Sodium Carbonate → Methyl 4-(4-{[(3,5-Dimethylphenyl)sulfonyl]methyl}-5-methyl-1,3-oxazol-2-yl)benzoate

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A solution of Na2SO3 (308 mg, 2.4 mmol) and Na2CO3 (259 mg, 2.4 mmol) in water (5 mL) was added to a suspension of 3,5-dimethylbenzenesulfonyl chloride (500 mg, 2.4 mmol) in water (5 mL) and the mixture was stirred at 100° C. for 2 h. The mixture was cooled, filtered, and the filtrate was made acidic with 1 M HCl and chilled at 0° C. for 2 h. The precipitate was filtered, washed with water (1 mL) and dried. A mixture of chloride 2 (289 mg, 1.08 mmol) and crude sulfinic acid (184 mg, 1.08 mmol) in dry DMF (10 mL) was stirred at 100° C. for 16 h. The mixture was cooled and diluted with ice/water (50 mL) and stirred for 15 min. The precipitate was filtered, washed with water (5 mL). The residue purified by column chromatography, eluting with a gradient (50-100%) of EtOAc/pet. ether, to give benzoate 25 (388 mg, 90%) as a white powder: mp (EtOAc) 141-143° C.; 1H NMR (CDCl3) δ 8.03 (ddd, J=8.6, 1.8, 1.5 Hz, 2H, H-2, H-6), 7.94 (ddd, J=8.6, 1.8, 1.5 Hz, 2H, H-3, H-5), 7.42 (br s, 2H, H-2′, H-6′), 7.25 (br s, 1H, H-4′), 4.28 (s, 2H, CH2SO2), 3.94 (s, 3H, OCH3), 2.35 (s, 3H, CH3), 2.33 (s, 6H, 2×CH3); MS m/z 400.5 (MH+, 100%). Anal. calcd for C21H21NO5S: C, 63.14; H, 5.30; N, 3.51. Found: C, 63.23; H, 5.28; N, 3.46%.

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