Eight kinds of 5-alkenyl-2,2-pentamethylene-1,3-dioxane-4,6-diones were synthesized by the Knoevenagel condensation reaction of aromatic aldehydes with 2,2-pentamethylene-1,3-dioxane-4,6-dione using CePW 12 O 40 as catalyst, without solvent under ultrasonic irradiation. The results indicate that the yields ranged from 87.6% to 94.1% when using 5% (molar fraction) CePW 12 O 40 and reacting at room temperature for 20~35 min. Furthermore, a proposed reaction mechanism for the reaction catalyzed by CePW 12 O 40 was speculated. Compared to the classical Knoevenagel condensation reaction, the main advantages of the present procedure were milder conditions, shorter reaction time and higher yields, which afforded an effective method to synthesize 5-alkenyl-isopropylidene malonate derivatines. Further study showed that CePW 12 O 40 was environmentally friendly and reused for four times without any noticeable decrease in the catalytic activity.
Six kinds of 5,5-(phenylmethylene)bis(2,2-dimethyl-1,3-dioxane-4,6-dione) derivatives were synthesized by the reaction of aromatic aldehydes and 2,2-dimethyl-1,3-dioxane-4,6-dione in biobased gluconic acid aqueous solution at 40 ℃. The reaction has the advantages of high yields (81%~92%), mild conditions, simple operation and environmental friendliness. Furthermore, GAAS can be reused for several times.
A new simple and efficient synthesis of 5,5-(phenylmethylene)bis(2,2-butylidene-1,3-dioxane-4,6-dione) derivatives, based on aromatic aldehydes and 2,2-butylidene-1,3-dioxane-4,6-dione, via Tandem reaction of Knoevenagel condensation and Michael addition is described using water as solvent without catalyst. A variety of aromatic aldehydes were engaged in study and afforded respective products in high yields (63%~83%). The reaction has the advantages of mild conditions, simple operation and environmental friendliness.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.