An amphoteric mesoporous silica catalyzed aldol reaction

A bi-functional mesoporous silica material, containing both carboxylic acid and amino groups, acts as a catalyst for the reaction between aldehydes and carbon nucleophiles. We demonstrate reaction conditions under which even aldehydes containing deactivating electron donating groups, or sterically demanding substituents, undergo the catalyzed reaction with acetone, affording primarily the condensation products. Moreover, we demonstrate that acetophenone and ethyl methyl ketone can replace acetone as nucleophile. The bi-functional mesoporous silica is a convenient catalyst, as it is simple to remove from the reaction media, thereby facilitating workup.