2-Bromothiophene → 4-Bromo-5-methyl-[2,2']bithienyl

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A solution of 2-bromothiophene (1.44 g, 8.8 mmol) in anhydrous Et2O (25 mL) was treated with magnesium turnings (0.257 g, 10.6 mmol) and heated at reflux for 45 min under a nitrogen atmosphere. The heat source was removed and the reaction mixture was allowed to cool to room temperature when it was added to a cooled (0° C.) solution of 3,5-dibromo-2-methylthiophene (2.0 g, 8.8 mmol), Pd(dppf)Cl2 (13 mg, 0.018 mmol) and anhydrous Et2O (10 mL) dropwise via a canula. The reaction was stirred at this temperature for 1 h, the cooling bath was removed, the mixture was allowed to slowly come to room temperature and stirred for 16 h when it was quenched with 5% HCl (10 mL). The aqueous layer was separated and extracted with Et2O (2×20 mL). All organic extracts were combined, washed with H2O (3×20 mL), followed by brine (20 mL), dried (Na2SO4) and filtered. The solvent was evaporated under reduced pressure and the crude product was purified using column chromatography through silica gel (hexanes) yielding 1.69 g of pure product as a white solid.

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