A synthetic anionic clay, hydrotalcite (), promotes the epoxidation of electron-deficientalkenes with H2O2. With open-chain, α,β-unsaturated carbonyl compounds 3-hydroxy-1,2-dioxolanes are also obtained.
合成阴离子粘土水滑石()可以促进缺电子烯烃与H 2 O 2的环氧化。用开链,也可得到α,β-不饱和羰基化合物3-羟基-1,2-二氧戊环。
Synthetic studies on O-heterocycles via cycloadditions. Part 2. Adducts from styrene oxides
作者:Paul Clawson、Patricia M. Lunn、Donald A. Whiting
DOI:10.1039/p19900000159
日期:——
The styreneoxides (14) and (15), bearing electron-withdrawing functions, readily undergo thermal and photochemical (triplet sensitised) dipolar cycloadditions with simple electron-deficient olefins, regioselectively in the case of methyl acrylate. However, cycloadditions with 5-arylbutenolides as dipolarophiles, required for lignan synthesis, could not be effected in significant yield. A new short
Facile Epoxidation of Alumina-Supported Electrophilic Alkenes and Montmorillonite-Supported Electrophilic Alkenes with Sodium Hypochlorite
作者:André Foucaud、Médard Bakouetila
DOI:10.1055/s-1987-28104
日期:——
Alkenes gem-substituted by two electron-withdrawing substituents, dispersed on alumina or montmorillonite, are conveniently epoxided by sodium hypochlorite. A mixture of aldehyde and methylcyanoacetate or malononitrile, treated with alumina and sodium hypochlorite gives the corresponding epoxide in good yield.
Consecutive oxygen-based oxidations convert amines to α-cyanoepoxides
作者:Dmitry B. Ushakov、Kerry Gilmore、Peter H. Seeberger
DOI:10.1039/c4cc04932b
日期:——
Tri- or tetrasubstituted alpha-cyanoepoxides can be rapidly prepared from unactivated amines and malononitrile or methyl cyanoacetate when singlet oxygen, produced in a continuous-flow photoreactor, serves as an oxidant and in situ peroxide source. The hydrogen peroxide generated in amine oxidation epoxidizes an electron deficient olefin intermediate, formed by deaminative Mannich coupling. The corresponding
Chiral urea-catalyzed enantioselective epoxidation of α, β-unsaturated esters
作者:Nan Ji、Qinqin Tian、Qingqing Yang、Minghua Li、Wei He
DOI:10.1016/j.tetlet.2021.152909
日期:2021.3
A highly enantioselectiveepoxidation of trans-α-cyano-α, β-unsaturated esters has been described by using cinchona alkaloid-derived urea and H2O2 as the organocatalysts and oxidant, giving chiral glycidic ester derivatives containing cyano groups in good yields (up to 95%) with excellent enantioselectivities (up to 97% ee). A plausible transition state was also proposed.