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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 |
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| Authors: | Ashraf A El-Shehawy Nabiha I Abdo Ahmed A El-Barbary |
| Institution: | a Department of Nanobio Materials and Electronics, School of Materials Science and Engineering, and Research Institute for Solar & Sustainable Energies (RISE), Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea b Department of Chemistry, Faculty of Science, Kafr El-Sheikh University, Kafr El-Sheikh 33516, Egypt c Department of Chemistry, Faculty of Science, Tanta University, Tanta 31527, Egypt |
| Abstract: | 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. |
| Keywords: | Alkylthiophenes Bromination Grignard reagents 2 2&prime -Bithophenes Dihexylbithiophenes HH- and TT-cross-couplings Kumada and Suzuki cross-couplings |
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