Studies on the Chemical Transformations of 6-Methylchromone-3-carbonitrile under Nucleophilic Conditions

The chemical reactivity of 6-methylchromone-3-carbonitrile (1) was studied towards some nucleophilic reagents. Reaction of carbonitrile 1 with malononitrile dimer and N'-[(4-methoxyphenyl)methylidene]-2-cyanoacetohydrazide (5) gave the unexpected chromeno[4,3-b]pyridine 2 and benzoxocine-3-carbohydrazide 6, respectively. Reaction of carbonitrile 1 with 3-amino-1,2,4-triazole, 2-aminobenzimidazole, 7-chloro-4-hydrazinoquinoline and 3-hydrazino-5,6-diphenyl-1,2,4-triazine proceeds via gamma-pyrone ring opening followed by cycloaddition onto the nitrile function leading to a variety of heterocyclic systems. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.