Palladium-catalysed direct arylation of 4- or 2-bromobenzenesulfonic acid derivatives in the presence of a variety of heteroaromatics was found to proceed using 0.1–0.5 mol% palladium acetate as the catalyst. However, both the nature and position of the SO2R substituent on such bromobenzenes has an influence on the reaction rates and yields. The presence of SO2Et or SO2NEt2 at the C2 or C4 position of bromobenzene is tolerated. Good results were also obtained from bromobenzene substituted at C4 by SO2NHPh or SO2OPh. On the other hand, the reactions of bromobenzenes bearing either SO2N(Me)CH2Ph or SO2OAr at C2 led in some cases to intramolecular reactions instead of the desired intermolecular couplings. Some reactions were performed in cyclopentyl methyl ether, which can be considered as a green solvent.
使用0.1-0.5%摩尔的
醋酸钯作为催化剂,在多种杂芳环存在下,发现
钯催化的4-或2-
溴苯磺酸衍
生物的直接芳基化反应可以进行。然而,
溴苯上SO2R取代基的性质和位置对反应速率和产率有影响。在
溴苯的C2或C4位置存在SO2Et或SO2NEt2是可以容忍的。在C4位置由SO2NHPh或SO2OPh取代的
溴苯也得到了良好的结果。另一方面,在C2位置带有SO2N(Me)CH2Ph或SO2OAr的
溴苯的反应在某些情况下会导致分子内反应,而不是所期望的分子间偶联。一些反应在环
戊基甲基醚中进行,这种溶剂可以被认为是一种环保溶剂。