A selective and direct synthesis of 2-bromo-4-alkylthiophenes: Convenient and straightforward approaches for the synthesis of head-to-tail (HT) and tail-to-tail (TT) dihexyl-2,2′-bithiophenes

✍ Scribed by Ashraf A. El-Shehawy; Nabiha I. Abdo; Ahmed A. El-Barbary; Jae-Suk Lee

• Publisher: Elsevier Science
• Year: 2010
• Tongue: French
• Weight: 406 KB
• Volume: 51
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2010.06.100

✦ Synopsis

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 À78 °C. Moreover, a simple and efficient protocol for the synthesis of dihexyl-2,2 0 -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.