Synthesis and Reactions of (1E,2Z)-2-N,N-Dialkylhydrazono-2-phenylethanal N,N-Dimethylhydrazones

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

References

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  Brehme, R.; Gründemann, E.; Schneider, M.; Radeglia R.; Reck, G.; Schulz, B. Synthesis 2003, in print.

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