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The α-dicarbonylmonophenylhydrazones 1 and 8 do not react as simple ,,CH-acidic compounds“ in the Mannich condensation reaction. In a concerted reaction with aminals in absolute dioxane they give rise to the products 5a-e and 10a-e with better practicability and much higher yields compared with the conventional method. The formal Mannich bases 5a/5b/5d and 10a/10b/10d with a cyclic amine part show in the dehydrogenation, using mercury- EDTA , a neighbouring group participation of the phenylhydrazono moiety yielding the corresponding lactams. With 5c only cyclization occurs leading to 1,2,4-triazine 19 in low yield, while 10c shows no dehydrogenation but an amine elimination to the vinyl-azo com pound 21 with consecutive cycloaddition leading to the 1,2-diazine 23.

α-Dicarbonylmonophenylhydrazone als Nucleophile und Nachbargruppen / α-Dicarbonylmonophenylhydrazones as Nucleophiles and Neighbouring Groups