[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH:9]=[CH:10][C:11]=1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][N:13]=1)[C:6]([OH:8])=O.[NH2:18][C:19]1[C:24](O)=[CH:23][CH:22]=[C:21]([CH3:26])[CH:20]=1.C[Si](OP(=O)=O)(C)C.C([O-])(O)=O.[Na+]>O>[CH3:1][O:2][C:3]1[CH:4]=[C:5]([C:6]2[O:8][C:24]3[CH:23]=[CH:22][C:21]([CH3:26])=[CH:20][C:19]=3[N:18]=2)[CH:9]=[CH:10][C:11]=1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][N:13]=13-Methoxy-4-pyridin-2-yl benzoic acid (490 mg, 2.1 mmol), 2-amino-p-cresol (527 mg, 4.28 mmol) and trimethylsilyl polyphosphate (2 mL) was refluxed overnight under argon. Added water (100 mL) to the cooled reaction mixture and basified to pH 8 (solid NaHCO3). Extracted with EtOAc (3×60 mL), dried (Na2SO4) and concentrated in vacuo. The resulting yellow residue was purified by flash chromatography using a gradient elution of 1:9 EtOAc:hexanes to 1:4 EtOAc:hexanes to give the desired compound, 2-(3-methoxy-4-pyridin-2-ylphenyl)-5-methyl-1,3-benzoxazole, as a yellow solid. 1H NMR (CDCl3, 300 MHz) δ 8.74 (m, 1H), 7.98–7.16 (m, 10H), 4.03 (s, 3H), 2.51 (s, 3H). (ESI) 317 (M+H)+.
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