Regioselective Suzuki Cross-Coupling Reactions at the 2-Position of Di- and Tribrominated Pyrroles
作者:Thorsten Bach、Sven Schröter
DOI:10.1055/s-2005-871939
日期:——
The 2,3,4-tribromopyrrole 4 and the 2,3-dibromopyrrole 10 were shown to undergo regioselective Suzuki cross-coupling reactions at the 2-position. After optimization best yields in the reaction with 4-tert-butylphenyl boronic acid (5a) were 68% and 86%. Other boronic acids 5 were employed in the reaction with pyrrole 4 and gave the monosubstitution products 6 in 33-52% yield. A subsequent cross-coupling at positions C-3 and C-4 could be achieved on 3,4-dibromopyrrole 6a (84% yield).
研究表明,2,3,4-三溴吡咯 4 和 2,3-二溴吡咯 10 可在 2 位发生区域选择性铃木交叉偶联反应。经过优化后,与 4-叔丁基苯硼酸(5a)反应的最佳产率分别为 68% 和 86%。其他硼酸 5 与吡咯 4 反应的单取代产物 6 的收率为 33-52%。随后,3,4-二溴吡咯 6a 在 C-3 和 C-4 位置发生了交叉耦合(收率为 84%)。