alpha-dicarbonylmonophenylhydrazones as nucleophiles and neighbouring groups

The alpha -dicarbonylmonophenylhydrazones 1 and 8 do not react as simple,,C H-acidic compounds" in the Mannich condensation reaction, In a concerted re action 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 t he 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 e limination to the vinyl-ate compound 21 with consecutive cycloaddition lead ing to the 1,2-diazine 23.