Unlock the C–N Bond Amidation of Enaminones: Metal-Free Synthesis of Enamides by Water-Assisted Transamidation

The C–N bond transamidation of primary amides with N,N-dimethyl enaminones has been efficiently realized by heating in the presence of trifluoromethanesulfonic acid (TfOH). The method enables the practical synthesis of valuable enamides without the use of any metal reagent. In addition, this transamidation protocol can also be expanded to the reactions of sulfonamides, and the late-stage functionalization on sulfonamide drugs such as Celecoxib and Valdecoxib has been verified. Moreover, the participation of water in assisting the transamidation process has been identified by the isotope labeling experiments using D₂O, disclosing a new possibility in designing catalytic tactic to other transamidation reactions.