Palladium-Catalysed C2 or C5 Direct Arylation of 3-Substituted Thiophenes with Aryl Bromides
作者:Henri Doucet、Jia Dong、David Roy、Reny Roy、Marina Ionita
DOI:10.1055/s-0030-1260213
日期:2011.11
catalyst for the direct arylation of 3-substituted thiophene derivatives. The regioselectivity of the arylation strongly depends on the thiophene substituent and also on the nature of the aryl bromide. When using 3-formyl, 3-cyano, 3-methyl, 3-hydroxymethyl or 3-bromothiophene, the 2-arylated thiophenes were obtained with 76-95% regioselectivity; whereas, the arylation of 3-formylthiophene diethylacetal
钯(OAc)2发现/ dppb体系是3-取代的噻吩衍生物直接芳基化的有效催化剂。芳基化的区域选择性在很大程度上取决于噻吩取代基以及芳基溴化物的性质。当使用3-甲酰基,3-氰基,3-甲基,3-羟甲基或3-溴噻吩时,以76-95%的区域选择性得到2-芳基化的噻吩。而3-甲酰基噻吩二乙基缩醛或3-乙酰基噻吩的芳基化得到5-芳基噻吩的区域选择性为52-90%。拥挤的芳基溴化物的使用有利于C5处的芳基化。这些反应仅使用0.1mol%的催化剂进行。此外,已经发现该方法耐受芳基溴化物上的各种官能团,例如甲酰基,丙酰基,苯甲酰基,腈和硝基。 催化-钯-噻吩-芳基化-CH键活化