An efficient phosphine-free direct C–Harylation of thiophenes at the α-position has been developed at low catalyst loading of bis(alkoxo)palladium complex (Cat.I, 0.1–0.2 mol %). The developed synthetic method can be applied to the synthesis of α-aryl/heteroaryl thiophenes from aryl or heteroaryl bromides in good to excellent yields and is compatible with the substrates bearing electron-donating or
A palladium NNC-pincer complex efficiently catalyzed the direct arylation of thiophene derivatives with extremely low palladium loadings of the order of parts per million. Thus, the reaction of various thiophenes with aryl bromides in the presence of 25–100 mol ppm of chlorido[(2-phenyl-κ-C 2)-9-phenyl-1,10-phenanthroline-κ2-N,N′]palladium(II) NNC-pincer complex, K2CO3, and pivalic acid in N,N-dimethylacetamide
Generation of metalated thiophenes with Grignard reagent and catalytic secondary amine for the cross coupling reaction with aryl halides
作者:Shota Tanaka、Daiki Tanaka、Atsushi Sugie、Atsunori Mori
DOI:10.1016/j.tetlet.2011.12.108
日期:2012.2
The reaction of thiophene derivatives with Grignard reagent (EtMgCl) and a catalytic amount of amine (Cy2NH) induced the metalation at the α-position. Following addition of several aryl halides in the presence of a nickel or palladium catalyst afforded C–H arylated products in good to excellent yields. The method was successfully applied to facile synthesis of differently-substituted 2,5-diarylthiophenes