Brønsted Acid‐Catalyzed Three‐Component 1,3‐Dipolar Cycloadditions of 1,2‐Disubstituted Alkynes with Aldehyde‐Generated Azomethine Ylides

The first 1,3‐dipolar cycloadditions (1,3‐DCs) of 1,2‐disubstituted alkynes with aldehyde‐generated azomethine ylides have been established, leading to the efficient synthesis of poly‐substituted 2,5‐dihydropyrroles.The Brønsted acid‐catalyzed three‐component 1,3‐DCs of but‐2‐ynedioates, aldehydes, and diethyl 2‐aminomalonate tolerate a wide range of substrates, offering structurally diverse poly‐substituted 2,5‐dihydropyrroles in high yields. This protocol not only provides an easy and efficient approach to poly‐substituted 2,5‐dihydropyrroles but also greatly enriches the chemistry of 1,3‐DCs, especially alkyne‐involved 1,3‐DCs.