4209-90-9Relevant articles and documents
Ruthenium-Catalyzed Direct Transformation of Alkenyl Oximes to 5-Cyanated Isoxazolines: A Cascade Approach Based on Non-Stabilized Radical Intermediate
Wang, Dan-Jun,Chen, Bei-Yi,Wang, Yi-Qi,Zhang, Xiao-Wei
supporting information, p. 1342 - 1346 (2018/04/02)
A ruthenium-catalyzed ammoxidation of alkenyl oximes under mild and neutural condtions is described. In this method, tert-butyl nitrite plays a dual role, acting as an oxidant as well as a nitrogen source. This reaction avoids using any toxic radical initiators or cyanide reagents. This convenient and practical method offers an easy access to 5-cyanated isoxazolines in good to high yields, and shows good functional group tolerance and high efficiency. It is rather remarkable that this new reaction provides a strategically distinct approach based on non-stabilized radical intermediate and constructs C–O and C≡N triple bonds in a single-step. Moreover, the difunctionalization of unactivated olefins bearing oximes has been realized.
Reactions at interfaces: Oxygenation of n-butyl ligands anchored on silica surfaces with methyl(trifluoromethyl)dioxirane
Mello, Rossella,Martinez-Ferrer, Jaime,Alcalde-Aragones, Ana,Varea, Teresa,Acerete, Rafael,Gonzalez-Nunez, Maria Elena,Asensio, Gregorio
experimental part, p. 10129 - 10139 (2012/02/14)
The oxygenation of n-butyl and n-butoxy chains bonded to silica with methyl(trifluoromethyl)dioxirane (1) revealed the ability of the silica matrix to release electron density toward the reacting C2-H σ-bond through the Si-C1 and Si-O1 σ-bonds connecting the alkyl chain to the surface (silicon β-effect). The silica surface impedes neither the alkyl chain adopting the conformation required for the silicon β-effect nor dioxirane 1 approaching the reactive C2 methylene group. Reaction regioselectivity is insensitive to changes in the solvation of the reacting system, the location of organic ligands on the silica surface, and the H-bonding character of the silica surface. Reaction rates are faster for those organic ligands either within the silica pores or bonded to hydrophilic silica surfaces, which evidence the enhanced molecular dynamics of confined dioxirane 1 and the impact of surface phenomena on the reaction kinetics. The oxygenation of n-butyl and n-butoxy chains carrying trimethylsilyl, trimethoxysilyl, and tert-butyl groups with dioxirane 1 under homogeneous conditions confirms the electronic effects of the silyl substituents and the consequences of steric hindrance on the reaction rate and regioselectivity. Orthosilicic acid esters react preferentially at the methylene group adjacent to the oxygen atom in clear contrast with the reactivity of the carboxylic or sulfonic acid alkyl esters, which efficiently protect this position toward oxidation with 1 (Figure presented).
Acyclic Stereoselection. 17. Simple Diastereoselection in the Addition of Medium- and Long-Chain n-Alkyl Ketone Lithium Enolates to Aldehydes
Heathcock, , Clayton H.,Lampe, John
, p. 4330 - 4337 (2007/10/02)
The n-alkyl tert-butyl ketones 1b-d have been prepared and the stereochemistry of their aldol reaction with benzaldehyde has been investigated.As with ketone 1a, ketones 1b-d give Z-enolates that react with benzaldehyde in THF at -78 deg C to give syn aldols.When the aldol additions are carried out in pentane, the syn aldols are also the kinetic products, but syn-anti equilibration is much more rapid in this solvent; after reaction at 25 deg C for 20 min, ketones 1c and 1d give only the anti aldols 3c and 3d.Aldolate syn-anti equilibration becomes more facile as the size of the α-alkyl group increases.Ketone 14 has been prepared and employed in a synthesis of methyl (+/-)-isocorynomycolate; the crucial aldol addition, leading to β-hydroxyketones 15 and 16, proceeds with kinetic stereoselection of only 4.5:1.
