Opticallyactive N,N′-ethylenebis(α-alkoxycarbonyl-β-ketoimine) was found to be a new class of effective ligand of manganese(III) complexcatalyst for the asymmetric aerobicepoxidation of simple olefins, such as 1,2-dihydronaphthalene derivatives, to afford the corresponding opticallyactive epoxides with good to high enantioselectivities.
Transesterification of β-ketoesters with various alcohols has been effected by N,N-diethylaminopropylated silica gel (NDEAP) as a catalyst in refluxing xylene. Generality of the reaction was demonstrated by successful transesterification of olefinic alcohols, tertiary alcohols and alcohols having acid- or base-sensitive substituents. The catalyst has been efficiently recycled more than five times without any re-activation.
Enhanced enantiocontrol in catalytic metal carbene transformations with dirhodium (II) tetrakis[methyl 2-oxooxazolidin-4(S)-carboxylate], Rh2(4S-MEOX)4
作者:Michael P. Doyle、Alexey B. Dyatkin、Marina N. Protopopova、Chien I. Yang、Charla S. Miertschin、William R. Winchester、Stanley H. Simonsen、Vincent Lynch、Ratna Ghosh
DOI:10.1002/recl.19951140407
日期:——
for dirhodium(II) tetrakis[methyl 2-oxooxazolidin-4(S)-carboxylate], Rh2(4S-MEOX)4, and the related dirhodium(II) tetrakis[methyl 5(R)-methyl-2-oxooxazolidin-4(S)-carboxylate], Rh2(4S-THREOX)4, are reported. Comparison is made between these 2-oxooxazolidin-ligated dirhodium(II) catalysts for metalcarbenetransformations and those with comparable 2-oxopyrrolidine ligands, especially dirhodium(II) tetrakis[methyl