Homocoupling of arylboronic acids has been successfully carried out by using the inexpensive hydrophilic palladium(
II) complex PdCl2(NH2CH2COOH)2 as catalyst in i-PrOH/H2O (v/v=1:2) under aerobic atmosphere without elevated
heating to give rise to symmetrical biaryls in moderate to good yields. The aqueous media, room temperature reaction
and the low amounts of catalyst (0.5 mol%) show a practical and environmentally benign protocol. In addition, enhancement
of yield was observed in the presence of 0.5 equiv. p-toluenesulfonyl chloride. Furthermore, the byproducts of
this reaction were not observed while biaryl is the only product, which results in much more facile in the separation of the
product symmetrical biaryls from arylboronic acids.
使用廉价的亲
水性
钯(II)络合物PdCl2(NH2CH2COOH)2作为催化剂,在
异丙醇/
水(体积比1:2)的溶剂中,无需升高温度,在有氧条件下,成功实现了芳基
硼酸的自偶联反应,得到了中等至良好产率的对称
联苯。该反应采用
水相介质、室温条件以及低量的催化剂(0.5 mol%),展现了一种实用且环境友好的方法。此外,在存在0.5当量的
对甲苯磺酰氯时,产率得到了提升。更为重要的是,该反应仅生成
联苯,无其他副产物,使得从芳基
硼酸中分离出对称
联苯产品变得极为简便。