Abstract
3-Dimethylamino-2,2-dimethyl-2H-azirine (1) and 4-phenyl-3,4-dihydro-2H-1,2,4-benzothiadiazin-3-on-1,1-dioxide react already below room temperature to give a nine-membered heterocyclic product, namely 3-dimethylamino-4,4-dimethyl-7-phenyl-4,5,6,7-tetrahydro-1,2,5,7-benzothiatriazonin-6-on-1,1-dioxide (7, Scheme 2) in a quantitative yield. The structure of this new heterocycle has been confirmed by X-ray crystallographic analysis (Fig. 1 and 2). In Scheme 2 a reaction mechanism for the formation of 1 is discussed, the zwitterion b being the key intermediate.
Schläpfer-Dähler, Marlise