Abstract A greener and practical synthesis of 5-substituted thieno [2, 3-c] pyran-7-ones has been achieved via Cu-catalyzed coupling-cyclization of 3-iodothiophene-2-carboxylic acid with terminal alkynes in the presence of K 2 CO 3 in PEG 400 under ultrasound irradiation. A range of thienopyranone derivatives were synthesized by using this inexpensive and Pd- and ligand-free methodology.