Isothiazole Constructionby Metal-Free Reactions ofThioamides with Iminoiodinanes and Their Photophysical Properties

Metal-free reactions of thioacetamide derivatives with <i>N</i>-sulfonyliminoiodinane, affording isothiazoles under mild conditions, are described. 2-Substituted thioacetamides modified with an enamine moiety undergo reactions with iminoiodinane to form 4,5-disubstituted isothiazoles in 72–93% yields. Reactions of (het)arylidene-substituted 2-thioacetamides and iminoiodinane with subsequent one-pot oxidation of the formed sulfonylisothiazolines afford 3,4,5-trisubstituted isothiazoles in 44–96% yields. A scale-up synthesis of the developed methods was performed. The photophysical properties of the new isothiazoles were investigated, and UV- or blue-light-shifted fluorescence has been detected (QY up to 11%).