Hydroxynitrile lyase-catalyzed addition of HCN to 2-substituted cyclopentanones
作者:Christoph Kobler、Franz Effenberger
DOI:10.1016/j.tetasy.2004.10.010
日期:2004.11
stereoselectivity of hydroxynitrile lyases (HNLs) catalyzed addition of HCN to a variety of monosubstituted cyclopentanones yielding the corresponding cyanohydrins is presented. With PaHNL from bitter almond as catalyst, the HCN addition to 2-alkyl cyclopentanones 1b–d is highly (R)-selective, leading to the cis-(1R,2S)- and trans-(1R,2R)-diastereomers. The addition to the sterically less demanding methyl compound
Studies Toward the Diastereoselective Reduction of 2-Alkoxycarbonyl-2-allyl-cyclopentanone Derivatives with Boron Hydrides
作者:Carlos A. M. Fraga、Eliezer J. Barreiro
DOI:10.1080/00397919508012677
日期:1995.4
Abstract The reduction of 2-alkoxycarbonyl-2-allyl-cyclopentanone derivatives with inexpensive boron hydrides were studied showing that this process depend on chelation factors instead steric ones, affording the isomeric alcohols 2a and 3a with high diastereomeric excess.
Iron(iii) catalysis of the Michael reaction of 1,3-dicarbonyl compounds and enones
作者:Jens Christoffers
DOI:10.1039/a700838d
日期:——
Iron(III) chloride hexahydrate catalyses the Michael
reaction of β-dicarbonyl compounds and enones under mild and neutral
conditions with excellent yields and product selectivity.
Densely functionalized, annulated dihydrofuran derivatives are prepared by a cerium-catalyzed aerobic oxidation reaction. The operationally sim¬ple trans¬for¬ma¬tion is environmentally and economically benign, since the pre¬catalyst CeCl3 ∙ 7 H2O is non-toxic and cheap and the oxidant is simply dioxygen from air. Starting ma¬terials are β-oxoesters and silylenolethers, the latter derived from acetoacetate
Catalytic asymmetric interrupted Attanasi reaction: access to fused 2,3-dihydropyrroles with vicinal quaternary carbons
作者:Yun-Xuan Chen、Tian-Jiao Han、Xiao Xiao、Min-Can Wang、Guang-Jian Mei
DOI:10.1039/d3cc02172f
日期:——
The first catalyticasymmetric interrupted Attanasi reaction has been established. Under the catalysis of a bifunctional organocatalyst, the condensation of cyclic β-keto esters with azoalkenes readily occurred, delivering a variety of bicyclic fused 2,3-dihydropyrroles with vicinal quaternary stereogenic centers in good yields and with good to excellent enantioselectivities (27 examples, up to 96%