Reaction of aminals of α,β-unsaturated β-dimethylaminoaldehydes with cyclic and heterocyclic ketones and β-diketones

Conclusions

• 1. A series of δ-aminodienones was synthesized by the condensation of aminals of α,β-unsaturated β-dimethylaminoaldehydes with cyclic and heterocyclic ketones.

• 2. The dienone δ-dimethylamino-γ-methylsubstituted cyclic β-diketones are present in equilibrium with 2H-pyrans, which in organic solvents is considerably shifted in the direction of 2H-pyran, and in water in the direction of the dienone form.

• 3. In the reaction of dihydroresorcinol and dimedone with β-dimethylaminoacrolein aminal, not only δ-aminodienones but also salts of trimethinoxanines were obtained.

• 4. δ-Aminodienones obtained from acetylindoxyl and β-dimethyl amino-α-methylacrolein aminal, readily convert into 2-methyl-9-oxo-9H-pyrrolo[1.2-α]indole.