Abstract
(1E,2Z)-2-N,N-Dialkylhydrazono-2-phenylethanal N,N-dimethylhydrazones 3a-e were
synthesised by the reaction of 1,4,5-triazapentadienium salts 2 with N,N-dimethylhydrazine. The compounds 3a and 3d did
not react with tosyl isocyanate in an electrophilic substitution
reaction at the azomethine C-1 as aza-enamines, but they reacted
at room temperature in benzene in a 1,4-dipolar cycloaddition to
yield 1,3,5-triazinan-2,4-diones 5a and 5d, whereas at 70 °C
octahydroimidazoimidazol-2,5-dione 6a was
formed via criss-cross addition reaction. With dimethyl sulfate
in DMF, 3a was transformed into the trimethylhydrazonium
salts 7a and 8a,
isolated as co-crystallised perchlorates (molar ratio 1:1).
Key words
aza-enamines - heterocycles - hydrazonium salts - 1,4-dipolar cycloaddition - criss-cross addition reaction
