A general and practical preparation of alkylidene Meldrum’s acids

Although many methods have been reported for the Knoevenagel condensation of aldehydes and Meldrum’s acid, most are not general or use unconventional reagents and conditions. We have found that alkylidene Meldrum’s acids form readily in benzene solution under mild pyrrolidinium acetate catalysis, and that this reaction is general, highly functional group compatible, and can be scaled-up easily.