Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, USA.
J Am Chem Soc. 2011 Mar 30;133(12):4455-64. doi: 10.1021/ja1097918. Epub 2011 Mar 7.
This paper presents a detailed investigation of the factors controlling site selectivity in the Pd-mediated oxidative coupling of 1,3-disubstituted and 1,2,3-trisubstituted arenes (aryl-H) with cyclometalating substrates (L~C-H). The influence of both the concentration and the steric/electronic properties of the quinone promoter are studied in detail. In addition, the effect of steric/electronic modulation of the carboxylate ligand is discussed. Finally, we demonstrate that substitution of the carboxylate for a carbonate X-type ligand leads to a complete reversal in site selectivity for many arene substrates. The origins of these trends in site selectivity are discussed in the context of the mechanism of Pd-catalyzed oxidative cross-coupling.
本文详细研究了钯介导的 1,3-二取代和 1,2,3-三取代芳烃（芳基-H）与环金属化底物（L~C-H）的氧化偶联中控制反应选择性的因素。详细研究了醌促进剂的浓度和空间/电子性质的影响。此外，还讨论了羧酸配体的空间/电子调节效应。最后，我们证明了对于许多芳基底物，羧酸配体取代碳酸盐 X 型配体可导致反应选择性的完全反转。讨论了这些反应选择性趋势的起源，其涉及钯催化氧化交叉偶联的机制。
