Synthesis of 2,5,7‐Triaryl‐4,7(6,7)‐dihydropyrazolo[1,5‐ a ]pyrimidine‐3‐carbonitriles by Reaction of 5(3)‐Amino‐3(5)‐aryl‐1 H ‐pyrazole‐4‐carbonitriles with Chalcones

The reaction of 5(3)‐amino‐3(5)‐aryl‐1 H ‐pyrazole‐4‐carbonitriles with 1,3‐diaryl‐2‐propen‐1‐ones (chalcones) in refluxing DMF leads to 2,5,7‐triaryl‐4,7(6,7)‐dihydropyrazolo[1,5‐ a ]pyrimidine‐3‐carbonitriles. In DMSO solution, the latter exist in equilibrium of two tautomeric 4,7‐dihydropyrazolo[1,5‐ a ]pyrimidines and 6,7‐dihydropyrazolo[1,5‐ a ]pyrimidines in various ratios, depending on the nature of aryl substituents in chalcone building blocks.