Further Information
Literature
Related Reactions
Aldol Addition
Mukaiyama Aldol Addition
The use of silyl enol ethers as an enolate equivalent in Lewis acid-catalyzed aldol additions. The trimethylsilyl group is thought of as a sterically demanding hydrogen equivalent that activates the enol and traps the aldol hydroxyl.
Mechanism
The open transition state is preferred, but the outcome of the reaction (syn/anti) depends on the size of substituents and on the Lewis acid. New modified protocols allow syn- or anti-selective transformations and even the selective preparation of enantiomers.
Transition-state for syn-selective transformations:
Recent Literature
BINAP/AgOTf/KF/18-Crown-6 as New Bifunctional Catalysts for Asymmetric
Sakurai-Hosomi Allylation and Mukaiyama Aldol Reaction
M. Wadamoto, N. Ozasa, A. Yanagisawa, H. Yamamoto,
J. Org. Chem., 2003, 68, 5593-5601.
Bismuth Triflate-Chiral Bipyridine Complexes as Water-Compatible Chiral
Lewis Acids
S. Kobayashi, T. Ogino, H. Shimizu, S. Ishikawa, T. Hamada, K. Manabe, Org. Lett., 2005, 7, 4729-4731.
Aluminum Bis(trifluoromethylsulfonyl)amides: New Highly Efficient and
Remarkably Versatile Catalysts for C - C Bond Formation Reactions
A. Marx, H. Yamamoto, Angew. Chem. Int. Ed., 2000, 39,
178-181.
Strong Counteranion Effects on the Catalytic Activity of Cationic Silicon
Lewis Acids in Mukaiyama Aldol and Diels-Alder Reactions
L.-B. Han, C.-Q. Zhao, J. Org. Chem., 2005, 70, 10121-10123.
In the presence of only 0.5 mol % of
an N-heterocyclic carbene, various aldehydes and 2,2,2-trifluoroacetophenone underwent Mukaiyama aldol reactions in THF with
a trimethylsilyl ketene acetal as well as with a trimethylsilyl enol ether to afford aldol
adducts in good yields. These conditions are extremely mild and operationally
simple and tolerate various functional groups.
J. J. Song, Z. Tan, J. T. Reeves, N. K. Yee, C. H. Senanayake, Org. Lett., 2007,
9, 1013-1016.
Lewis Base Activation of Lewis Acids: Catalytic, Enantioselective Addition
of Silyl Ketene Acetals to Aldehydes
S. E. Denmark, G. L. Beutner, T. Wynn, M. D. Eastgate, J. Am. Chem. Soc., 2005, 127, 3774-3789.
Catalytic Enantio- and Diastereoselective Aldol Reactions of Glycine-Derived
Silicon Enolate with Aldehydes: An Efficient Approach to the Asymmetric
Synthesis of anti-β-Hydroxy-α-Amino Acid Derivatives
J. Kobayashi, M. Nakamura, Y. Mori, Y. Yamashita, S. Kobayashi, J. Am. Chem. Soc., 2004, 126, 9192-9193.
Lewis Base Activation of Lewis Acids. Vinylogous Aldol Addition Reactions of
Conjugated N,O-Silyl Ketene Acetals to Aldehydes
S. E. Denmark, J. R. Heemstra, Jr., J. Am. Chem. Soc., 2006, 128, 1038-1039.
