71640-83-0Relevant articles and documents
Reversed stereochemical control in the presence of CeCl3 and TiCl4 in the Lewis acid mediated reduction of α-alkyl-β-keto esters by metal hydrides. A general methodology for the diastereoselective synthesis of syn- and anti-α-alkyl-β
Marcantoni, Enrico,Alessandrini, Sara,Malavolta, Marco,Bartoli, Giuseppe,Bellucci, Maria Cristina,Sambri, Letizia,Dalpozzo, Renato
, p. 1986 - 1992 (1999)
The Lewis acid-mediated reduction of α-alkyl-β-keto esters has been shown to proceed by different stereochemical control depending on the nature of the metal atom. Strongly chelating TiCl4 led to the syn isomer in high diastereomeric excess in
Chiral α-branched benzylic carbocations: Diastereoselective intermolecular reactions with arene nucleophiles and NMR spectroscopic studies
Muehlthau, Friedrich,Stadler, Daniel,Goeppert, Alain,Olah, George A.,Prakash, G. K. Surya,Bach, Thorsten
, p. 9668 - 9675 (2007/10/03)
The chiral benzylic alcohols 1-6 were prepared and subjected to S N1-type displacement reactions with various arene nucleophiles in acidic medium. Under optimized conditions (HBF4·OEt 2, CH2Cl2, -78 °
Mechanism of Nucleophilic Addition to the Carbonyl Group. Part III. Evidence for the Reactant-like Nature of the Transition State in the LiAlH4 Reduction of Alkyl Aryl Ketones.
Arjona, Odon,Perez-Ossorio, Rafael,Perez-Rubalcaba, Alfredo,Quiroga, Maria L.,Romero, Dolores
, p. 2351 - 2371 (2007/10/02)
A Hammett-type free energy relationship is established for the LiAlH4 reduction of 1-(X-phenyl)-2,3,3-trimethyl-1-butanones (X = H, p-F, m-F, p-Me, m-Me, p-MeO, m-MeO, p-NMe2 and m-NMe2) in Et2O at 30 deg C.A ρ value of 1.77 has been obtained.Rate ratios
Stereochemistry of Addition to the Carbonyl Group. Part 17. Study of the Factors affecting Asymmetric Induction in Condensation Reactions of Methyl- and Phenyl-magnesium Bromide with Chiral Carbonyl Compounds
Arjona, Odon,Perez-Ossorio, Rafael,Perez-Rubalcaba, Alfredo,Quiroga, Maria L.
, p. 597 - 603 (2007/10/02)
The dependence of the stereoselectivity upon the nature of the chiral carbonyl compound , the solvent, and the concentration ofthe reactive species for various condensation reactions of phenyl- and methyl-magnesium bromide at 30 degC is reported.The stereochemical results have been interpreted on the basis of the generalized Curtin-Hammett principle and according to a trigonal-type transition state (Perez-Ossorio model).No effect of the concentration of the reactive species on the product ratio was observed.An unexpected influence of the solvent was observed in the condensation of (4) with phenylmagnesium bromide.A good linear correlation between stereoselectivity and the ET parameter of the solvent was obtained.The explanation offered here takes into account the steric selection of the transition states and a further differentiating effect of the solvent polarity on them.A slight influence of solvent polarity on reactions of (5) with Grinard reagents was also noticed.