Effect of aromatic substituents on the outcome of base-induced rearrangements of 3-acetyl-2,4-dimethyl-3,4-dihydro-2H-1,2,3-benzothiadiazine 1,1-dioxides

Abstract

In continuation of our studies on the remarkable rearrangements of 3-acetyl-7,8-dichloro-2,4-dimethyl-3,4-dihydro-2H-1,2,3-benzothiadiazine 1,1-dioxide leading to the corresponding 2,3-dihydro-1,2-benzisothiazole 1,1-dioxide or 3,4-dihydro-2H-1,2-benzothiazine 1,1-dioxide, depending on the amount of the base applied in the reaction, we have now investigated the influence of the aromatic substitution pattern on product distribution. It was found that the decreasing electron withdrawing ability of the substituents promoted the formation of enamide intermediates, potential precursors of both rearranged products. Density functional theory (DFT) has also been employed to understand the impact of the substitution pattern on product distribution.