The 2,1-benzisothiazolo[2,3-b]-2,1-benzisothiazole system,synthesis and properties

2,2′-Diaminodiphenylmethane and its 4,4′-dibromo-derivative both react with N-sulfinylmethanesulfon-amide to form 2,1-benzisothiazole derivatives. Methylation or acetylation of these provides examples of the hypervalent sulfur 2,1-benzisothiazolo2,3-b]-2,1-benzisothiazole system. The nmr spectra of these compounds are discussed.