Reactions of 3-bromo-2,3-dihydro- and 2,3-dibromo-4H-1-benzothiopyran-4-one 1,1-dioxides with various amines

Abstract

Reactions of 2,3-dibromo-4H-1-benzothiopyran-4-one 1,1-dioxide (1) and 3-bromo-2,3-dihydro-4H-1-benzothiopyran-4-one 1,1-dioxide (4) with various amines have been studied. Novel 2-alkylamino and arylamino derivatives (2a–g) were obtained from the reactions of (1) with alkylamines and primary aromatic amines, respectively. The reaction of (1) with secondary aromatic amines gave 2-aryl derivatives (3) together with 2-arylamino derivatives. Tertiary aromatic amines under the same conditions gave only 2-aryl derivatives (3d–i). The reactions of (4) with aromatic amines gave directly the 3-substituted thiochromone 1-oxides (5a–c), which were oxidized with hydrogen peroxide to the corresponding sulphones (6a–c). The ring-closure product (8) was obtained from the reaction of (4) with o-aminobenzenethiol.