Cerium-catalyzed α-Oxidation of β-Dicarbonyl Compounds with Molecular Oxygen
作者:Jens Christoffers、Thomas Werner
DOI:10.1055/s-2002-19331
日期:——
β-Ketoesters and β-diketones are α-hydroxylated by molecularoxygen in the presence of 5 mol% CeCl 3 .7 H 2 O in i-PrOH as solvent. The method is limited to substrates with an α-alkyl substituent. Optimal yields are achieved with cyclic starting materials.
β-酮酯和β-二酮在作为溶剂的 i-PrOH 中,在 5 mol% CeCl 3 .7 H 2 O 存在下被分子氧α-羟基化。该方法仅限于具有 α-烷基取代基的底物。使用环状起始材料可实现最佳产率。
Preparation of Acyloins by Cerium-Catalyzed, Direct Hydroxylation ofβ-Dicarbonyl Compounds with Molecular Oxygen
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
Integration of a Four-Step Reaction into One-Pot under the Coexistence of Silica-Gel-Supported Acid and Base Reagents: Synthesis of Benzo- and Naphthothiophenes Using NaHSO4/SiO2 and Na2CO3/SiO2
reaction proceeded efficiently by introduction of starting materials and reagents in a single reaction vessel. The starting materials were very easy to handle and unpleasant smell of aryl thiols that were used in conventional methods could be avoided. Novel thirty-nine benzo- and naphthothiophenes were synthesized by this method in excellent to fair yields. A four-step synthesis of benzo- and naphthothiophenes