Synthesis of 3‐aryl‐6 H ‐isoxazolo[3,4‐ d ]pyrazolo[3,4‐ b ]pyridines and 3‐aryl‐6 H ‐isoxazolo[5,4‐ d ]pyrazolo[3,4‐ b ]pyridines

The synthesis and characterization of a number of 3‐aryl‐6 H ‐isoxazolo[3,4‐ d ]pyrazolo[3,4‐ b ]pyridines and 3‐aryl‐6 H ‐isoxazolo[5,4‐ d ]pyrazolo[3,4–6]pyridines from common precursors, 5‐benzoyl‐4‐chloro‐1 H ‐pyrazolo‐[3,4‐ b ]pyridines, has been described. The structures were determined by unambiguous chemical synthesis and by isolation and 13 C nmr analysis of some key, isolated, intermediates. The ability of these compounds to displace [3 H ]flunitrazepam from CNS binding sites was also observed.