Substrate scope for tetrahydro-8H-pyrazolo[4,3-f]pyrimido[4,5-b]quinoline-8,10(9H)-dione 5(a–k)^a,b,c.

^aUnless specified otherwise, all the reactions were performed using 1 (1 mmol), 2a (1 mmol), 3(a–k) (2 mmol), and DEM (20 mol%) in 5 mL of ethanol stirred at 70 °C for stipulated time.

^bYield of the product 5.

^cReaction time.