Dimethylformamide → 2-Butyl-4-chloro-5-phenylisothiazol-3(2H)-one 1,1-dioxide

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Reaction Steps

2-Butyl-4-hydroxy-5-phenylisothiazol-3(2H)-one 1,1-dioxide (444 mg, 1.58 mmol) was dissolved in dry DCM (15 mL) at rt and under an atmosphere of nitrogen. Oxalyl chloride (0.15 mL, 1.73 mmol) was added dropwise and the reaction mixture was refluxed for 1.5 h. DMF (0.08 mL) was added followed by the addition of oxalyl chloride (0.15 mL, 1.73 mmol) in 2 portions and the reaction mixture was refluxed for another 6 h. The solvents were evaporated and the residue was partitioned between water and DCM. The combined organic layers were washed with water and the two phases were separated using a phase separator. Evaporation of the organic phase gave the title compound (440 mg, 88%) as a brown oil with approximately 95% purity according to 1H-NMR and was used without further purification; 1H-NMR (400 MHz, CDCl3): δ 7.96-8.00 (m, 2H), 7.53-7.62 (m, 3H), 3.74-3.80 (t, 2H), 1.78-1.87 (m, 2H), 1.39-1-50 (m, 2H), 0.98 (t, 3H); 13C-NMR (100 MHz, CDCl3): δ 156.3, 137.1, 132.7, 129.6, 129.2, 127.6, 123.7, 40.9, 30.1, 20.1, 13.7.

Provenance & Evidence