Hydrochloric Acid → 2-Butyl-5-(4-chlorophenyl)-4-hydroxyisothiazol-3(2H)-one 1,1-dioxide

Participants

Reaction Conditions

Reaction Steps

The reaction was done in two vials. In each vial: N-butyl-1-(4-chlorophenyl)methanesulfonamide (0.5 g, 1.91 mmol) was dissolved in THF (3 mL). Ethyl oxalate (0.335 g, 2.29 mmol) was added. The mixture was cooled in an ice-bath. Potassium tert-butoxide (0.28 g, 2.48 mmol)) was added under nitrogen atmosphere. The mixture was heated in a microwave reactor at 150° C. for 10 mins. It was then cooled in an ice-bath. HCl (10%, ca.1 mL) was added, pH˜1. The mixtures of the two vials were combined and evaporated to remove THF. It was then extracted with DCM (20 mL). The extract was dried (MgSO4) and evaporated. Column chromatography (ISOLUTE SI, 20 g/70 mL) of the residue, eluting with heptane, then EtOAc:heptane (20:80), gave fraction A (0.9 g, containing ca. 60% of the title compound) and fraction B (0.035 g, the title compound). 1H NMR (400 MHz, THF-d8): δ 7.92 (d, 2H), 7.50 (d, 2H), 3.68 (t, 2H), 1.82-1.76 (m, 2H), 1.49-1.39 (m, 2H), 0.97 (t, 3H). 13C NMR (100 MHz, THF-d8): 159.2, 146.7, 135.4, 129.8, 129.4, 125.6, 117.7, 39.8, 31.2, 20.6, 13.7. Mass Spectrum: M−H+ 314.

Provenance & Evidence