4-Amino-2,3-dihydro-1λ⁶-isothiazole-1,1-dioxides and their chemical properties evaluation

The reactivity of the 4-amino-2,3-dihydro-1H-1λ⁶-isothiazole-1,1-dioxide (β-amino-γ-sultam) framework has not been studied sufficiently. Here we describe the chemical properties of this heterocyclic system toward electrophiles on spiranic and non-spiranic substrates. A variety of C-electrophiles (acetic anhydride, benzoyl chloride, DMFDMA, 4,4-dimethoxybutan-2-one) and heteroatom electrophiles (bromine, nitrosyl acetate) have been explored. Both the C-5 and 4-amino positions of the β-amino-γ-sultam system are able to undergo electrophilic reactions. Heteroatom electrophiles attack the C-5 position, whereas carbo-electrophiles affect the amino group. β-Amino-γ-sultams also were used as starting compounds for the synthesis of 6- or 7-substituted 1λ⁶-isothiazolo[4,5-b]pyridine-1,1-dioxides through condensation reaction and palladium-catalyzed oxidative coupling.