Substrate selective synthesis of pyrazolo[1,5-a]pyridines through [3 + 2] cycloaddition of N-aminopyridines and β-nitro styrenes

Synthesis of 2 or 3-(hetero)aryl pyrazolo[1,5-a]pyridines through [3 + 2] cycloaddition ofN-aminopyridine with β-nitrostyrenes followed byin situdenitration under metal-free and mild conditions are described.