Ligand-less palladium-catalyzed direct 5-arylation of thiophenes at low catalyst loadings
作者:Julien Roger、Franc Požgan、Henri Doucet
DOI:10.1039/b819912d
日期:——
Ligand-less Pd(OAc)2 provides a very efficient catalyst for the direct5-arylation of thiophenederivatives. With this catalyst, a low palladium concentration (0.1–0.001 mol%) should be employed in order to obtain high yields of coupling products. At higher concentrations a fast formation of inactive “Pd black” generally occurs. Substrates/catalysts ratios up to 100000 can be employed with the most
The directarylation of activated thiophenes was accomplished in moderate to good yields using a Heck-type reaction with the mixture of Pd(OAc)2 and n-Bu4NBr as a catalyticsystem. This new arylation method is applied to different derivatives and has proved to be compatible with sensitive functional groups. Furthermore, the substituent nature and position on the thiophene moiety influence the cross
使用Heck型反应,将Pd(OAc)2和n- Bu 4 NBr的混合物作为催化体系,可以中等至良好的产率完成活化噻吩的直接芳基化反应。这种新的芳基化方法适用于不同的衍生物,并已证明与敏感的官能团兼容。此外,噻吩部分上的取代基性质和位置影响交叉偶联。特别是当杂环在第2位被吸电子基团取代时,该取代是区域特异性的。
Directthiophenearylation using a Heck-type reaction with as catalytic system is reported. Reactions with 2- and 3-substituted thiophenes have shown that substituent nature and position influence the cross-coupling. In particular, the substitution is regiospecific when the heterocycle is 2-substituted with an electron withdrawing group.