Efficient activity of magnesium–aluminium hydrotalcite in the synthesis of amides

The synthesis of amides by coupling benzotriazole esters and amines can be achieved conveniently in moderate to excellent yields (50-95%) using a commercial, synthesized, calcined or reconstructed Mg-Al hydrotalcite instead of one of the classic bases (tertiary amines). The experimental results demonstrated that commercial and synthesized hydrotalcite can be quantitatively recovered from the reaction by simple filtration and reused for a number of cycles and that the reconstructed hydrotalcite is the most active form for the amide bond formation. Finally, to test the scope of the protocol for the synthesis of biologically relevant molecules, the total synthesis of Sansalvamide A was carried out.