Sequential Organocatalytic Synthesis of Triazoloquinolines

In this work, a one‐pot sequential organocatalytic method for the synthesis of fused [1,2,3]triazolo[1,5‐a]quinolines through successive cyclization and condensation is presented. In this synthetic strategy, the intermolecular [3+2]‐cycloaddition occurs between 1,3‐dicarbonyl compounds and o‐carbonyl‐substituted phenylazide compounds, for the formation of the 1,2,3‐triazole intermediates. Subsequently, an intramolecular condensation reaction generates the fused quinoline ring by the new C−C bond formation, giving the products in yields ranging from moderate to excellent. All the reactions were performed using 20 mol% of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as catalyst in the presence of DMSO as solvent at 120 °C for 24 h and tolerate a range of 1,3‐dicarbonyl compounds, such as β‐keto esters and 1,3‐diketones, and o‐formyl, o‐acetyl or o‐benzoyl substituted phenylazide compounds.