Diethyl N,N ‐dimethylaminomethylenemalonate in the synthesis of fused heterocyclic systems

The reactions of diethyl N,N ‐dimethylaminomethylenemalonate ( 3 ) with N‐ and C ‐ nucleophiles were studied. In the reaction of 3 with heterocyclic amines 4 , with the amino group attached at α‐position in respect to the ring nitrogen atom, substitution of the dimethylamino group in 3 with the heterocyclic amino took place to give diethyl heteroarylaminomethylenemalonates 5 , which can cyclize into fused azino‐ 6 or azolopyrimidinones 7 . In the reaction of 3 with the compound with an active methylene group attached at α‐position in regard to the ring nitrogen atom, such as pyridinylacetonitrile ( 8 ), ethyl pyridinyl‐ ( 9 ), and quinolinylacetate ( 10 ), fused quinolizines 11 and 12 , and benzo[ c ]quinolizine 13 were formed, respectively. Heterocyclic systems with an active or potentially active methylene group incorporated in the ring system, such as pyrazole 14 , pyrimidine 15 , and pyridine derivative 18 , gave with 3 fused pyranones 16, 17 , and 19 , and dihydroxynaphthalenes 22 and 23 naphtho[2,1‐ b ]pyranones 24 and 25 .