Preparation of Acyloins by Cerium-Catalyzed, Direct Hydroxylation ofβ-Dicarbonyl Compounds with Molecular Oxygen
作者:Jens Christoffers、Thomas Werner、Sven Unger、Wolfgang Frey
DOI:10.1002/ejoc.200390075
日期:2003.2
We report the metal-catalyzed α-hydroxylation of a variety of cyclic and acyclic β-dicarbonyl compounds by molecular oxygen. 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
我们报告了金属催化的分子氧对各种环状和非环状 β-二羰基化合物的 α-羟基化。这种新方法的决定性优势是在环境温度下在 2-丙醇中使用催化量的无毒铈盐 CeCl3·7H2O。大多数环状底物 4a-4i 产生高产率的分析纯产物 5a-5i,后处理程序是通过硅胶简单过滤。然而,无环二羰基化合物 4j-4p 的氧化伴随着副反应和分解,显着降低了产物 5j-5p 的产率。提出的机制与实验结果一致,特别是观察到的氧摄取。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)