A straightforward method for the synthesis of 2-bromo-4-alkylthiophenes was developed, and the desired products were obtained in the highest chemical yields (>90%) reported to date. 2-Bromo-4-alkylthiophenes were synthesized by regioselective lithiating of 3-alkylthiophenes with n-BuLi and quenching with bromine at −78 °C. Moreover, a simple and efficient protocol for the synthesis of dihexyl-2,2′-bithiophenes was developed by employing 2-bromo-4-hexylthiophene instead of the commonly used monomer, 2-bromo-3-hexylthiophene. Kumada and Suzuki cross-coupling reactions were conducted to synthesize the desired products as head-to-tail (HT) and tail-to-tail (TT) regioisomers in high yields and excellent selectivity.

中文翻译：

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选择性和直接合成的2-溴-4-烷基噻吩：合成头到尾（HT）和尾到尾（TT）二己基-2,2'-联噻吩的简便明了的方法

开发了一种简单的合成2-溴-4-烷基噻吩的方法，并以迄今报道的最高化学收率（> 90％）获得了所需的产物。通过用正丁基锂对3-烷基噻吩进行区域选择性锂化并在-78°C下用溴淬灭来合成2-Bromo-4-烷基噻吩。此外，通过使用2-溴-4-己基噻吩代替常用的单体2-溴-3-己基噻吩，开发了一种简单而有效的合成二己基-2,2'-联噻吩的方案。进行了Kumada和Suzuki交叉偶联反应，以高收率和优异的选择性合成了所需的产物，如头对尾（HT）和尾对尾（TT）区域异构体。