Chlorosulfonic acid → 4,5-Diphenyl-4-oxazolin-2-one

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Reaction Conditions

Reaction Steps

2-Chloro-4,5-diphenyl-oxazole from Step 2 (1.53 g, 6 mmol) was added to chlorosulfonic acid cooled to 0° C. (20 mL), and the stirred solution was warmed to room temperature for 1.0 hour. The mixture was added dropwise to ice and dichloromethane (50 mL) with stirring. The resultant layers were separated, and the organic layer was washed once with water and added to a 0° C. stirred solution of ammonium hydroxide (10 mL). The mixture was stirred for 1.0 hour and extracted with dichloromethane (3×50 mL). The combined organic layers were washed with 1 N HCl followed by brine and water, dried over MgSO4 and concentrated. Recrystallization from ethyl acetate/hexanes gave a white solid (1.5 g, 75%): mp 158-159° C. 1H NMR (acetone-d6) 300 MHz δ 7.98 (d, J=8.7 Hz, 2H) 7.78 (d, J=8.7 Hz, 2H) 7.64-7.70 (m, 2H) 7.42-7.5 (m, 3H) 6.72 (bs, 2H). Anal. Calc'd. for C15H11N2O3SCl: C, 53.82; H, 3.31; N, 8.37. Found: C, 53.92; H, 3.32; N, 8.33.

Provenance & Evidence