2-Amino-4-chlorophenol → 5-Chloro-2-(3-methoxy-4-pyridin-2-ylphenyl)-1,3-benzoxazole

Participants

Reaction Steps

3-Methoxy-4-pyridin-2-yl benzoic acid (500 mg, 2.2 mmol), 2-amino-4-chlorophenol (620 mg, 4.3 mmol) and trimethyl silylpolyphosphate (2 mL) was heated to 180° C. overnight under argon. To the cooled reaction mixture, water (100 mL) was added and extracted with EtOAc (4×20 mL). Set aside organic layer. Filtered aqueous layer through Celite pad and basified filtrate to pH 9 (solid NaHCO3). Extracted with EtOAc (2×30 mL), combined all organic layers and concentrated in vacuo. The resulting orange oil was purified by flash chromatography using a gradient elution of 15:85 ethyl acetate:hexane to 1:1 ethyl acetate:hexane to give the desired intermediate, 5-chloro-2-(3-methoxy-4-pyridin-2-ylphenyl)-1,3-benzoxazole as a colorless solid.

Provenance & Evidence