Cu‐Catalyzed Synthesis of [1,2,3]triazolo[1,5‐c]quinazolin‐5(6H)‐one Derivatives via Sequential Reaction of Ethyl‐2‐(2‐oxoindolin‐3‐ylidene)acetate with Sodium Azide

Herein, we report a novel and efficient method for the synthesis of new class of 5‐oxo‐5,6‐dihydro‐[1,2,3]triazolo[1,5‐c]quinazoline derivatives by copper‐catalyzed reaction of α, β‐unsaturated keto/ester methyleneindolinone with sodium azide at room temperature via an azide‐alkene cyclization and ring expansion rearrangement. This method is applicable to a variety of α, β‐unsaturated keto/ester methyleneindolinone and displayed wide functional group tolerance.