1, 3‐Dimethylbarbituric Acid Promoted Metal‐Free Cascade Annulation for Straightforward Access to Benzimidazole‐Fused Heterocycles. Issue 23 (14th June 2022) - Alizadeh, Abdolali
Abstract: A convenient and novel 1, 3‐dimethylbarbituric acid‐mediated methodology for constructing diverse benzimidazole‐fused heteroaromatics has been developed. This metal‐free cascade annulation of readily available 3‐formylchromones, 1, 2‐diaminoarenes, and cyclic 1, 3‐dicarbonyl compounds provides an alternative synthetic route in the green conditions. 1, 3‐Dimethylbarbituric acid acts as a protecting group and accelerates intramolecular cyclization. This one‐pot protocol proceeds through cascade nucleophilic addition, ring‐opening, Michael‐type addition, intramolecular cyclization, elimination, and air oxidation reactions. Abstract : A convenient and novel 1, 3‐dimethylbarbituric acid‐mediated methodology for constructing diverse benzimidazole‐fused heteroaromatics has been developed. This metal‐free cascade annulation of readily available 3‐formylchromones, 1, 2‐diaminoarenes, and cyclic 1, 3‐dicarbonyl compounds provides an alternative synthetic route in the green conditions. 1, 3‐Dimethylbarbituric acid acts as a protecting group and accelerates intramolecular cyclization. This one‐pot protocol proceeds through cascade nucleophilic addition, ring‐opening, Michael‐type addition, intramolecular cyclization, elimination, and air oxidation reactions.