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Endo-1,3-Dipolar cycloaddition of azomethine ylides generated in situ from 11H-indeno[1,2-b]quinoxalin-11-one and L-proline/thiaproline to (E)-1,5-diarylpent-4-ene-1,3-diones led to the 3-hydroxy-3-aryl-1-(1′-arylspiro[indeno[1,2-b]quinoxaline-11,3′-(thia)pyrrolizidin]-2′-yl)prop-2-en-1-ones containing the 1,3-diketone fragment. Upon processing of these adducts with arylhydrazine hydrochlorides in an acidic medium, the 2′-(1,3-diaryl-1H-pyrazol-5-yl)-1′-arylspiro[indeno[1,2-b]quinoxaline-11,3′-pyrrolizidines] were formed as individual regioisomers. In a similar reaction with hydrazine hydrate and hydroxylamine, the corresponding hybrids bearing the N-unsubstituted pyrazole and isoxazole moieties were obtained. Most of spiro[indenoquinoxaline-pyrrolizidine]-N-arylpyrazole conjugates have shown high cytotoxic activity against the HeLa cancer cell line.

A one-pot three-component reaction of azomethine ylides generated in situ from isatins and sarcosine with 3-nitro-2-(trifluoromethyl)-2H-chromenes in i-PrOH at 55–60 °C leads to the kinetically controlled products – exo-spiro[chromeno[3,4-c]pyrrolidine-3,3′-oxindoles]. When this reaction is carried out in 1,4-dioxane under reflux, the thermodynamically controlled endo-spiro[chromeno[3,4-c]pyrrolidine-1,3′-oxindoles] are preferably formed. The isomerization of the kinetic products in DMSO solution at different temperatures has been studied by NMR spectroscopy and the stepwise mechanism of reversible [3+2] cycloaddition has been confirmed. The cytotoxic activity of some CF3-substituted spiro[chromeno[3,4-c]pyrrolidine-oxindoles] against the HeLa cell line was evaluated by the MTT test.