Synthesis of diazaheterocyclic ring-fused 1,2,4-benzothiadiazine 1,1-dioxides by a sequential aza-Wittig/NH-addition cyclizationucleophilic ring-closure methodology with N-alkenyl-2-carbodiimidobenzenesulfonamides as key intermediates

摘要

Treatment of N-alkenyl-2-azidobenzenesulfonamides with triphenylphosphane and subsequent subjection of the resulting iminophosphoranes to aza-Wittig reactions with isocyanates generated functionalized carbodiimides, which spontaneously underwent cyclization to form 2-alkenyl-3(R-2-substituted amino)-2H-1,2,4-benzothiadiazine 1,1-dioxides by internal nucleophilic addition. Subsequent (tandem) cyclizations through iodoamination or hydroamination with Hg-II/NaBH4 produced a variety of diazaheterocyclic ringfused benzothiadiazine dioxides. In one case a methano-bridged benzothiatriazabicyclotridecanone was obtained. The scope and limitations of these cyclizations are reported. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451. Weinheim, Germany, 2008).