Studies on Isothiazoles. III. A Novel Ring Closure to Isothiazoles by the Reaction of α-Amino Ketones with Thionyl Chloride or Sulfur Monochloride

Abstract
New compounds, 4-hydroxyisothiazoles, have been prepared by the reaction of α-amino ketones with thionyl chloride or sulfur monochloride, which is a novel procedure for cyclization to an isothiazole ring. Polar solvents, especially dimethylformamide (DMF), were preferable for this cyclization. The reaction hardly proceeded in a nonpolar solvent such as benzene, but was accelerated by an addition of a small amount of DMF.