The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfercatalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetricinduction. It was found that the position of the substituents in the aromatic ring of the chalcone
Diaryl-2-pyrrolidinemethanols catalyzed enantioselective epoxidation of α,β-enones: new insight into the effect of structural modification of the catalyst on reaction efficiency
作者:Alessandra Lattanzi、Alessio Russo
DOI:10.1016/j.tet.2006.10.005
日期:2006.12
Catalytic enantioselectiveepoxidation of α,β-unsaturated ketones promoted by diaryl-2-pyrrolidinemethanols and tert-butyl hydroperoxide (TBHP) is described. Investigation on structural modifications of the diaryl-2-pyrrolidinemethanols showed that fine tuning of the stereoelectronics of the substituents on the aryl moiety is important to achieve high efficiency. By employing a structurally optimized
Enantioselective epoxidation of α,β-enones promoted by (1R,3S,4S)-2-azanorbornyl-3-methanol as an organocatalyst
作者:Jun Lu、Yun-He Xu、Feng Liu、Teck-Peng Loh
DOI:10.1016/j.tetlet.2008.07.175
日期:2008.10
(1R,3S,4S)-2-Azanorbornyl-3-methanol was synthesized form (R)-1-phenylethylamine and used as a catalyst for the enantioselectiveepoxidation of α,β-enones to afford the corresponding epoxides in good yields and high enantioselectivities at room temperature.
Chiral cyclic α-amino acid containing oligopeptide catalyzed highly enantioselective epoxidation of α,β-unsaturatedketones and the α-helical secondary structure of the peptide catalyst were revealed by X-ray crystallographic analysis.
commonly used hydrogen peroxide and hypochlorite for the phase-transfer catalytic epoxidation of α,β-enones under non-aqueous conditions. A variety of chalcone derivatives give the corresponding epoxides with quantitative conversion and satisfactory yields in just a few hours under mild conditions. An asymmetric variant of the epoxidation can be carried out in the presence of chiral N-anthracenylmethylcinchonidine