Silica Sulphuric Acid Catalyzed Intra‐molecular Alkyne Carbonyl Metathesis (ACM): A Rapid Access to 2H‐ Chromenes

A highly efficient, convenient and ecofriendly approach to access highly functionalized 2H ‐chromenes via intramolecular aldehyde alkyne metathesis reaction was established starting from readily accessible alkyne‐tethered 2‐((3‐phenylprop‐2‐yn‐1‐yl) oxy)benzaldehydes and catalyzed by silica sulfuric acid (SiO 2 ‐OSO 3 H, SSA) coupled with microwave irradiation. This reaction was well tolerated for various substituents including different functional groups and furnished the desired highly functionalized 2 H ‐chromene derivatives in good to excellent yields in a very short time. A systematic study of the conventional heating approach and microwave irradiation was performed to demonstrate the advantages of the microwave‐assisted condition in terms of high yield and shorter reaction time.