Diazonium Salts Induced Divergent Synthesis of α,β‐Unsaturated‐Azo‐Substituted‐Quinazolin‐2(1 <i>H</i> )‐ones and Quinolinones via Sequential Cyclization and Skeletal Rearrangement

Abstract We have successfully developed a novel synthetic route for the synthesis of α,β‐unsaturated‐azo‐substituted‐quinazolin‐2(1 H )‐one via a reaction between 1,3‐diphenylurea analogues and diazonium salts, facilitated by a diazonium salt‐induced intramolecular cyclization process. Notably, this reaction exhibits remarkable tolerance toward a wide range of substituents, resulting in the formation of diverse products under mild reaction conditions. Additionally, we discovered that rearrangement occurs under alkaline conditions, leading to the formation of α,β‐unsaturated‐azo‐substituted‐quinolinone derivatives.