Chlorination of 2H-1,2,3-benzothiadiazine 1,1-dioxide(1) in wet methylene chloride gives o-formylbenzenesulfonyl chloride (4), but in dry methylene chloride at 0° yields the chlorosultine 3-chloro-3H-2,1-benzoxathiole 1-oxide (2); the latter is readily hydrolyzed to the "pseudo-acid" 3H-2,1-benzoxathiol-3-ol 1-oxide (3) which on further chlorination forms 4. In 1,2-dichloroethane at −20° chlorination of 1 gave the "coupled product" 14, whereas in dimethylformamide at room temperature the cyclic acyl chloride hydrazone 4-chloro-2H-1,2,3-benzothiadiazine was isolated in poor yield. The acyl chloride hydrazones (16) were the products obtained following chlorination of some representative aromatic acyclic tosylhydrazones (15). 3H-2,3,4-Benzothiadiazepine2,2-dioxide (19), a previously unknown heterocyclic system, was synthesized in two steps from 1,3-dihydrobenzo[c]thiophene (17). Chlorinolysis of 19 gave o-chloromethylbenzal chloride (21). These reactions are believed to involve formation of the α-chloroazo compound (e.g. 22) as the first step. The formation of 2 from 1 is discussed in terms of three possible routes, two which involve the sulfene 23.

2H-1,2,3-Benzothiadiazine 1,1-dioxide (6) and 2,l-benzoxathiin-3-one 1,1-dioxide (5), representatives of little-known heterocyclic systems, have been synthesized from sodium o-formylbenzenesulfonate (7). Thermolysis of 5 and 6 was investigated in the hope of finding evidence for the formation of a sulfene. No characterized product was obtained from 5, but 6 gave the sultine 3H-2,1-benzoxathiole 1-oxide (21), the compound expected from the sulfene 20.

Die Chlorierung des Benzothiadiazin‐S,S‐dioxids (I) in wasserfreiem Methylen‐ Chlorid bei 0°C führt zum Chlorsultin (IIa), das in wäßrigem Medium sofort zur "Pseudosäure" (IIb)hydro1ysiert wird.

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Durch Reaktion des Benzolsulfonats (I) mit Thionylchlorid in Gegenwart von DMF zum Sulfonylchlorid (II) (das Isomere (III) entsteht als Nebenprodukt) und Umsetzung von (II) mit Hydrazinhydrat wird das Benzothiadiazindioxid (IV) synthetisiert; durch Reaktion des nach Literaturangaben aus (I) erhältlichen Sultons (V) über die Stufen (VI) und (VII) wird das Benzoxathiinondioxid (VIII) dargestellt.