Synthesis of new heterocyclic systems—substituted spiro[chromene-4,3′-indoles] and spiro[indole-3,4′-quinolines]

Advances in the Synthesis of Benzo‐Fused Spiro Nitrogen Heterocycles: New Approaches and Modification of Old Strategies

“…When 2‐(2‐oxoindol‐3‐ylidene)malononitriles or ethyl 2‐(2‐oxoindol‐3‐ylidene)cyanoacetate derivatives were used as α‐cyanoethylene component in the Michael reactions with 1,3‐dicarbonyl compounds 32 or acetylacetone on prolonged heating in boiling ethanol in the presence of a catalytic amount of tris (2‐hydroxyethyl)amine, the same fused 4 H ‐pyran derivatives 34 and 35 [122] were also obtained ( Scheme 10 ,c ). Similar synthesis of compound 34 (R 1 =R 3 =Me, R 2 =H, R 4 =CO 2 Me) was also described [123] . There are publications of the results of non‐catalytic synthesis analogs of heterocycle 34 from isatins, cyclic α‐methylenedicarbonyl compounds and malononitrile in an aqueous medium under microwave irradiation [124] …”

“…Multicomponent reactions of isatins with malononitrile or ethyl ester of cyanoacetic acid are quite often also used in the preparation of indolone‐pyran spiro‐fused heterocycles [116–126] . The electrocatalytic multicomponent synthesis of nanoparticles of spirooxindole 31 was carried out using an electrogenerated base of the propanol anion in a one‐pot, three component condensations of isatins 22 , dimedone 32a , and malononitrile in an undivided cell in the presence of sodium bromide as an electrolyte at 50 °C.…”

Synthesis, characterization, and application of CoFe2O4@amino‐2‐naphthol‐4‐sulfonic acid as a novel and reusable catalyst for the synthesis of spirochromene derivatives

“…Synthesis of new spiro heterocycles has been widely reported such as spiro[chromene-4,3 0indoles], spiro[indole-3,4 0 -quinolines], and spiropyranopyrazoles. [29][30][31] Among various spiro heterocycles, chromene-containing spirooxindoles have attracted significant attention because of their remarkable biological properties including antianaphylactic, anticancer, anticoagulant, diuretic, and spasmolitic activities. These compounds usually were synthesized through a three-component reaction of acenaphthoquinone or isatin with cyanoacetic ester or malononitrile and 1,3-dicarbonyl compounds.…”