An efficient synthesis of thiopyrano[5,6-c]coumarin/[6,5-c]chromones through intramolecular domino Knoevenagel hetero Diels–Alder reactions

The synthesis of novel polycyclic thiopyrano coumarin/chromone frameworks through intramolecular domino Knoevenagel hetero Diels–Alder reactions of 4-hydroxy coumarin and its benzo-analogous with S-prenylated aromatic aldehydes was studied. A high degree of chemoselectivity was achieved by the application of microwave irradiation and a solid support.