Mesoporous aluminosilicate-catalyzed Mukaiyama aldol reaction of aldehydes and acetals
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both aldehydes and acetals with silyl enol ethers or ketene silyl acetals to give the corresponding aldol adducts in moderate to high yields. The remarkable high catalytic activity of Al-MCM-41 over amorphous silica-alumina and aluminum-free mesoporous silicate was observed in the reaction. The solid acid catalyst could be recovered easily by filtration and the recovered catalyst was reusable in the same reactions without a significant loss of catalytic activity.
Cationic iridium complex is a new and efficient Lewis acid catalyst for aldol and Mannich reactions
A cationic iridium complex [Ir(cod)2]SbF6 was found to be a new and efficient Lewis acid catalyst for Mukaiyama aldol and Mannich reactions. Aldehydes react smoothly with silyl enol ethers to give β-siloxy ketones in the presence of 0.5 mol % of [Ir(cod)2]SbF6. The reaction of N-alkyl arylaldimines with ketene silyl acetals in the presence of 5 mol % [Ir(cod)2]SbF6/P(OPh)3 gave β-amino esters. After Mannich reaction was complete, stirring of the reaction mixture for 24 h led to cyclization to give β-lactam. The reaction of N-aryl benzaldimine with silyl enol ether derived from acetophenone gave a tetrahydroquinoline derivative as a single diastereomer.
Mukaiyama aldol reaction catalyzed by mesoporous aluminosilicate
In the presence of a mesoporous aluminosilicate Al-MCM-41, aldol reaction of various silyl enol ethers with both aromatic and aliphatic aldehydes proceeded under mild reaction conditions to afford the corresponding O-silylated aldol adducts in high yields. The solid acid catalyst was easily recovered and reusable three times. Copyright
[HC(py)3W(NO)2(CO)](SbF6)2 as a Lewis acid precursor in additions of silylated C-nucleophiles to carbonyl compounds
[HC(py)3W(NO)2(CO)](SbF6)2 is a feasible Lewis acid catalyst precursor for the addition of silylated C-nucleophiles to carbonyl compounds. The O-silylated adducts are easily isolated without aqueous work-up and
Faller,Gundersen, Lise-Lotte
p. 2275 - 2278
(2007/10/02)
Reversal Phenomena of the Preferential Activation of Aldehydes to the Corresponding Acetals under Non-Basic Conditions. The Chemoselective Aldol Reaction of Aldehydes with t-Butyldimethylsilyl Enol Ethers Using TBSCl-InCl3 as a Catalyst
In the presence of a catalytic amount of t-butyldimethylsilyl chloride (TBSCl) and indium(III) chloride (InCl3), aldehydes smoothly react with t-butyldimethylsilyl enol ethers to afford the corresponding aldol adducts in good yields whereas acetals do not
Mukaiyama, Teruaki,Ohno, Takashi,Han, Jeong Sik,Kobayashi, Shu
p. 949 - 952
(2007/10/02)
New role of tin(II) compounds in organic synthesis
Three new carbon-carbon bond forming reactions by the use of new catalyst systems involving tin(II) compounds are described in this article.The aldol reaction of silyl enol ethers with acetals or aldehydes and the Michael reaction of silyl enol ethers wit
Mukaiyama, Teruaki,Kobayashi, Shu
p. 39 - 52
(2007/10/02)
An Efficient and Extremly Mild Catalyst System, Combined Use of Trityl Chloride and Tin(II) Chloride, in the Aldol and Michael Reactions
The aldol reaction of silyl enol ethers with acetals or aldehydes, and the Michael reaction of silyl enol ethrs with α,β-unsaturated ketones are efficiently catalyzed by the combined use of trityl chloride and tin(II) chloride under extremly mild conditio