An efficient in-situ reduction and cyclization reaction for the synthesis of 9-aryl-1,6,8,9-tetrahydro-7H-pyrazolo[3,4-f]quinolin-7-one, 11-aryl-1,6,7,8,9,11-hexahydro-10H-pyrazolo [3,4-a]acridin-10-one, and 11-aryl-3,6,7,8,9,11-hexahydro-10H-imidazo[4,5-a]acridin-10-one derivatives

Abstract

An efficient in-situ reduction and cyclization reaction was reported from the aromatic aldehydes, 6-nitro-1H-indazole (5-nitrobenzimidazole), and 2,2-dimethyl-1,3-dioxane-4,6-dione (1,3-cyclohexanedione or dimedone) to synthesize 9-aryl-1,6,8,9-tetrahydro-7H-pyrazolo[3,4-f]quinolin-7-one, 11-aryl-1,6,7,8,9,11-hexahydro-10H-pyrazolo [3,4-a]acridin-10-one, and 11-aryl-3,6,7,8,9,11-hexahydro-10H-imidazo[4,5-a]acridin-10-one derivatives in the presence of SnCl2·2H2O in THF medium. The advantages of this method are mild conditions, convenient manipulation, high yields and wide range of substrates.