Synthesis of benzisochalcogenol and -azole derivatives via ortho Metalation of isophthalamides

The syntheses of benzofused isochalcogenazole derivatives via ortho-lithiat ion of isophthalamides is reported. N,N'-Dialkyl-isophthalamides, C6H4-1,3- (CONHR)(2), bearing R = iPr or tBu substituents are readily ortho metalated by using 3.3 equiv, of n-BuLi/TMEDA. The organo lithium compounds react wi th S, Se, or Te to give 2-chalcogenol-isophthalamides, C6H3-1,3-(CONHR)(2)- 2-XH (X = S, Se, Te). Oxidation of the chalcogenols affords dichalcogenides under acidic and benzisochalcogenazoles under basic conditions, respective ly. The formation of the five-membered heterocycles proceeds by disproporti onation of the dichalcogenides. Oxidation of the benzisothiazoles by hydrog en peroxide gives access to substituted sulfin- and sulfonamides.