Efficient synthesis of novel bis(arylmethylidenes) of the 2,2-dimethyl-1,3-dithian-5-one system

摘要

In a mixture consisting of catalytic quantities of diethylamine, sodium dodecyl sulfate, and a zirconium salt in water, 2,2-dimethyl-1,3-dithian-5-one undergoes double aldol condensation with two folds of aromatic aldehydes at 50(o)C to yield the respective bisarylmethylidene derivatives efficiently within 2h. The products precipitate in the reaction mixtures spontaneously, perhaps due to high polarity of the medium, avoiding time-consuming and expensive chromatographic separations. Thus, products are isolated easily by a simple filtration and recrystallization from ethyl acetate, while the filtrate was recycled successfully for subsequent reactions.