Uma variedade de sistemas heterocíclicos contendo o sistema 1-etilquinolin-2(1H)-ona, foi preparada a partir da reação de 3-(nitroacetil)-1-etil-4-hidroxiquinolin-2(1H)-ona com alguns reagentes eletrofílicos e nucleofílicos. Além da sua ciclização para 5-etil-2-(hidroxiimino)-2,3,4,5-tetrahydrofuro[3,2-c]quinolina-3,4-diona, o composto 3-(nitroacetil)-1-etil-4-hidroxiquinolina-2(1H)-ona foi bromado, clorado, formilado, acetilado, e condensado com cromona-3-carbonitrila e 2-amino-3-formilcromona. Alguns novos pirazolo [4,3-c]

2-Methylchromones, although scarce in nature, constitute a group of oxygen heterocyclic compounds which have shown significant biological activities. Their transformations into other biologically active compounds have been exploited. This review describes the work on the synthesis and reactions of 2-methylchromones as well as their biological evaluation.

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The chemical reactivity of 3‐nitrochromone (1) was studied towards some nucleophilic reagents. Reaction of 3‐nitrochromone (1) with some carbon nucleophiles revealed existence of ring‐opening ring‐closure reactions, and the mode of cyclization depends on the nucleophile used. Treatment of 3‐nitrochromone (1) with malononitrile and ethyl cyanoacetate produced benzoxocinone derivatives 2 and 3, respectively. Boiling compound 1 with cyanoacetamide and 2‐aminoprop‐1‐ene‐1,1,3‐tricarbonitrile afforded pyridine derivatives 4 and 5, respectively. Reaction of compound 1 with 1H‐benzimidazol‐2‐ylacetonitrile, 5‐amino‐2,4‐dihydro‐3H‐pyrazol‐3‐one, and dimedone led to pyrido[1,2‐a]benzimidazole 6, pyrazolo[3,4‐b]pyridine 7, and chromenone 8, respectively. Treating 3‐nitrochromone (1) with heterocyclic amines gave enaminones 11 and 12 via nucleophilic attack at C‐2 position with ring opening. The structures of the newly synthesized products were deduced on the basis of their analytical and spectral data.