Categories: O-Si Bond Formation >
Synthesis of silyl enol ethers and related compounds
Recent Literature
Various ionic liquids have been tested for the
preparation of silyl enol ethers from aldehydes and ketones with
(bistrimethylsilyl)acetamide (BSA). Yields have been strongly influenced by the
nature of the cation of the ionic liquid.
M. Smietana, C. Mioskowski, Org. Lett., 2001, 3,
1037-1039.
N-Heterocyclic carbenes (NHCs) catalyze the silyl transfer from trialkylsilyl
ketene acetals to ketones. A series of enolizable ketones as well as
cyclohexanecarboxaldehyde were efficiently converted into the corresponding
silyl enol ethers at 23°C in THF.
J. J. Song, Z. Tan, J. T. Reeves, D. R. Fandrick, N. K. Yee, C. H. Senanayake, Org. Lett., 2008,
10, 877-880.
An efficient, practical, robust method for the regio- and stereoselective
preparation of ketene trimethylsilyl acetals derived from tert-butyl
esters can be performed under convenient reaction conditions: LDA-TMSCl, 0-5 °C,
and cyclopentyl methyl ether (CPME) as solvent. The stereocontrolled preparation
of highly reactive β-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol
ethers is also described.
T. Okabayashi, A. Iida, K. Takai, Y. Nawate, T. Misaki, Y. Tanabe, J. Org. Chem., 2007,
72, 8142-8145.
T. Okabayashi, A. Iida, K. Takai, Y. Nawate, T. Misaki, Y. Tanabe, J. Org. Chem., 2007,
72, 8142-8145.
N,O-Silyl dienyl ketene acetals are useful reagents for highly
enantioselective vinylogous aldol additions to various aldehydes in the presence of SiCl4 and the catalytic action of
a chiral
phosphoramide.
S. E. Denmark, J. R. Heemstra, Jr., J. Am. Chem. Soc.,
2006, 128, 1038-1039.
1-Siloxy-1-alkenylcopper species were generated by 1,2-Csp2-to-O
silyl migration of the copper enolates of acyltriphenylsilanes. The
alkenylcopper species reacted with methyl, benzyl, allylic, tributylstannyl
halides and in the presence of Pd(0) catalyst with aryl and alkenyl iodides
to give geometrically pure (Z)-enol silyl ethers.
A. Tsubouchi, K. Onishi, T. Takeda, J. Am. Chem. Soc., 2006, 128, 14268-14269.
Palladium-catalyzed hydrosilylation of α,β-unsaturated ketones and cyclopropyl
ketones with hydrosilanes gives (Z)-silyl enolates in good yields.
Y. Sumida, H. Yorimitsu, K. Oshima, J. Org. Chem., 2009,
74, 7986-7989.
A three-component nickel-catalyzed coupling of enals, alkynes, and silanes forms
an enol silane and a trisubstituted alkene with >98:2 stereoselectivity. The
reaction tolerates a broad range of functionality including aldehydes, ketones,
esters, free hydroxyls, and basic secondary amines.
A. Herath, J. Montgomery, J. Am. Chem. Soc., 2008,
130, 8132-8133.
Related
Lithium diisopropylamide (LDA) promotes virtually quantitative conversion of
allylic ethers to (Z)-propenyl ethers with very high stereoselectivity in
THF at room temperature. The reaction time for the conversion increases with
more sterically hindered allylic ethers.
C. Su, P. G. Williard, Org. Lett., 2010,
12, 5378-5381.
