Cycloadditionen von Heterocumulenen an CN‐Bindungssysteme. 2. Mitteilung. Perhydro‐ s ‐triazindione und cyclische Aminimide aus N,N‐Dimethyl‐N′‐dimethylamino‐formamidin und Isocyanaten

The addition of the arylisocyanates 12a–12p to N,N‐dimethyl‐N′‐dimethylaminoformamidine ( 7 ) leads to the cyclic aminimides 14a–14p . Methyl isocyanate and phenyl isotiocyanate react with 7 in an analogous manner and yield the compounds 24 resp. 30 . The arylisocyanates 12q–12v , however, which contain electron‐withdrawing groups in the ortho ‐ and/or meta ‐position, undergo 1,4‐dipolar cycloadditions and react with the amidine 7 to furnish the perhydro‐ s ‐triazine‐diones 22a–22ff . The mechanism of these reactions is discussed.