3-Hydroxyanthranilic Acid → Methyl 2-(4-chlorophenyl)benzoxazole-4-carboxylate

Participants

Reaction Steps

2-(4-Chlorophenyl)benzoxazole-4-carboxylic acid was prepared from 3-hydroxyanthranilic acid and 4-chlorobenzoyl chloride using the method described in Step A of Example 1. This crude material (2.90 g, 10.6 mmol) was directly dissolved in DMF (40 mL), DIPEA (5.46 g, 42.4 mmol) and methyl iodide (5.93 g, 42.4 mmol) added and the reaction stirred at room temperature for 18 h. After this time the reaction was diluted with ethyl acetate (100 mL) and 2 N HCl (50 mL). The organic layer was separated and then washed with 2 N HCl (25 mL), water (50 mL) and brine (50 mL). The organic layer was then dried over sodium sulfate, filtered and concentrated to dryness to yield light yellow oil. This material was purified using silica gel chromatography to afford 0.532 g (30% yield) of methyl 2-(4-chlorophenyl)benzoxazole-4-carboxylate as a white solid: 1H NMR (300 MHz, CDCl3) δ 8.28 (dd, J=6.9, 1.8 Hz, 2H), 8.04 (d, J=8.1 Hz, 1H), 7.78 (d, J=8.1 Hz, 1H), 7.52 (d, J=8.7 Hz, 2H), 7.43 (t, J=7.8 Hz, 1H), 4.06 (s, 3H); MS (ESI) m/z 288 [M+H]+

Provenance & Evidence