Br[C:2]1[CH:7]=[CH:6][C:5]([Br:8])=[CH:4][N:3]=1.[Br:9][C:10]1[CH:11]=[C:12](B(O)O)[CH:13]=[CH:14][CH:15]=1.C([O-])([O-])=O.[Na+].[Na+].CCO>[Pd].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(C)C=CC=CC=1>[Br:8][C:5]1[CH:6]=[CH:7][C:2]([C:14]2[CH:13]=[CH:12][CH:11]=[C:10]([Br:9])[CH:15]=2)=[N:3][CH:4]=1A mixture of 2,5-dibromopyridine (4.33 g, 17.7 mmol), 3-bromophenylboronic acid (4.70 g, 21.3 mmol), tetrakis(triphenylphosphine) palladium (0) (800 mg, 0.692 mmol), 2 M Na2CO3(aq) (18 cm3), EtOH (18 cm3) and toluene (50 cm3) was degassed and heated at reflux with a bath temperature of 105° C. under argon for 23 h. The reaction was allowed to cool and the two phases were separated. The aqueous layer was extracted with ether (3×15 cm3). The organic layer and the ether extracts were combined, washed with brine (1×40 cm3) and dried over anhydrous sodium sulfate. The solvents were completely removed to leave an orange oil. The oil was purified by column chromatography over silica gel using DCM-light petroleum (0:1 to 1:10) as eluent to give 2.50 g (45%) of B-1 as a pale yellow solid; δH (200 MHz; CDCl3) 7.26-7.42 (1 H, m, ArH), 7.57 (2 H, m, PyH & ArH), 7.88 (2 H, m, PyH & ArH), 8.14 (1 H, m, ArH), and 8.74 (1 H, m, PyH); m/z [CI(NH3)] 312, 314, 316 (MH+).
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