90269-46-8Relevant academic research and scientific papers
Rhodium-catalyzed allyl transfer from homoallyl alcohols to aldehydes via retro-allylation followed by isomerization into ketones
Takada, Yuko,Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
, p. 2515 - 2517 (2006)
Retro-allylation of homoallyl alcohol by rhodium catalysis occurs to generate allylrhodium species. This allylrhodium reacts with aldehydes to give the corresponding secondary alcohols in situ. Isomerization of these alcohols proceeds in the same pots to furnish the corresponding saturated ketones in good yields.
Substituted phenyl ethers
-
, (2008/06/13)
Compounds of the formula STR1 in which R1, R2, R3, R4, R5 and R6 are as defined in claim 1 can be used as agrochemical active ingredients and can be prepared in a manner known per se.
Kinetics and Mechanism of the Reaction of Ketones with Lithium Reagents in Cyclohexane
Al-Aseer, Munther A.,Smith, Stanley G.
, p. 2608 - 2613 (2007/10/02)
The kinetics of the reaction of sec-BuLi and n-BuLi with several substituted phenyl sec-butyl ketones in cyclohexane at 25.0 deg C have been examined by stopped-flow infrared spectroscopy.Experiments in which reacting solutions of the ketones were scanned
Enolisation baso-catalysee des cetones : 2e partie : Racemisation de methyl-2 phenyl-1 butanones-1 substituees en milieux fortement basiques
Aurelly, Michele,Lamaty, Gerard
, p. 389 - 394 (2007/10/02)
The base-catalyzed enolization of a ketone transforms the latter into an enolate ion via an activated complex in which a proton α to the carbonyl is transferred between its original site and the base catalyst.The position of the proton in the activated complex along the reaction pathway between the substrate and the base depends on the basic strengths of these entities.Some authors have suggested a regular variation of the position of the proton with the basicity of the medium, which led us to further investigate this question.We chose to use the Hammett correlation.As a matter of fact, Hammett's slope ρ correlates with the charge density on the substrate in the activated complex, therefore it was reasonable to think that the ρ values would be a function of the distance between the proton and the substrate.The experimental part of this work consists of the determination of enolization rates of substituted aromatic ketones in media of various basicities, in order to plot the correlation log10 k = (?).For practical reasons, we chose to study the racemization rates of five optically active substituted 2-methyl-1-phenyl-butan-1-ones.These ketones were synthesized by Friedel-Crafts reactions, which explains the fact that the substituents on the aromatic ring are essentially electrodonating : p-OCH3, 3',4'-dimethyl, p-CH3, H, p-Cl.The reaction media used are, by increasing basicities : water-dioxane 64/36 v/v + OH-, water-ethanol 1/2 + OH-/C2H5O-, ethanol + C2H5O-, ethanol-DMSO 2/1, 1/1 and 1/2 + C2H5O-, ethanol-HMPA 1/2 + C2H5O-.The ρ values in these solvents are respectively : 1.1, 2.0, 2.1, 2.2, 2.3, 2.4, 2.1.They are all positive.One finds that : 1. in strongly aqueous media, water-dioxane 64/36 and water (see preceding paper), ρ values are close to + 1, whereas in the other (slightly or non aqueous) media, they are of about + 2.This can be due to the nature of the base (OH- in one case and C2H5O- in the other), to the amount of water in the solvent, or to the nature of the organic solvent.One can also contemplate, as some authors did, the possibility of a change in the reaction mechanism according to the nature of the base. 2. if we take into account the experimental error on ρ values, there is only little (if any) change in the latter with the alkalinity of the medium (H functions for the various solvents used vary approximately from 14 to 19, which corresponds to an appreciable alkalinity increase).The conclusion is that the substrate retains the same charge density in the activated complex, the geometry of which consequently is the same in all media.According to the slope of the straight line log10 kobs = (H), which is 0.41 the proton being transferred in the activated complex could be slightly closer to the substrate than to the attacking base.
