Serendipitous Two Successive Rearrangements of Ugi Adducts Promoted by a Base and a Copper Catalyst

A unique two-step, base-promoted rearrangement of post-Ugi products under copper catalysis is presented. Mechanistic studies revealed that the rearrangement proceeds via sequential amidation, with the copper(I) catalyst facilitating the reaction through carbonyl coordination. This work not only introduces a new synthetic route for the construction of conjugated imines but also provides valuable insights into the mechanistic pathways of post-Ugi rearrangements, paving the way for further exploration of intermolecular reactions and broader synthetic applications.