Indium(III)-catalyzed knoevenagel condensation of aldehydes and activated methylenes using acetic anhydride as a promoter

Article abstract of DOI:10.1021/acs.joc.5b00011

The combination of a catalytic amount of InCl₃ and acetic anhydride remarkably promotes the Knoevenagel condensation of a variety of aldehydes and activated methylene compounds. This catalytic system accommodates aromatic aldehydes containing a variety of electron-donating and -withdrawing groups, heteroaromatic aldehydes, conjugate aldehydes, and aliphatic aldehydes. Central to successfully driving the condensation series is the formation of a geminal diacetate intermediate, which was generated in situ from an aldehyde and an acid anhydride with the assistance of an indium catalyst.