Treatment of all-trans-retinal with a series of l, 3-diketones using Knoevenagel conditions gave the expected condensation products. These retinylidene 1, 3-diketones were characterized and their biological activities in the hamster tracheal organ culture test measured. It was found that the cyclohexane-1, 3-dione derivatives are highly active in this in vitro assay, while other 1, 3-diketones are less active. Retinylidenedimedone has been ...
