57956-45-3Relevant articles and documents
Mesoporous aluminosilicate-catalyzed Mukaiyama aldol reaction of aldehydes and acetals
Ito, Suguru,Tanuma, Kenji,Matsuda, Kohei,Hayashi, Akira,Komai, Hirotomo,Kubota, Yoshihiro,Asami, Masatoshi
, p. 8498 - 8504 (2014/12/11)
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.
Mukaiyama Aldol Reactions Catalyzed by Zirconocene Bis(triflate) Complexes: Stereochemistry and Mechanisms for C-C Bond Formation
Lin, Shuqiong,Bondar, Georgiy V.,Levy, Christopher J.,Collins, Scott
, p. 1885 - 1892 (2007/10/03)
The aldol condensations of α- and β-(benzyloxy) aldehydes with enol silanes, catalyzed by Cp2Zr(OTf)2THF or Cp2Zr(OTf)2, in a variety of solvents were studied. The simple diastereoselectivity of these reactions is modest and comparable to that observed using simple aldehydes of similar steric requirements. Studies have revealed that TMSOTf is directly produced on reaction with the zirconocene catalyst with the enol silane in nitroalkane solvent or is formed during catalysis in dichloromethane solution. Although TMSOTf is known to catalyze cross-aldol reactions under these conditions, the rate of this process is not always competitive with that observed using the zirconocene catalysts. In particular, sterically unhindered or aromatic aldehydes react via a mechanism that appears to be mainly Zr-catalyzed, based on both the difference in rate between Zr- and Si-mediated reactions as well as differences in enol silane/silyl triflate reactivity in crossover-type experiments. With sterically hindered aldehydes in dichloromethane or nitromethane, catalysis is mediated by Si. The Zr-catalyzed process occurs via formation of a Zr-aldolate complex from aldehyde and enol silane, with liberation of TMSOTf, followed by rate-limiting O-silylation of the metal aldolate by TMSOTf, as revealed by both model studies and in situ monitoring during catalysis.
oxotitanium. A Chemoselective and Efficient Catalyst for Aldol-type Reaction of Ketene Silyl Acetals with Aldehydes
Hara, Ryuichiro,Mukaiyama, Teruaki
, p. 1909 - 1912 (2007/10/02)
In the presence of catalytic amount of oxotitanium, ketene silyl acetals smoothly react with aldehydes to afford the corresponding β-hydroxy carboxylic esters in good yields under mild conditions.According to this procedure, a
