Synthesis of Benzisochalcogenol and -azole Derivatives via ortho Metalation of Isophthalamides

The syntheses of benzofused isochalcogenazole derivatives via orf/?o-lithiation of isophtha­ lamides is reported. AUV'-Dialkyl-isophthalamides, C6H4-l,3-(CONHR)2, bearing R = /Pr or fBu substituents are readily ortho metalated by using 3.3 equiv. of «-BuLi/TMEDA. The organo lithium compounds react with S, Se, or Te to give 2-chalcogenol-isophthalamides, C 6H vl,3(CONHR)2-2-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 sulfinand sulfon­ amides.