A highly enantioselective asymmetric Darzens reaction catalysed by proline based efficient organocatalysts for the synthesis of di- and tri-substituted epoxides
A new class of easily available and readily tunable proline based chiral organocatalysts was found to efficiently catalyse an unprecedented highly enantioselective asymmetric Darzens reaction of α-chloro ketones and substituted α-chloro ketones with various aldehydes, which directly produces optically active di- and tri-substituted chiral epoxides with higher product yields (up to 97 %) and excellent
Solvent microstructure effect on reaction stereochemistry; ring opening of chalcone oxides
作者:Dana Durham、Charles A. Kingsbury
DOI:10.1039/p29860000923
日期:——
The stereochemistry and kinetics of acid-catalysed ring-opening reactions of epoxides are reported. Predominant inversion is found in the usual hydroxylic solvents. As the nucleophilicity of the solvent diminishes and acidity increases, the stereochemistry changes to predominant retention. Electron-donating substituents also tend to favour retention. In mixed solvents, the solvent microstructure is
Visible-Light-Driven Epoxyacylation and Hydroacylation of Olefins Using Methylene Blue/Persulfate System in Water
作者:Gabriela F. P. de Souza、Juliano A. Bonacin、Airton G. Salles
DOI:10.1021/acs.joc.8b01026
日期:2018.8.3
olefins in water using methylene blue as photoredox catalyst and persulfate as oxidant is reported. In this unprecedented unified approach, two different transformations are accomplished using only one set of reagents. The method has a broad scope spanning a range of aromatic and aliphatic aldehydes as well as conjugated and nonconjugated olefins to deliver ketones and epoxyketones from abundant and
1,1,2,2‐Tetrahydroperoxy‐1,2‐diphenylethane was used for the efficient and metal‐free epoxidation of various α,β‐unsaturated ketones, carried out under mild alkaline conditions at room temperature.