Synthesis of Certain 3‐Aminopyrazolo[5,4‐ b ]pyridine and 3,4‐Substituted Pyrido[2′,3′ :3,4]pyrazolo[5,1‐ c ][1,2,4]triazine Derivatives

2‐Thioxo‐1,2‐dihydropyridine derivatives 2a , 2b were reacted with methyl iodide to give 2‐methylthiopyridines 3a , 3b , which were reacted with hydrazine hydrate to produce 3‐aminopyrazolo[5,4‐ b ]pyridines 4a , 4b . Compounds 4a , 4b were diazotized to afford the corresponding diazonium salts 5a , 5b , which were reacted with some active methylene compounds 6a – 6h to give the corresponding pyrido[2′,3′:3,4]pyrazole[5,1‐ c ][1,2,4]triazines 7 – 14 .