Green Synthesis of 2H-Pyrano[2,3-d][1,3]thiazole-6-carbonitriles in Trifluoroethanol as an Efficient Acidic Solvent and Their Biological Activity

A one-pot efficient, green, and environmentally friendly multicomponent synthesis of novel 2H-pyrano­[2,3-d][1,3]thiazole-6-carbonitriles has been performed in a green, low cost, mild, efficient, and commercially available 2,2,2-trifluoroethanol as solvent in the presence of a Lewis acid catalyst under ultrasonic irradiation at room temperature. The reaction was conducted with 2-chloroacetic acid, ammonium thiocyanate, aryl aldehydes, and malononitrile. This method has the advantages of high yield, clean reaction, short reaction time, simple operation, and no use of hazardous organic solvents. The synthesized compounds were charac­terized by ¹H and ¹³C NMR, IR, and mass spectra and elemental analyses and were screened for antimicrobial activities. Some of the compounds exhibited promising antibacterial and antifungal activities.