Room temperature ionic liquids (ILs) are used as a green recyclable reaction media for the α-monohalogenation of 1,3-diketones, β-keto-esters and cyclic ketones with N-halosuccinimides in excellent yields in the absence of a catalyst. The recovered ionic liquid was reused five to six times with consistent activity.
We report the metal-catalyzed α-hydroxylation of a variety of cyclic and acyclic β-dicarbonylcompounds by molecularoxygen. The decisive advantage of this new method is the use of catalytic amounts of the nontoxic cerium salt CeCl3·7H2O in 2-propanol at ambient temperature. Most of the cyclic substrates 4a−4i give high yields of analytically pure products 5a−5i, and the workup procedure is simple
Mild α-Halogenation Reactions of 1,3-Dicarbonyl Compounds Catalyzed by Lewis Acids
作者:Dan Yang、Yi-Long Yan、Bob Lui
DOI:10.1021/jo026025t
日期:2002.10.1
Lewis acid Mg(ClO4)2, combined with NBS, in CH3CN or EtOAc provided mild and fast bromination of 1,3-dicarbonyl compounds. In particular, this protocol could be applied to the alpha-monobromination of alpha-unsubstituted beta-keto esters. Similar Lewis acid catalysis was also extended to the alpha-chlorination and iodination of 1,3-dicarbonyl compounds with NCS and NIS, respectively.
Iron-catalyzed hydroxylation of β-ketoesters with hydrogen peroxide as oxidant
作者:Dongmei Li、Kristin Schröder、Bianca Bitterlich、Man Kin Tse、Matthias Beller
DOI:10.1016/j.tetlet.2008.07.157
日期:2008.10
The hydroxylation of β-ketoesters was studied using simple iron catalysts and 30 wt % hydrogenperoxide as the terminal oxidant. The highest activity and yield were achieved in the presence of iron(III) chloride. Cyclic β-ketoesters could be smoothly hydroxylated in 75–90% yield. For linear β-ketoester and β-ketoamide, the chloro-substituted products were obtained.