The Ugi–Smiles and Passerini–Smiles Couplings: A Story About Phenols in Isocyanide‐Based Multicomponent Reactions

The Ugi–Smiles and Passerini–Smiles couplings are extensions of Ugi and Passerini reactions involving the use of acidic phenols in place of the traditional carboxylic acid partners. A Smiles rearrangement is in each case responsible for the final N‐aryl carboxamide formation. All the available data on the mechanisms and the scope of these reactions are presented. To demonstrate the interest of Ugi–Smiles and Passerini–Smiles couplings, these reactions have been further applied to the preparation of various fused heterocyclic systems. These “post‐condensation” studies are also covered in this review.