作者:Thomas W. Lyons、Kami L. Hull、Melanie S. Sanford                                    
                                    
                                        DOI:10.1021/ja1097918
                                    
                                    
                                        日期:2011.3.30
                                    
                                    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 similar to 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.