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首页> 外文期刊>RSC Advances >Synthesis, characterization and evaluation of bulky bis(pyrazolyl)palladium complexes in Suzuki–Miyaura cross-coupling reactions
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Synthesis, characterization and evaluation of bulky bis(pyrazolyl)palladium complexes in Suzuki–Miyaura cross-coupling reactions

机译：铃木-Miyaura交叉偶联反应中大体积双（吡唑基）钯配合物的合成，表征和评估

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摘要

Pyrazole-containing compounds have been used in recent times as ligands to stabilize metal complexes used as pre-catalysts in cross-coupling reactions. With various substituents at various positions in the pyrazole ring, the overall electrophilic and steric properties of the metal complexes can be fine-tuned. Herein, we report the synthesis of bulky pyrazole-based ligands by condensation of methyl 4-(bromomethyl)benzoate or benzyl bromide with various substituted pyrazole compounds. These ligands were utilised in the synthesis of bis(pyrazolyl)palladium( II ) complexes. The complexes' catalytic activity in Suzuki–Miyaura cross-coupling reactions was evaluated. Phenyl bearing pre-catalyst 7 , at a catalyst loading of 0.33 mol%, successfully converted 98% of bromobenzene and phenylboronic acid to biphenyl in 4 h at 140 °C, while the tertiary butyl bearing pre-catalyst 8 converted up to 81% of the same substrates to biphenyl. An increase in conversion was seen for all pre-catalysts when an electron-withdrawing substituent was present on the aryl halide substrate, and the opposite was observed when the electron-withdrawing group was present on the phenyl boronic acid.
机译：含吡唑的化合物最近已用作配体，以稳定用作交叉偶联反应中的前催化剂的金属配合物。通过在吡唑环中的各个位置处具有各种取代基，可以对金属配合物的整体亲电子和空间特性进行微调。本文中，我们报道了4-（溴甲基）苯甲酸甲酯或苄基溴与各种取代的吡唑化合物的缩合反应，合成了庞大的吡唑基配体。这些配体用于双（吡唑基）钯（II）配合物的合成。评估了该复合物在铃木-宫浦交叉偶联反应中的催化活性。负载量为0.33 mol％的带苯基的预催化剂7在140°C的4小时内成功地将98％的溴苯和苯基硼酸转化为联苯，而带有叔丁基的预催化剂8转化率高达81％。与联苯相同的底物。当在芳基卤化物底物上存在吸电子取代基时，所有预催化剂的转化率均增加，而在苯基硼酸上存在吸电子基团时，则观察到相反的变化。

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