O[C:2]1[CH:7]=[C:6]([C:8]2[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=2)[N:5]=[C:4]2[C:14]3[CH:20]=[C:19]([Br:21])[CH:18]=[CH:17][C:15]=3[O:16][C:3]=12.O=P(Cl)(Cl)[Cl:24]>>[Br:21][C:19]1[CH:18]=[CH:17][C:15]2[O:16][C:3]3[C:4](=[N:5][C:6]([C:8]4[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=4)=[CH:7][C:2]=3[Cl:24])[C:14]=2[CH:20]=14-hydroxyl-8-bromo-2-phenyl-benzofuro[3,2-b]pyridine (8.7 g, 25.72 mmol) was added to POCl3 (100 mL) The mixture was refluxed for 4 hours. TLC showed the reaction completed. POCl3 was evaporated under reduced pressure. The residue was poured into ice-water under stirring. The yellow solids precipitated out were collected by filtration to give 8-bromo-4-chloro-2-phenyl-benzofuro[3,2-b]pyridine (M6) (6.52 g, 71.01% yield).
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