Ugi-Smiles and Passerini-Smiles Couplings

This chapter proposes a more comprehensive review including all data available on Ugi reactions as well as the various transformations performed on the adducts, mainly derived by Ugi-Smiles, to demonstrate the synthetic utility of these couplings. As very few research groups have yet explored these reactions, the authors mostly present results from their own group and also emphasize relevant experimental details for implementation of Ugi-Smiles-based strategies. The chapter presents a discussion on various carboxylic acid surrogates for Ugi reactions as well as the general principles controlling Smiles rearrangements to provide the necessary background for the readers. The Ugi-Smiles couplings and Passerini-Smiles couplings of phenols and mercaptan offer new four-component access to N-aryl and O-aryl derivatives. Since the Passerini-Smiles coupling offers less diversity, most efforts were devoted to Ugi-Smiles adducts, focusing on transformations involving the newly introduced aryl moieties in order to move away from traditional Ugi postcondensations.