Description:
<jats:p>The syntheses of benzofused isochalcogenazole derivatives via ortho-lithiation of isophthalamides is reported. N ,N′ -Dialkyl-isophthalamides, C<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>-1,3-(CONHR)<jats:sub>2</jats:sub>, bearing R = iPr or tBu substituents are readily ortho metalated by using 3.3 equiv. of n-BuLi/TMEDA. The organo lithium compounds react with S, Se, or Te to give 2-chalcogenol-isophthalamides, C<jats:sub>6</jats:sub>H<jats:sub>3</jats:sub> -1,3- (CONHR)<jats:sub>2</jats:sub>-2-XH (X = S, Se, Te). Oxidation of the chalcogenols affords dichalcogenides under acidic and benzisochalcogenazoles under basic conditions, respectively. The formation of the five-membered heterocycles proceeds by disproportionation of the dichalcogenides. Oxidation of the benzisothiazoles by hydrogen peroxide gives access to substituted sulfin- and sulfonamides.</jats:p>