187848-84-6Relevant articles and documents
Chiral phosphoramide-catalyzed aldol additions of ketone enolates. Preparative aspects
Denmark, Scott E.,Stavenger, Robert A.,Wong, Ken-Tsung,Su, Xiping
, p. 4982 - 4991 (1999)
Trichlorosilyl enolates of ketones (enoxytrichlorosilanes) were demonstrated to be highly reactive aldol addition reagents. Trichlorosilyl enolates of cyclohexanone (E-enolate) and propiophenone (Z-enolate) reacted readily at room temperature with a wide
Iron- and bismuth-catalyzed asymmetric mukaiyama aldol reactions in aqueous media
Kitanosono, Taku,Ollevier, Thierry,Kobayashi, Shu
supporting information, p. 3051 - 3062 (2014/01/06)
We have developed asymmetric Mukaiyama aldol reactions of silicon enolates with aldehydes catalyzed by chiral FeII and BiIII complexes. Although previous reactions often required relatively harsh conditions, such as strictly anhydrous conditions, very low temperatures (-78 °C), etc., the reactions reported herein proceeded in the presence of water at 0 °C. To find appropriate chiral water-compatible Lewis acids for the Mukaiyama aldol reaction, many Lewis acids were screened in combination with chiral bipyridine L1, which had previously been found to be a suitable chiral ligand in aqueous media. Three types of chiral catalysts that consisted of a FeII or BiIII metal salt, a chiral ligand (L1), and an additive have been discovered and a wide variety of substrates (silicon enolates and aldehydes) reacted to afford the desired aldol products in high yields with high diastereo- and enantioselectivities through an appropriate selection of one of the three catalytic systems. Mechanistic studies elucidated the coordination environments around the FeII and BiIII centers and the effect of additives on the chiral catalysis. Notably, both Bronsted acids and bases worked as efficient additives in the Fe II-catalyzed reactions. The assumed catalytic cycle and transition states indicated important roles of water in these efficient asymmetric Mukaiyama aldol reactions in aqueous media with the broadly applicable and versatile catalytic systems. Copyright
Iron(II) and zinc(II) complexes with designed pybox ligand for asymmetric aqueous Mukaiyama-aldol reactions
Jankowska, Joanna,Paradowska, Joanna,Rakiel, Bartosz,Mlynarski, Jacek
, p. 2228 - 2231 (2007/10/03)
An iron(II) complex with a hindered hydroxyethyl-pybox (he-pybox) ligand shows improved catalytic activity and enantioselectivity for asymmetric Mukaiyama-aldol reactions in aqueous media. This water-stable chiral Lewis acid promotes condensation of aroma
Zn(pybox)-complex-catalyzed asymmetric aqueous Mukaiyama-Aldol reactions
Jankowska, Joanna,Mlynarski, Jacek
, p. 1317 - 1321 (2007/10/03)
Catalytic asymmetric aldol reactions in aqueous media have been developed using chiral zinc complex. The aldol products have been obtained in high yields, high diastereocontrol, and good level of enantioselectivity. Various aromatic and α,β-unsaturated al
Aqueous asymmetric Mukaiyama aldol reaction catalyzed by chiral gallium Lewis acid with trost-type semi-crown ligands
Li, Hui-Jing,Tian, Hong-Yu,Wu, Yan-Chao,Chen, Yong-Jun,Liu, Li,Wang, Dong,Li, Chao-Jun
, p. 1247 - 1256 (2007/10/03)
The combination of Ga(OTf)3 with chiral semi-crown ligands (1a-e) generates highly effective chiral gallium Lewis acid catalysts for aqueous asymmetric aldol reactions of aromatic silyl enol ethers with aldehydes. A ligand-acceleration effect was observed. Water is essential for obtaining high diastereoselectivity and enantioselectivity. The p-phenyl substituent in aromatic silyl enol. ether (2 h) plays an important role and increases the enantioselectivity up to 95% ee. Although aliphatic silyl enol ethers provided low enantioselectivities and silylketene acetal is easily hydrolyzed in aqueous alcohol, the aldol reactions of silylketene thioacetal (12) with aldehydes in the presence of gallium-Lewis acid catalysts give the β-hydroxy thioester with reasonable yields and high diastereo- (up to 99:1) and enantioselectivities (up to 96% ee).
Asymmetric mukaiyama-aldol reaction in aqueous media promoted by zinc-based chiral lewis acids
Mlynarski, Jacek,Jankowska, Joanna
, p. 521 - 525 (2007/10/03)
Asymmetric aldol reactions in aqueous media have been realized by using zinc-based chiral Lewis acids. The aldol products have been obtained with high yield, diastereocontrol and a good level of enantioselectivity. The reactivity of both acetophenone and
Lewis base-promoted aldol reaction of dimethylsilyl enolates in aqueous dimethylformamide: Use of calcium chloride as a Lewis base catalyst
Miura, Katsukiyo,Nakagawa, Takahiro,Hosomi, Akira
, p. 536 - 537 (2007/10/03)
In the presence of CaCl2, dimethylsilyl (DMS) enolates smoothly reacted with aldehydes under mild conditions to give aldol adducts in good to high yields. The catalytic activities of various metal and tetrabutylammonium salts have revealed that CaCl2 works as a Lewis base catalyst to activate DMS enolates. The CaCl2-promoted reaction proceeded even in the presence of water or in pure water. This catalytic system was applicable to the aldol reaction with aqueous aldehydes such as formalin. Copyright
