Var i ous types of bi o log i cal ac tiv ity have been es tab- lished for pyra zoles and pyrazolopyridines.1-9 In view of the in ter est in these com pounds and in con tin ua tion of our syn - the sis of azoloazines,10-16 we re port herein the util ity of 3-amino-5-chloro-1-phenylpyrazole -4-carboxaldehyde (1) for the syn the sis of sev eral new pyrazolo[3,4-b]pyridine de - riv a tives re quired for a me dic i nal chem is try. 3-Amino-5-chloro-l-phenylpyrazole-4- ...