1.2.4- Benzothiadiazepine 1,1-dioxides, 2,5-dihydro

The 1,2,5-benzothiadiazepine 1,1-dioxide (545) and its 3,4-dihydro analogue have been prepared by the reaction of 2-nitrobenzenesulfonyl chloride with w-aminoacetophenone to give (544) followed by reductive cyclization (79JHC835). 

In MeCN, anodic oxidation of < -toluenesulfonamides yields 3-methyl-4,5-dihydro-1,2,4-benzothiadiazepine-1,1-dioxides, probably by an initial Ritter reaction followed by ring closure [138]. 

Controlled potential oxidation of o-toluenesulfonamides (180) at a platinum anode in acetonitrile using a divid cell provided 4,5-dihydro-l,2,4-benzothiadiazepine 1,1-dioxides (182) in generally good yields via (181) (Scheme 33). The scope and limitation of this one-step heterocyclization... 

Bianchi et have prepared a new class of heterocycles—the 1,2-dihydro-5//-2,l,4,5-benzothiatriazepine-2,2-dioxides (348), by diazotization and intramolecular coupling of ethyl-A (o-aminophenylsulphamoyl) acetate (347). Cycliz-ation of the corresponding acid gave a 2,1,5-benzothiadiazepin derivative (349). 

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