43050-16-4Relevant academic research and scientific papers
Fluorinated chiral secondary amines as catalysts for epoxidation of olefins with oxone
Ho, Chun-Yu,Chen, Ying-Chun,Wong, Man-Kin,Yang, Dan
, p. 898 - 906 (2007/10/03)
(Chemical Equation Presented) We have synthesized a series of chiral cyclic secondary amines having different substitution patterns and have screened them as catalysts for the asymmetric epoxidation of olefins using Oxone. The highest enantiomeric excess (61%) occurred for the epoxidation of 1-phenylcyclohexene catalyzed by a secondary amine bearing a fluorine atom at the β-position relative to the amino center. Our experimental results provide further support to the notion that the amine plays a dual role - as a phase transfer catalyst and an Oxone activator - in these epoxidation reactions. The slightly acidic reaction conditions we employed in this work obviate the need to preform ammonium salts, which are the actual catalysts that mediate the epoxidations.
Enantioselective protonation of samarium enolates derived from α- heterosubstituted ketones and lactone by SmI2-mediated reduction
Nakamura, Yutaka,Takeuchi, Seiji,Ohgo, Yoshiaki,Yamaoka, Makoto,Yoshida, Akihiro,Mikami, Koichi
, p. 4595 - 4620 (2007/10/03)
SmI2-mediated reductive cleavage of α-heterosubstituents of α-alkyl or α-aryl ketones and lactone gave the corresponding 'thermodynamic samarium enolates'. Enantioselective protonation of the samarium enolates with C2- symmetric chiral diols afforded the corresponding ketones and lactone in moderate to high enantioselectivities.
Acid-catalyzed phenylcyclohexene oxide hydrolysis: Role of para-phenyl substituent on syn:anti hydration ratio
Doan, Lanxuan,Bradley, Kevin,Gerdes, Sonya,Whalen, Dale L.
, p. 6227 - 6234 (2007/10/03)
Rate and product studies of the hydronium ion-catalyzed hydrolysis of 1- phenylcyclohexene oxide and its p-methoxy and p-methyl derivatives in 1:9 dioxane-water solutions were carried out under conditions in which the diol products are stable. It is shown that the cis:trans diol ratio from hydrolysis of this series of epoxides does not systematically increase with the electron-donating ability of the para-substituent, contrary to conclusions in the literature. The equilibrium constants and rates for acid- catalyzed approach to equilibration of cis- and trans-1-(p- methoxyphenyl)cyclohexane-1,2-diol and of cis- and trans-1-(p- methylphenyl)cyclohexane-1,2-diol were measured, and the cis-diol was determined to be the more stable isomer in each case. An intermediate in the acid-catalyzed hydrolysis of 1-(p-methoxyphenyl)cyclohexene oxide is trapped, after its rate-limiting formation, by azide ion. For a series of 1- arylcyclohexene oxides, results are interpreted in terms of a mechanism in which there is a discrete carbocation intermediate, and products are determined solely by the partitioning reactions of this intermediate, with the pathway leading to the more stable product being energetically favored.
