Highly Regioselective Catalytic Oxidative Coupling Reactions: Synthetic and Mechanistic Investigations
作者:Kami L. Hull、Erica L. Lanni、Melanie S. Sanford
DOI:10.1021/ja065718e
日期:2006.11.1
A highly efficient and regioselective Pd-catalyzed method for the oxidative coupling of arylpyridine derivatives is reported. Remarkably, the reactions proceed at room temperature and are compatible with diverse functionalities, including aryl halides and thiophenes. Mechanistic studies suggest that these transformations proceed via a previously unprecedented mechanism involving two different pyridine-directed C-H activation reactions-one at a PdII center and one at PdIV.
Cu(II)-mediated oxidative dimerization of 2-phenylpyridine derivatives
A Cu(II)/I-2-mecliated C-H bond activation is described. A variety of 2-phenylpyridine derivatives are oxidatively dimerized at the ortho-position of the phenyl ring in which a net loss of two hydrogen atoms results ill [lie formation of a biaryl compound via a double C-H activation/C-C bond-forming process. Moderate functional group tolerance was observed on both the aryl and the pyridyl rings. A single electron transfer (SET) or electrophilic metalation process for iodination followed by Ullmann Coupling Of the intermediate iodinated product is proposed as the operating mechanism for the dimerization process. (C) 2008 Published by Ekevier Ltd.