Reactivity of some 3‐substituted‐6,8‐dimethylchromones toward some nucleophilic reagents

The reactivity of 3‐substituted‐6,8‐dimethylchromone derivatives 1 ‐ 5 was investigated toward selected nucleophilic reagents namely; 3‐amino‐1,2,4‐triazole, 2‐aminobenzimidazole, 7‐chloro‐4‐hydrazinoquinoline, and 5,6‐diphenyl‐3‐hydrazino‐1,2,4‐triazine. These nucleophiles were allowed to react with 6,8‐dimethylchromone‐3‐carboxaldehyde ( 1 ) through condensation with the aldehyde group with opening of γ‐pyrone ring giving compounds 6 , 7 , 10, and 11 . Reactions with 6,8‐dimethylchromone‐3‐carbonitrile ( 2 ), and 6,8‐dimethylchromone‐3‐carboxylic acid ( 3 ) occur via attack at position 2 in both compounds followed by cycloaddition onto the nitrile function (in case of carbonitrile 2 ) or decarboxylation and cyclocondensation with the carbonyl group (in case of carboxylic acid 3 ). The current nucleophilic reagents reacted with simple condensation products 4 and 5 , in boiling dioxane, through nucleophilic addition at the exocyclic vinyl bond followed by addition at the CN group giving 6,8‐dimethylchromone linked various heterocyclic systems 20 ‐ 27 .