文献类型：期刊文献

英文题名：Palladium-Catalyzed Reductive Homocoupling of Aromatic Halides and Oxidation of Alcohols

作者：Zeng, Minfeng;Du, Yijun;Shao, Linjun;Qi, Chenze[1];Zhang, Xian-Man

机构：[1]Univ Shaoxing, Inst Appl Chem, Shaoxing 312000, Zhejiang, Peoples R China; Univ Shaoxing, Dept Chem, Shaoxing 312000, Zhejiang, Peoples R China

年份：2010

卷号：75

期号：8

起止页码：2556

外文期刊名：JOURNAL OF ORGANIC CHEMISTRY

收录：SCI-EXPANDED(收录号：WOS:000276556600016)、、EI(收录号：20101612867968)、Scopus(收录号：2-s2.0-77950967748)、WOS、CCR-EXPANDED(收录号：WOS:000276556600016)

基金：This work was generously supported by the Natural Science Foundation of Zhejiang Province (no. Y4080450), People's Republic of China and Shaoxing University. We would like to thank Dr. Z. Fang for his kind help for the XPS measurements and helpful discussions.

语种：英文

外文关键词：Aromatization - Catalysis - Catalysts - Iron compounds - Organometallics - Oxidation - Palladium - Purification - Reagents - Redox reactions - Solvents

外文摘要：Palladium-catalyzed reductive homocoupling of aromatic halides can be performed in alcohol solutions without any auxiliary reducing, reagents. Pd(dppf)Cl-2 [dppl = l,l'-bis(diphenylphosphino)ferrocene] has been shown as the most effective catalyst among the palladium catalysts screened for the model reductive homocoupling of iodobenzene in alcoholic solutions. The reduction of iodobenzene is stoichiometrically coupled with the oxidation of solvent alcohol (3-pentanol). The X-ray photoelectron spectroscopic (XPS) studies clearly indicate that the oxidation of solvent alcohol molecules is involved with the in situ regeneration of the reductive Pd(dppf) active species, indicating that the solvent alcohol also reacts as a reducing reagent for the reductive homocoupling of aromatic halides. Elimination of the external reducing reagents will simplify the product separation and purification. Base is essential for the success of the Pd(dppf)Cl-2-catalyzed redox reaction as 2 molar equiv of base is needed to neutralize the acid byproduct formed. Biaryls are the predominant products for the Pd(dppf)Cl-2-catalyzed reductions of the unsubstituted aromatic halides in 3-pentanol solution, whereas the dehalogenation products are predominant for the Pd(dppf)Cl-2-catalyzed reductions of the substituted aromatic halides. The reaction mechanisms have been discussed for the palladium-mediated concomitant reduction of aromatic halides and oxidation of alcohols without any auxiliary reductants and oxidants.