated Chemistry

Recent Advance in Silver-Mediated Chemistry
Special edition on coinage metals, Chem. Rev. 2008, 108, 2793-3442.
A Larger Picture of Silver
Ag (Latin: argentum, from the ancient greek:
argentos, from argeis, "white, shining" )
Oxidation state : +1, +2, +3
Borderline between main group elements and transition metals.
Low Solubility Strong interactions with halogens, but low solubility of the corresponding
salt.
Alkynophilicity Due to d10 electronic configuration, with low-lying empty orbitals of π systems.
Reinforced by f orbitals.
Price For 1 mmole of the corresponding chloride (Aldrich, in CHF):
IrCl3 (93.9) > RhCl3 (72.6) ~ AuCl3 (70.5) > PtCl4 (64.5) > PdCl2 (23.5) > AgCl (1.3)
A Larger Picture of Silver
Lewis acidity Can act both as σ−Lewis acid and π-Lewis acid.
σ-Coordination preferred over π-coordination, with a preference for nitrogen over
oxygen donor.
Figure 2. Computed heats of formation (B3LYP/SDD, kcal mol-1)
of various substrates with AgCl
Yamamoto. Y., J.Org.Chem. 2007, 72, 7817.
A Larger Picture of Silver: Oxidation Processes
- Ag-Alumina: Industrial formation of ethylene oxide, precursor to ethylene glycol.
7 H2C=CH2 + 6 O2 → 6 C2H4O + 2 CO2 + 2 H2O
Industrial formation of formaldehyde.
2 CH3OH + O2 → 2 H2CO + 2 H2O
- Tollen’s reagent: Ag(NH3)2NO3 (test for aldehyde)
Positive result: formation of Ag (s)
Topics of This Review
Part 1 Coupling Reactions Promoted by Silver Salts
Part 2 Asymmetric Reactions
Part 3 Group-transfer Reactions
Νο π-Lewis acid mediated reaction of silver will be discussed here (discussed previously by P. Mateo).
Part 1: Coupling Reactions Promoted by Silver Salts
Two main applications of silver salt in coupling reactions:
(i) They can abstract halides from organometallic intermediates, rendering the metal
(Pd) more electropositive and opening a vacant site in the coordination sphere. In
these cases, the main role is thus to form insoluble silver halides while activating
the actual catalytic species.
Common additives in Heck, Suzuki, Sonogashira, Stille, Hiyama coupling
(ii)
They can produce organosilver species, which can either react as such or more
often be transmetalated to various metals or organometallics, especially
organopalladium intermediates.
Weibel, J.-M.; Blanc, A.; Pale, P., Chem. Rev. 2008, 108, 3149.
Heck Coupling Promoted by Silver Salts
insoluble silver halides
Complexation facilited by cationic palladium
Weibel, J.-M.; Blanc, A.; Pale, P., Chem. Rev. 2008, 108, 3149.
Heck Coupling Promoted by Silver Salts
Selectivity achieved through complexation of the second double bond:
(1) Weibel, J.-M.; Blanc, A.; Pale, P., Chem. Rev. 2008, 108, 3149. (2) Madin, A.; Overman, L. E. Tet. Lett. 1992, 33, 4859.
Suzuki Coupling Promoted by Silver Salts
Acceleration effect of silver salt in the transmetalation:
(1) Weibel, J.-M.; Blanc, A.; Pale, P., Chem. Rev. 2008, 108, 3149. (2) Kishi, Y. et al., J. Am. Chem. Soc. 1987, 109, 4756.
Sonogashira Coupling Promoted by Silver Salts
Formation of a alkynyl silver complex proposed:
(109Ag NMR)
(1) Weibel, J.-M.; Blanc, A.; Pale, P., Chem. Rev. 2008, 108, 3149. (2) Bertus, P.; Dillinger, S.; Pale, P. Org. Lett. 2001, 3, 1661.
Part 2: Asymmetric Reactions
σ- and π-Lewis acidity of silver can easily be used, mostly through the use of N-containing chiral
ligand.
Figure 2. Computed heats of formation (B3LYP/SDD, kcal mol-1)
of various substrates with AgCl
Potential in any reactions which involve N-complexation of a Lewis acid prior to reaction.
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132.
Asymmetric [3+2] Cycloaddition
Endo selective
Amino phosphine ligands
(1) Complexation of the chiral silver
catalyst to the imino ester,
(2) Deprotonation
(3) [3+2] Cycloaddition
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Chen, C.; Li, X.; Schreiber, S. L. J. Am. Chem. Soc. 2003, 125, 10174.
Asymmetric [3+2] Cycloaddition
Reversal of selectivity through Hbonding with the dipolarophile
(1) Lie, Y.-X., J. Am. Chem. Soc. 2007, 129, 751. (2) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132.
Asymmetric [3+2] Cycloaddition
With Munchone, exo-selectivity achieved
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Peddibhotla, S.; Tepe, J. J. Am. Chem. Soc. 2004, 126, 12776.
Asymmetric Hetero Diels-Alder
Through complexation of the Ag to the imine
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Josephsohn, N. S.; Snapper, M. L.; Hoveyda, A. H. J. Am. Chem.
Soc. 2003, 125, 4018. (3) Yao, S.; Johansenn, M.; Hazell, R.. G.; Jorgensen, K. A. Angew. Chem. Int. Ed. 1998, 37, 3121. (4) Kawasaki,
M.; Yamamoto, H. J. Am. Chem. Soc. 2006, 128, 16482.
[2+2] Cycloaddition
Silver-activation of the alkene/alkyne proposed by
the author
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Sweis, R. F.; Schramm, M. P.; Kozmin, S. A. J. Am. Chem. Soc.
2004, 126, 7442.
[2+2] Cycloaddition
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Nakamura, I.; Nemoto, T.; Yamamoto, Y.; de Meijere, A. Angew.
Chem. Int. Ed. 2006, 45, 5176.
Asymmetric Mannich Reactions
Catalytic enantioselective synthesis of βamino carbonyls
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Josephsohn, N. S.; Carswell, E. L.; Snapper, M. L.; Hoveyda, A. H.
Org. Lett. 2005, 7, 2711.
Asymmetric Mannich Reactions
- Complexation of the chelated Ag+ to the
imine
- Addition of the silyl enol ether
- Internal desilylation
- 1 equivalent of i-PrOH necessary to undergo
desilylation
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Josephsohn, N. S.; Carswell, E. L.; Snapper, M. L.; Hoveyda, A. H.
Org. Lett. 2005, 7, 2711.
Part 3: Group- Transfer Reactions
(1) Carbene
New developpement in group-transfer reactions based on:
(2) Nitrene
(3) Silylene
Ambigous mode of activation proposed since silver is oxo-, aza- and carbophilic.
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Rasika, H. V., Lovely, C. J. Chem. Rev. 2008, 108, 3223.
Carbene- Transfer- Buchner Reaction
(1) Rasika, H. V., Lovely, C. J. Chem. Rev. 2008, 108, 3223.
Carbene- Transfer- Buchner Reaction
When conducted in CH2Cl2, 15-25% of this
product obtained:
CO Et
2
Cl
Cl
For 11d, 5% of this impureties was obtained:
(1) Rasika, H. V., Lovely, C. J. Chem. Rev. 2008, 108, 3223.
Cl
CO2Et
Carbene- Transfer- C-X Addition- Rearrangement
(1) Rasika, H. V., Lovely, C. J. Chem. Rev. 2008, 108, 3223.
Carbene- Transfer- C-X Addition- Rearrangement
(1) Rasika, H. V., Lovely, C. J. Chem. Rev. 2008, 108, 3223.
Carbene- Transfer- Catalyzed Cyclopropanation
Donor/acceptor carbenoid working in
cyclopropanation with silver
(1) Rasika, H. V., Lovely, C. J. Chem. Rev. 2008, 108, 3223. (2) Thompson, J. L.; Davies, H. M. L. J. Am. Chem. Soc. 2007, 129, 6090.
Nitrene- Transfer- Aziridination
Short metal-metal distance
Accessible coordination site
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Cui, Y.; He, C.; J Am. Chem. Soc. 2003, 125, 16202.
Nitrene- Transfer- C-H Insertion
(1)
(2)
Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132.
(2) Cui, Y.; He, C.; Angew. Chem. Int. Ed. 2004, 43, 4210.
Silylene- Transfer- Silacyclopropanation
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Cirakovic, J.; Driver, T. G.; Woerpel, K. A., J Am. Chem. Soc. 2002,
124, 9370.
Silylene- Transfer- Silacyclopropanation
- Phosphine added in order to study the
mechanism - slow the process (10 °C)
- Only reversible with bis-cyclic
silacyclopropane, with cyclohexane
quicker
Proved reactive intermediate
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Driver, T. G.; Woerpel, K. A., J Am. Chem. Soc. 2004, 126, 9993.
Silylene- Transfer- Silacyclopropanation
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Cirakovic, J.; Driver, T. G.; Woerpel, K. A., J Am. Chem. Soc. 2002,
124, 9370. (3) Franz,. A. K.; Woerpel, K. A., Angew. Chem. Int. Ed. 2000, 39, 4295.
Silylene- Transfer- Silacyclopropanation
(1) Naodovic, M., Yamamoto, H., Chem. Rev. 2008, 108, 3132. (2) Cirakovic, J.; Driver, T. G.; Woerpel, K. A., J Am. Chem. Soc. 2002,
124, 9370. (3) Calad, S. A.; Woerpel, K. A., J Am. Chem. Soc. 2005, 127, 2046.
Conclusion
High potential for new reactions based on silver, in oxidation, alkene-alkyne activation, metalcatalyzed coupling, assymetric, group-transfer reactions.