An easy one-step synthesis of imidazolin-2-ones from phthalic anhydrides and their antioxidant evaluation

Treatment of phthalic anhydride derivatives with trimethylsilyl azide affords benzimidazolin-2-ones in 45–91% yield, which is the result of two consecutive Curtius reactions. Within the series obtained, 1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one showed highest antioxidant activity.