A novel catalytic one-pot three-component reaction of aldehydes, o-phenylenediamine derivatives and isocyanides for synthesis of 3,4-dihydroquinoxalin-2-amine derivatives in the presence of zirconium tetrachloride

Catalyst-free synthesis of novel 1,5-benzodiazepines and 3,4-dihydroquinoxalines using isocyanide-based one-pot, three- and four-component reactions

Reaction of benzimidazolone derivatives, or their thio- or aza-counterparts, with an isocyanide in the presence of acetone unexpectedly gave rise to novel tricyclic benzodiazepine derivatives in good yield by means of a four-component reaction incorporating two moles of acetone. Benzimidazole starting substrates bearing an electron-withdrawing group gave rise instead to dihydroquinoxaline derivatives by means of a three-component reaction. Use of deuterated acetone instead of acetone in the reactions significantly affected yield and reactivity in the four-component reaction but not in the three-component reaction.

Reaction of benzimidazole derivatives with an isocyanide and acetone led to tricyclic benzodiazepine derivatives or dihydroquinoxalines depending on the nature of the substituents R¹ and R².

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.