Highly selective synthesis of 4(5)-aryl-, 2,4(5)-diaryl-, and 4,5-diaryl-1H-imidazoles via Pd-catalyzed direct C-5 arylation of 1-benzyl-1H-imidazole
作者:Fabio Bellina、Silvia Cauteruccio、Annarita Di Fiore、Chiara Marchetti、Renzo Rossi
DOI:10.1016/j.tet.2008.01.051
日期:2008.6
direct C-2 arylation of imidazoles 9 with aryl halides under base-free and ligandless conditions. On the other hand, the four-step synthesis of imidazoles 1 from 8 also involves the regioselective bromination of compounds 9 and a Suzuki reaction of the resulting 5-aryl-1-benzyl-4-bromo-1H-imidazoles 11 with arylboronic acids 5 under phase-transfer conditions, followed by N-debenzylation.
为4(5)的制备高度选择性的,实用,高效的协议-芳基- 1 H ^ -咪唑2,2,4(5)-diaryl-1 ħ -咪唑3,和4,5-二芳基-1- ħ -描述了咪唑1。这些协议的关键步骤是通过Pd催化商用C 1-苄基1 H-咪唑(8)与芳基卤化物的直接C-5芳基化反应,选择性合成5-芳基-1-苄基1 H-咪唑9-区域选择性。。由8的化合物3的三步合成还涉及咪唑的Pd催化和Cu介导的直接C-2芳基化反应9在无碱和无配体条件下与芳基卤化物反应。另一方面,由8的四步合成咪唑1还涉及化合物9的区域选择性溴化和所得的5-芳基-1-苄基-4-溴-1 H-咪唑11与芳基硼酸的Suzuki反应。在相转移条件下为5,然后进行N-脱苄基作用。