Highly selective base-catalyzed ring closing Ugi-adducts from the reaction of 2-formylindole, 2-bromoacetic acid, amines and isocyanides

An efficient and practical approach for the synthesis of indoloquinolines and indolo/pyrroloquinoxalines via a Cu-catalyzed Ugi-C/Ugi-N-arylation sequence

A Cu-catalyzed tandem transformation of Ugi adducts through CH/NH bond functionalization reactions was reported for synthesizing a broad spectrum of indolo/pyrrolo-[1,2-a]quinoxaline-6/4-carboxamide, 7H-indolo[2,3-c]quinoline-6-carboxamide, and 1-(cyclohexylamino)-14H-indolo[2,3-c][1,4]oxazino[4,3-a]quinolin-4(3H)-one derivatives in moderate to excellent yields. In this protocol the Ugi condensation of aromatic aldehydes, anilines, acids, and isocyanides leads to the formation of bis-amides in methanol at room temperature. This approach employed simple reaction conditions, including Ugi product as starting material, CuI, l-proline as a ligand, and cesium carbonate, in DMSO for 8 h. This method demonstrated efficiency in synthesizing fused-nitrogen-containing heterocycles through a convenient pathway.

Highly regioselective and diastereoselective synthesis of novel pyrazinoindolones via a base-mediated Ugi-N-alkylation sequence

An efficient base-mediated/metal-free approach has been developed for the synthesis of 1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide derivatives via intramolecular indole N-H alkylation of novel bis-amide Ugi-adducts. In this protocol the Ugi reaction of (E)-cinnamaldehyde derivatives, 2-chloroaniline, indole-2-carboxylic acid and different isocyanides was designed for the preparation of bis-amides. The main highlight of this study is the practical and highly regioselective preparation of new polycyclic functionalized pyrazino derivatives. This system is facilitated by Na₂CO₃ mediation in DMSO and 100 °C conditions.

The status of isocyanide-based multi-component reactions in Iran (2010-2018)

Isocyanides as key intermediates and magic reactants have been widely applied in organic reactions for direct access to a broad spectrum of remarkable organic compounds. Although the history of these magical compounds dates back more than 100 years, it still has been drawing widespread attention of chemists who confirmed their versatility and effectiveness. Because of their wide spectrum of pharmacological, industrial and synthetic applications, many reactions with the utilization of isocyanides are reported in the literature. In this context, Iranian scientist played a significant role in the growth of isocyanides chemistry. The present review article covers literature from the period starting from 2010 onward and encompasses new synthetic routes and organic transformation involving isocyanides by Iranian researchers. During this period, a diverse range of isocyanide-based multi-component reactions (I-MCRs) has been reported such as a new modification of Ugi, post-Ugi, Passerini and Groebke-Blackburn-Bienayme condensation reactions, isocyanide-based [1 + 4] cycloaddition reactions, isocyanide-acetylene-based MCRs, isocyanide and Meldrum's acid-based MCRs, several unexpected reactions besides green mediums and novel catalytic systems for the synthesis of diverse kinds of pharmaceutically and industrially remarkable heterocyclic and linear organic compounds. This review also emphasizes the neoteric applications of I-MCR for the synthesis of valuable peptide and pseudopeptide scaffolds, enzyme immobilization and functionalization of materials with tailorable properties that can play important roles in the plethora of applications.

Isocyanide-based multicomponent reactions in the synthesis of heterocycles

In this review, we update our previous presentation, underscoring the recent applications of isocyanides as privileged synthons in the synthesis of various heterocyclic compounds, especially focused on those synthesizedviamulticomponent reactions.