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Synthesis of Diazaheterocyclic Ring‐Fused 1,2,4‐Benzothiadiazine 1,1‐Dioxides by a Sequential Aza‐Wittig/NH‐Addition Cyclization/Nucleophilic Ring‐Closure Methodology with N ‐Alkenyl‐2‐carbodiimidobenzenesulfonamides as Key Intermediates
Author(s) -
Hirota Shinsuke,
Kato Ryo,
Suzuki Madoka,
Soneta Yuji,
Otani Takashi,
Saito Takao
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200701131
Subject(s) - benzothiadiazine , chemistry , wittig reaction , ring (chemistry) , nucleophile , hydroamination , nucleophilic addition , medicinal chemistry , stereochemistry , combinatorial chemistry , organic chemistry , catalysis , intramolecular force
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)‐2 H ‐1,2,4‐benzothiadiazine 1,1‐dioxides by internal nucleophilic addition. Subsequent (tandem) cyclizations through iodoamination or hydroamination with Hg II /NaBH 4 produced a variety of diazaheterocyclic ring‐fused benzothiadiazine dioxides. In one case a methano‐bridged benzothiatriazabicyclotridecanone was obtained. The scope and limitations of these cyclizations are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)