Recyclable task-specific acidic ionic liquid [NMP]H2PO4: Microwave-assisted, efficient one-pot, two-step tandem synthesis of fused thiazolo[2,3-b]quinazolinone and thiazolo[2,3-b]quinazoline derivatives

A novel, time-effective, eco-conscious and microwave-assisted tandem one-pot, two-step reaction has been described for the synthesis of thiazolo[2,3-b]quinazolinone (4a-f) and thiazolo[2,3-b]quinazoline (5a-t) derivatives in quantitative yield in the presence of inexpensive, acidic task-specific ionic liquid [NMP]H2PO4. All the synthesized compounds were well established by comparison with their literature values (H-1 NMR, melting points, mass spectrometry and elemental analysis). The remarkable advantages of this methodology over existing conventional heating, such as increasing yields, decreasing reaction times, formation of products in an analytically pure form, operational simplicity, less energy consumption, cost-effectiveness, recyclability and reusability of the catalyst, make this protocol "green" and environmentally benign. [GRAPHICS] .