Metal-Free Oxidative Coupling Reactions via σ-Iodonium Intermediates: The Efficient Synthesis of Bithiophenes Using Hypervalent Iodine Reagents
作者:Koji Morimoto、Tomofumi Nakae、Nobutaka Yamaoka、Toshifumi Dohi、Yasuyuki Kita
DOI:10.1002/ejoc.201100969
日期:2011.11
The direct oxidative biaryl couplingreaction is an attractive tool for environmentally benign green chemistry. A novel direct method for the synthesis of bithiophene using a hypervalentiodinereagent has been developed. The reaction mechanism has also been investigated, casting light on the reaction intermediate and revealing the reactivity with iodonium salts.
The hypervalent iodine-induced arene cross coupling via a single-electron-transfer (SET) oxidation process could proceed in some extent even in heteroaromatic compounds, that is, several types thiophenes 1, using alkyl benzenes 2 as coupling partners. The structure of the obtainable heteroaromatic biaryl products could be elaborated by utilizing the known metal-catalyzed coupling technology, i.e., Negishi cross coupling, for the synthesis of multiple arylated (bi)thiophenes.