Cycloaddition von Heterocumulenen an CN-Bindungssysteme. 1. Mitteilung. Perhydro-s-triazindione und Perhydro-s-triazinyl-harnstoffe aus N,N,N′-trisubstituieten Formamidinen und Isocyanaten

The addition of methyl isocyanate to N,N-dimethyl-N′-arylformamidines 4d – 4r leads to the perhydro-s-triazine-diones 5d – 5o and to the s-triazinylureas 10a – 10k . The mechanism of formation is discussed. The addition of the arylisocyanates 18a – 18p to the N,N,N′-trialkylformamidines 9 and 27a – 27i furnishes the expected 1,4-cycloaddition products 26 and 27 in good yields. The N,N-di-isopropyl-N′-alkylformamidines 27j – 271 , however, do not undergo 1,4-dipolar cycloadditions and react with the arylisocyanate 18b to yield the alkyl isocyanates 31a – 31c and N,N-diisopropyl-N′-(p-chlorphenyl)-formamidine 32 exclusively.