A highly selective asymmetric domino allylation of aliphatic ketones is described. When methyl ketones 1a-g, the chiral trimethylsilyl ether 2, and allylsilane 3 react in the presence of catalytic amounts of trifluoromethanesulfonic acid, the homoallylic ethers 4a-g are produced with up to 24:1 diastereoselectivity and 89% yield. Cleavage of the obtained tertiary homoallylic ethers C using lithium or sodium in liquid ammonia gives the homoallytic alcohols 5 in 75 to 95% yield and up to 92% ee. Even ethyl methyl ketone 1a, the most difficult example, showed a stereoselectivity of 9:1 at -78 degrees C and 24:1 at -109 degrees C. In addition, the allylation of protected hydroxyalkyl methyl ketones 7a-j was investigated to give the corresponding homoallylic ethers 8a-j with a diastereoselectivity of up to >24:1 and 98% yield. In contrast, ethyl alkyl ketones 1h-j have a low selectivity.
Reductive Coupling of Allylic Esters with Carbonyl Compounds Mediated by the Mischmetall/[SmI2/Pd0cat.′]cat. System
作者:Sédami Médégan、Florence Hélion、Jean-Louis Namy
DOI:10.1002/ejoc.200500291
日期:2005.11
“two-stage catalysis” has been carried out using SmI2 and Pd(PPh3)4 in catalytic amounts together with mischmetall (an alloy of the light lanthanides) as a co-reductant. A catalytic scheme that takes into account previously reported reactions of SmI2/Pd0cat. and mischmetall/SmI2,cat. systems is proposed. It has also been shown that palladium complexes catalyse the addition of organolanthanide species
Porous and Robust Lanthanide Metal-Organoboron Frameworks as Water Tolerant Lewis Acid Catalysts
作者:Yan Liu、Ke Mo、Yong Cui
DOI:10.1021/ic400598x
日期:2013.9.16
number of isolated Lewisacid B(III) and Ln(III) sites on the pore surfaces. The Nd-MOF assisted with sodium dodecylsulfate was found to be highly effective, recyclable, and reusable heterogeneous catalyst for the carbonyl allylation reaction, the Diels–Alder reaction, and the Strecker-type reaction in water. The transformations were cocatalyzed by Nd(III) and B(III) Lewisacids, with activities much
Asymmetric Allylation of Ketones and Subsequent Tandem Reactions Catalyzed by a Novel Polymer-Supported Titanium-BINOLate Complex
作者:Jagjit Yadav、Gretchen R. Stanton、Xinyuan Fan、Jerome R. Robinson、Eric J. Schelter、Patrick J. Walsh、Miquel A. Pericas
DOI:10.1002/chem.201400204
日期:2014.6.2
asymmetric allylation of ketones. The catalyst showed good activity and excellent enantioselectivity, typically matching the results obtained in the corresponding homogeneous reaction. The allylation reaction mixture could be submitted to epoxidation by simple treatment with tert‐butyl hydroperoxide (TBHP), and the tandem asymmetricallylation epoxidation process led to a highly enantioenriched epoxy alcohol
Lithium Hexafluorophosphate-Catalyzed Efficient Tetrahydropyranylation of Tertiary Alcohols under Mild Reaction Conditions
作者:Tsuneo Sato、Nao Hamada
DOI:10.1055/s-2004-829550
日期:——
Lithium hexafluorophosphate is found to be an efficientcatalyst for the tetrahydropyranylation of tertiary alcohols with dihydropyran under mild reaction conditions.
在温和的反应条件下,六氟磷酸锂被发现是叔醇与二氢吡喃的四氢吡喃化反应的有效催化剂。
Nickel-Catalyzed Reductive Allylation of Ketones with Allylic Carbonates
Nickel-catalyzed efficient umpolung allylation of ketones with allyliccarbonates in the presence of zinc powder is developed, which accommodates a variety of allylic and ketone substrates. Although chiral ligand is necessary for the transformation, no enantioselectivity was observed. Nickel-catalyzed efficient umpolung allylation of ketones with allyliccarbonates in the presence of zinc powder is developed