The general procedure for the synthesis of 5-bromo-2,2'-bipyridine from 2,5-dibromopyridine and 2-(trimethylstannyl)pyridine was as follows: 1.91 g (7.89 mmol, 1.0 eq.) of 2-(trimethylstannyl)pyridine and 2.08 g (8.77 mmol, 1.1 eq.) of 2,5-dibromopyridine were dissolved in 16 mL of freshly distilled xylene. The solution was degassed and 0.061 g (0.053 mmol, 0.06 eq.) of Pd(PPh3)4 was added and stirred under reflux conditions for 15 hours. Upon completion of the reaction, 40 mL of 2N NaOH solution was added, followed by three extractions with 40 mL of toluene. The organic phases were combined, washed with brine, dried over anhydrous MgSO4 and concentrated under reduced pressure to remove the solvent. Purification by silica gel column chromatography (SiO2, 3.3 × 10 cm, pentane/EtOAc = 20:1) afforded 2.57 g (63% yield) of 5-bromo-2,2'-bipyridine as a colorless solid.
[1] Journal of Organic Chemistry, 2002, vol. 67, # 2, p. 443 - 449
[2] Synlett, 2016, vol. 27, # 7, p. 1056 - 1060
[3] Inorganica Chimica Acta, 2013, vol. 395, p. 145 - 150
[4] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 4, p. 1670 - 1673
