[Br:1][C:2]1[CH:3]=[N:4][CH:5]=[C:6]([CH:10]=1)[C:7](Cl)=[O:8].Br[C:12]1[CH:18]=[CH:17][CH:16]=[CH:15][C:13]=1[NH2:14].C([O-])([O-])=O.[Cs+].[Cs+].N1C2C(=CC=C3C=2N=CC=C3)C=CC=1>[Cu]I.O1CCOCC1>[Br:1][C:2]1[CH:10]=[C:6]([C:7]2[O:8][C:12]3[CH:18]=[CH:17][CH:16]=[CH:15][C:13]=3[N:14]=2)[CH:5]=[N:4][CH:3]=1A mixture of 5-bromonicotinoyl chloride (13.46 g, 61.04 mmol), 2-bromoaniline (10.00 g, 58.13 mmol), Cs2CO3 (37.88 g, 116.3 mmol), CuI (0.554 g, 2.907 mmol), 1,10-phenanthroline (1.048 g, 5.813 mmol) and anhydrous 1,4-dioxane (110 mL) was degassed with argon for 1 h while stirring. The reaction mixture was then maintained under argon at 120° C. while stirring until TLC (SiO2, 1:1 hexanes-dichloromethane) confirmed consumption of the starting material (48 h). Upon cooling to RT, dichloromethane (ca. 200 mL) was added to the reaction, the mixture filtered, the filtrant washed copiously with dichloromethane (ca. 200 mL) and ethyl acetate (ca. 200 mL) and the filtrate concentrated in vacuo. Purification of the crude product via flash chromatography (SiO2, 100% dichloromethane to 29:1-dichloromethane:acetone) afforded 2-(5-bromopyridin-3-yl)benzo[d]oxazole (7.32 g, 46%) as a light brown crystalline solid.
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