Synthesis, Alkylation and Reduction of 4-Aryl-2H-1,2,3-benzothiadiazine 1,1-dioxides

摘要

ortho-(2-Aryl-1,3-dioxolan-2-yl)benzenesulfonyl chlorides obtained from benzophenone ketals by directed ortho-lithiation chemistry were cyclized either with hydrazine monohydrate or with acetohydrazide to furnish variously substituted 4-aryl-2H-1,2,3-benzothiadiazine 1,1-dioxides. Alkylation of benzothiadiazine dioxides with alkyl iodides under basic conditions was elaborated, revealing significant differences compared to the reactivity of 4-unsubstituted ones. Hydrogenation of the C=N double bond in the presence of platinum(IV) oxide is also described. Detailed NMR studies and DFT calculations supported the structure elucidation of the compounds.