Piperidine‐Promoted Three‐Component Condensation: Synthesis of Chromene Heterocycles and Pyrazolotriazoles

Chromenes, the oxygen‐containing heterocyclic compounds, have a “special” place in biologically active natural products and in synthetic chemistry and in the fields of medicinal, agrochemical, cosmetic, and pigment industries. In this work, piperidine was used as a base catalyst for the convenient synthesis of 1,4‐dihydropyrano[2,3‐c]pyrazole, 5,10‐dihydro‐4H‐benzo[g]chromene, and pyrazolo[1,2‐a] [1,2,4]triazole derivatives at ambient temperature. This methodology has several advantages including the use of easily accessible and inexpensive catalysts, short reaction times, high yields, convenient work‐up, and not needing column chromatography. Piperidine was applied as a base catalyst for the convenient synthesis of 1,4‐dihydropyrano[2,3‐c]pyrazole, 5,10‐dihydro‐4H‐benzo[g]chromene, and pyrazolo[1,2‐a] [1,2,4]triazole derivatives at ambient temperature. This methodology has several advantages including the use of easily accessible and inexpensive catalysts, short reaction times, high yields, convenient work‐up, and not needing column chromatography.